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PG&E’s Emerging Technologies Program ET Project ET13PGE1311

Emerging Technologies (ET) Lidded

Thermostatic Infrared Broiler Field Study

Food Service Technology Demo Kitchen

ET Project Number: ET13PGE1311

Project Manager: Jeff Beresini Charlene Spoor Pacific Gas and Electric Company Prepared By: David Zabrowski Adam Cornelius Denis Livchak Edward Ruan

Fisher-Nickel, Inc. 12949 Alcosta Blvd., Suite 101 San Ramon, CA 94583

Issued: December 15, 2014

Copyright, 2014, Pacific Gas and Electric Company. All rights reserved.

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ACKNOWLEDGEMENTS

Pacific Gas and Electric Company’s Emerging Technologies Program is responsible for this project. It was developed as part of Pacific Gas and Electric Company’s Emerging Technology – Energy Efficient Commercial Food Service Equipment Demo and Showcase program under internal project number 2500960993. Fisher-Nickel, Inc (FNI) conducted this technology evaluation for Pacific Gas and Electric Company (PG&E) with overall guidance and management from Jeff Beresini and Charlene Spoor. For more information on this project, contact [email protected] or [email protected].

Special thanks to the contributors to this report: David Cowen, Mark Finck, Janel Rupp,

LEGAL NOTICE

This report was prepared for PG&E for use by its employees and agents. Neither PG&E nor any of its employees and agents:

(1) makes any written or oral warranty, expressed or implied, including, but not limited to those concerning merchantability or fitness for a particular purpose;

(2) assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, process, method, or policy contained herein; or

(3) represents that its use would not infringe any privately owned rights, including, but not limited to, patents, trademarks, or copyrights.

DISCLAIMER

In no event will FNI be liable for any special, incidental, consequential, indirect, or similar damages,

including but not limited to lost profits, lost market share, lost savings, lost data, increased cost of

production, or any other damages arising out of the use of the data or the interpretation of the data

presented in this report.

FNI is neutral as to fuel and energy sources. Fisher-Nickel, Inc. does not endorse particular products or

services from any specific manufacturer or service provider. FNI is strongly committed to evaluating the

performance of foodservice equipment using the best available scientific techniques and instrumentation.

FNI test results are made available to the general public through technical research reports and

publications and are protected under U.S. and international copyright laws. Reproduction or distribution of

the whole or any part of the contents of this document without reference to PG&E and FNI is prohibited.

This report was prepared as a result of work sponsored by the California Public Utilities Commission

(CPUC). It does not necessarily represent the views of the CPUC, its employees, or the State of

California. The CPUC, the State of California, its employees, contractors, and subcontractors make no

warranty, express or implied, and assume no legal liability for the information in this report; nor does any

party represent that the use of this information will not infringe upon privately owned rights. This report

has not been approved or disapproved by the CPUC nor has the CPUC passed upon the accuracy or

adequacy of the information in this report.

mailto:[email protected]

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ABBREVIATIONS AND ACRONYMS

ASTM American Society for Testing and Materials

Btu British Thermal Unit

DCKV Demand-Controlled Kitchen Ventilation

ET Emerging Technologies

F Fahrenheit

FNI Fisher-Nickel, Inc.

FSTC Food Service Technology Center

ft Foot

h Hour

HVAC Heating, Ventilating and Air Conditioning

IR Infrared

lb Pound

kW Kilowatt

kWh Kilowatt-hour

PG&E Pacific Gas and Electric Company

PIER Public Interest Energy Research

RD&D Research, Development, and Design

scf Standard Cubic Foot

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CONTENTS

EXECUTIVE SUMMARY ................................................................................................1

INTRODUCTION .........................................................................................................3

Emerging Technologies Project Background ........................................................ 3

Benefits to California ....................................................................................... 5

Project Assessment Objectives / Goals ............................................................... 5

Methodology ................................................................................................... 6

Technology / Product Evaluation Approach ......................................................... 7

Description of Existing Technologies ......................................................... 7 Description of New Technologies ............................................................ 10

FIELD ANALYSIS, RESULTS, AND RECOMMENDATIONS ....................................................14

Norm’s Place (Danville, CA) ............................................................................ 14

Technical Approach ............................................................................... 14 Baseline Results ................................................................................... 14 Replacements Results ........................................................................... 17 Customer Feedback/Recommendations ................................................... 20

The Growler (Danville, CA) ............................................................................. 20

Technical Approach ............................................................................... 20 Baseline Results ................................................................................... 21 Replacements Results ........................................................................... 24 Customer Feedback/Recommendations ................................................... 29

Sideboard (Danville, CA) ................................................................................ 29

Technical Approach ............................................................................... 29 Baseline Results ................................................................................... 29 Replacement Results ............................................................................. 32 Customer Feedback/Recommendations ................................................... 37

Esin (Danville, CA) ........................................................................................ 37

Technical Approach ............................................................................... 37 Baseline Results ................................................................................... 38 Replacement Results ............................................................................. 40 Customer Feedback/ Recommendations .................................................. 48

LIDDED BROILER SHOWCASE ......................................................................................49

CUSTOMER FEEDBACK SURVEY ..................................................................................50

Purchasing Influences .................................................................................... 50

Site Operating Practices ................................................................................. 50

Lidded Char-broiler Feedback .......................................................................... 50

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APPENDIX 1: APPLIANCE SPECIFICATIONS ....................................................................1

APPENDIX 2: SURVEY RESULTS .....................................................................................2

Esin Pre-monitoring Survey .............................................................................. 2

Esin Post-monitoring Survey ............................................................................. 4

Growler Pre-monitoring Survey ......................................................................... 7

Growler Post-monitoring Survey ........................................................................ 9

Sideboard Pre-monitoring Survey .................................................................... 12

Sideboard Post-monitoring Survey .................................................................. 14

APPENDIX 3: “CASE STUDIES IN ENERGY-EFFICIENT LIDDED CHAR-BROILERS” SHOWCASE

(10/20/14) .........................................................................................................17

REFERENCES ...........................................................................................................21

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TABLES

Table ES-1. Linear Feet of Broilers, Energy Use, and Potential

Energy Use by IOU ....................................................... 5

Table 1. Lidded Underfired Broiler Lab Testing Results .................... 10

Table 2. Three-foot Underfired Broiler Energy Performance Testing

Results ..................................................................... 12

Table 3. Growler’s Existing Broiler Specifications ............................ 22

Table 4. Sideboard’s Existing Broiler Specifications ......................... 30

Table 5. Esin’s Existing Broiler Specifications ................................. 39

Table 6. Restaurant Name, Location, and Upgraded Broiler .............. 52

FIGURES

Figure 1. Field Monitoring Gas Meter Connected to a Data Logger in

the Lab (Left) and in the Field (Right) ............................. 4

Figure 2. Field Monitoring Gas Meter Connected to a Data Logger in

the Lab (Left) and in the Field (Right) ............................. 7

Figure 3. Underfired Broiler Heater Source ...................................... 8

Figure 4. Temperature Uniformity Plot for Three-foot Wide

Standard Underfired Broiler ........................................... 9

Figure 5. Lidded Underfired Broiler ............................................... 12

Figure 6. Norm's Place Exterior (Left) and Interior Bar and Dining

Area (Right) .............................................................. 14

Figure 7. Existing Broiler at Norm's Place ...................................... 15

Figure 8. Thursday Feb. 28, Typical Energy Profile of Existing

Broiler at Norm’s Place ................................................ 15

Figure 9. Existing Broiler Energy Use and Hours of Operation at

Norm’s Place ............................................................. 16

Figure 10. Replacement Broiler at Norm’s Place ............................. 17

Figure 11. Thursday September 19, Typical Energy Profile of

Replacement Broiler at Norm’s Place ............................. 17

Figure 12. Replacement Broiler Energy Use and Hours of Operation

at Norm's Place .......................................................... 18

Figure 13. Energy Profile Comparison: Existing to Replacement

Broiler at Norm’s Place ................................................ 19

Figure 14. Daily Energy Regression Comparison at Norm’s Place:

Existing to Replacement Broiler .................................... 20

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Figure 15. Existing Broiler Carried Over from the Previous Owners

to The Growler ........................................................... 21

Figure 16. Existing Broiler Input Knob Settings at The Growler ......... 22

Figure 17. Wednesday May 7, Typical Energy Profile of Existing

Broiler at The Growler ................................................. 23


The Growler............................................................... 23

Figure 19. Replacement Broiler Installed on Cook Line at The

Growler ..................................................................... 24

Figure 20. Thursday June 19, Typical Energy Profile of Replacement

Broiler at The Growler ................................................. 24

Figure 21. Replacement Thermostatically-Controlled Broiler

Thermostat Setpoint at The Growler ............................. 25


at The Growler ........................................................... 26


Infrared Burners at The Growler ................................... 26

Figure 24. Energy Use Comparison at The Growler: Pre- to Post-

Behavioral Change at The Growler ................................ 27

Figure 25. Energy Profile Comparison at The Growler: Existing to

Replacement Broiler (After Behavioral Changes) ............ 28

Figure 26. Daily Energy Regression Comparison at The Growler:

Existing to Replacement Broiler (After Behavioral

Changes) .................................................................. 28

Figure 27. Existing Broiler at Sideboard ........................................ 30

Figure 28. Wednesday May 7, Typical Energy Profile of Existing

Broiler at Sideboard .................................................... 31


Sideboard ................................................................. 32

Figure 30. Replacement Lidded, Thermostatically-Controlled Broiler

Installed on Sideboard Cook Line ................................. 32

Figure 31. Lidded Broiler Thermostat at Sideboard Set for 400°F...... 33

Figure 32. Wednesday June 14, Typical Energy Profile of

Replacement Broiler at Sideboard ................................. 33


at Sideboard .............................................................. 34


Thermostat Setpoint at Sideboard ................................ 35

Figure 35. Energy Use Comparison: Pre- to Post-Behavioral Change

at Sideboard .............................................................. 35

Figure 36. Energy Profile Comparison: Existing to Replacement

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Broiler (After Behavioral Changes) ............................... 36

Figure 37. Daily Energy Regression Comparison: Existing to

Replacement Broiler (After Behavioral Changes) ............ 36

Figure 38. Esin Exterior (Left) and Interior Bar (Right) .................... 37

Figure 39. Existing Broiler at Esin ................................................. 38

Figure 40. Wednesday July 30, Typical Energy Profile of Existing

Broiler at Esin ............................................................ 39


Esin .......................................................................... 40

Figure 42. Replacement Lidded, Thermostatically-Controlled Broiler

Installed on Cook Line at Esin ..................................... 40

Figure 43. Monday September 1, Typical Energy Profile of

Replacement Broiler at Esin ......................................... 41


at Esin ...................................................................... 42


Infrared Burners at Esin .............................................. 42

Figure 46. Energy Profile Comparison at Esin: Existing to

Replacement Broiler ................................................... 43

Figure 47. Daily Energy Regression Comparison at Esin: Existing to

Replacement Broiler ................................................... 44

Figure 48. DCKV Optical Sensor Inside Esin’s Hood ......................... 45

Figure 49. Esin’s Exhaust Fan Power Consumption .......................... 46

Figure 50. Esin’s DCKV System Settings ........................................ 46

Figure 51. Average Daily Fan Energy Profile at Esin ........................ 47

Figure 52. Lidded Broiler Demonstration at the 10/20/2014

Showcase at FSTC ...................................................... 49

Figure 52. Daily Energy Use Before and After Broiler Replacement ... 53

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EXECUTIVE SUMMARY

The underfired broiler is a common medium- to heavy-duty piece of commercial foodservice

equipment. In establishments where broilers are used to cook meat, seafood and grilled

vegetables, they function as one of the central kitchen appliances. The signature charred

taste, aroma and appearance of food cooked on a broiler cannot be achieved through other

cooking processes.

A commercial underfired broiler is one of the most energy-intensive appliances in the

kitchen. When not being actively used, broilers are typically kept in a ready-to-cook idle

state, so they operate at close to their peak energy input rate regardless of whether or not

they are cooking. As a result, the annual costs of operating an underfired broiler can often

exceed the purchase price of the equipment. Their high operating temperatures place a

tremendous load on kitchen HVAC systems, requiring high exhaust flow rates and

introducing a significant amount of heat into the surrounding kitchen space. Broiler designs

have changed little over the last 30 years; with new technological advances, there are now

new opportunities to change these designs to provide significant energy savings.

PROJECT GOAL

The goal of this study was to determine performance gains and gas energy savings when

using advanced equipment incorporating improved designs and controls. The objectives of

the study were to characterize inefficiencies of standard underfired broiler technologies

through field data collection, to compare the energy use of standard and energy-efficient

lidded thermostatically-controlled broiler technologies under both idle and cooking

conditions in the laboratory, and to examine differences in restaurant broiler energy use

between a standard and lidded broiler at several different field monitoring locations. The

study also sought to determine any additional reductions in energy use as a result of the

behavioral changes of operators, and to identify potential ventilation savings associated with

Demand-Controlled Kitchen Ventilation (DCKV) integration.

PROJECT DESCRIPTION

Four sites were selected for assessment, monitoring, and evaluation, ranging from fine

dining to casual dining. The existing broiler’s daily energy use and hours of operation were

monitored for a minimum of two weeks. After baseline data had been collected and

analyzed, the existing broiler was replaced with broilers of the same size that utilized

thermostatic controls, infrared (IR) burners, and a heat retention lid. Data on the

replacement broilers was collected for a period of at least two weeks and the data compiled

and analyzed. At two of the four restaurants, more detailed instruction and training was

provided to staff and management on the replacement broilers. The effects of these

behavioral changes on broiler operation were then collected for an additional period of at

least two weeks and the findings compiled and analyzed.

PROJECT FINDINGS/RESULTS

Overall, there is great potential for savings with the lidded, infrared, thermostatically-

controlled broiler—especially in restaurants that leave their units idling for long periods.

Replacing the standard broiler with a thermostatically-controlled, lidded, IR broiler resulted

in an average 30% energy savings, or an average of about two and a half therms daily. An

additional 32% energy savings was realized at the two sites where training was

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implemented to foster behavioral changes. By utilizing the lid wherever possible,

appreciable energy savings were achieved at all four restaurant locations. If the lid was not

closed, the lidded broiler operated like a standard, non-thermostatically-controlled broiler

and no any sizable energy savings were realized. Operators noted improved cooking

performance due to the relative temperature uniformity of the lidded broiler’s IR burners.

The study also demonstrated the significance of proper training. As exhibited by the data

taken from one of the sites that implemented broiler best-practices, training to optimize

lidded broiler operations could more than double the savings realized by switching to a more

efficient broiler without significantly impacting normal restaurant operation.

RECOMMENDATIONS

The savings realized by lidded broilers makes it a viable early-replacement candidate. With

cost savings between $750 and $1,000 at the sites studied, owners could realize a four year

or less simple payback period based on the broiler’s current $3,800 purchase price. A rebate

equivalent to the first year of savings could reduce this payback period to under three

years—further enhancing the potential for its increased adoption in the marketplace. For full

market adoption, however, the lidded broiler concept will need to be refined and promoted

more by manufacturers. The price for lidded broilers has significant room to drop once per-

unit manufacturing costs begin to decrease (a result of rising demand and the associated

increases in both economies of scale) and as manufacturer competition increases.

While these studies may have illustrated the benefits of switching to lidded,

thermostatically-controlled IR broilers, they have also highlighted targeted areas for

improvement. The current lidded broiler design causes the smoke plume to shift slightly

forward, which may hamper ventilation. Restaurants with ventilation hoods that barely

capture and contain the plume of a standard broiler under heavy load conditions will most

likely see cooking effluent spillage when cooking heavy loads with the open lidded broiler.

Manufacturers could explore several avenues for potential energy-saving design

enhancements to the lidded broiler—Including automatic pilot ignition systems, split broiler

lids, better lid insulation, and the use of demand-response ventilation systems. A two-stage

gas valve controlled by lid position may be an alternative to the thermostat. With the merits

of this emerging technology now validated, further investigation should be made into

quantifying the benefits of its specific features. For example, studies could be done on

unlidded broilers with IR burners, or on lidded broilers with conventional atmospheric

burners rather than IR burners. Isolating and investigating the different features of the

advanced broiler type used in this study could provide more insight on the contribution of its

individual features towards energy savings. Through this type of investigation, broiler

technology could be further refined for combined energy and cost-effectiveness.

In terms of behavioral changes, investigating new cooking techniques involving closed-lid

cooking should also prove to be valuable. Education and training of kitchen staff on best

operational practices, combined with the aforementioned design changes, would maximize

the potential energy savings of lidded, thermostatically-controlled IR broilers in restaurants.

California foodservice operators stand to significantly benefit from the adoption of this

technology. Reducing the notoriously high gas use of the underfired broiler by enhancing

the design with these new features will improve productivity, lower utility bills, and reduce

broiler energy use and the carbon emissions associated with additional gas consumption.

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INTRODUCTION

EMERGING TECHNOLOGIES PROJECT BACKGROUND PG&E’s ET program was created to fund field placement studies of energy-efficient

equipment in California. The primary objective of the ET program is to promote the

California Energy Wise rebate program by highlighting the performance of rebate-qualified

equipment in real-world operating situations. The FSTC’s role in this program involves

replacing low- or standard-efficiency existing equipment in targeted foodservice

establishments based on a site assessment; design consultation; measuring pre- and post-

replacement energy use and calculating savings; and following up with a demo showcase

event to share the project’s successes and lessons learned.

The project utilized recent findings in a PIER study completed by Fisher-Nickel, Inc. (FNI)

that characterized the inventory, energy load, and energy-efficiency potential of various

primary cooking appliances found in commercial and institutional foodservice sectors in the

state of California. The goal of the PIER study was to identify energy-efficient needs in the

restaurant industry; identify equipment with the highest energy loads; and outline specific

strategies to stimulate Research, Development, and Design (RD&D) improvements in

energy efficiency and productivity to support regulatory and utility-based incentive

programs around this equipment. This ET program augments the PIER study by

demonstrating “proof-of-concept” in live kitchens for implementing these energy reduction

strategies to support current and future utility-based incentives for more efficient

equipment. It will also help increase awareness in the foodservice industry of the real-world

performance of energy-efficient equipment, further driving manufacturer research and

development as demand for this type of equipment continues to grow.

This particular project focused on underfired broiler technology. The conventional underfired

broiler’s design has not changed much in the past 30 years. Broilers have an input rating of

about 15,000 Btu/h per burner and as much as 500-2,500 Btu/h for the standing pilot

alone. The energy-efficiency range for a conventional underfired broiler is 20%-30%,

relatively low in comparison with other commercial kitchen appliances. Standard underfired

broilers also are not thermostatically-controlled, display poor heating uniformity across the

cooking surface, and pose a challenge to ventilation systems due to their intense thermal

plumes. Figure 1 below provides a Schlieren image of a conventional char-broiler’s thermal

plume under a hood.

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Photo Credit: FNI

FIGURE 1. FIELD MONITORING GAS METER CONNECTED TO A DATA LOGGER IN THE LAB (LEFT) AND IN THE FIELD (RIGHT)

To mitigate the above mentioned shortcomings, manufacturers modified a standard broiler

design to create a production unit with infrared (IR) burners, thermostatic controls, and a

lid element. These additional features increase broiler heat retention and lower energy input

require for normal restaurant operation. This advanced broiler has the potential to decrease

cooking time, energy use and heat pollution to the kitchen, while also improving cooking

uniformity. The FSTC has tested broilers in the lab that were equipped with infrared (IR)

burners. Results of these laboratory tests showed cooking-energy efficiency gains between

37% and 53% over standard broilers equipped with atmospheric burners. Heat distribution

is also much improved with the use of IR burners. This study examines and quantifies the

benefits available by replacing conventional underfired broiler technology with lidded IR

thermostatically broiler technology.

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BENEFITS TO CALIFORNIA In a 2010 PIER study, the FSTC estimated that roughly 126,000 linear feet of underfired

broilers were in operation in California commercial kitchens (Mills, Zabrowski 2010). In that

report, the annual natural gas use of underfired broilers in California was estimated to be

70.9 million therms, assuming that a standard underfired broiler operated at approximately

30% efficiency. The average daily energy use of standard broilers measured in the four

restaurants featured in this study, combined with the three additional restaurants analyzed

in the 2013 PIER study, was determined to be 8.58 therms. Of these seven restaurants, five

would be considered good candidates for replacement with a lidded broiler, since the

standard broiler was being used more than eight hours a day and the kitchen ventilation

system had adequate capability. The three-foot standard-efficiency broilers in these five

restaurants had an average daily energy use of 9.17 therms, or 3.06 therms per linear foot.

Approximately 40% of broilers are in PG&E territory. Replacing 25% of units in this territory

alone, or approximately 12,600 linear feet of broiler, to advanced lidded broilers would

generate approximately 30% energy savings. Thirty percent savings from replacing 12,600

linear feet of standard-efficiency broilers averaging 3.06 therms per day and operating 364

days per year could result in an annual savings of 4.2 million therms in PG&E territory

alone. Table ES-1 shows the estimated number of linear feet of broiler, gas use, and

potential savings across the three investor-owned utilities (IOUs) in California:

TABLE ES-1. LINEAR FEET OF BROILERS, ENERGY USE, AND POTENTIAL ENERGY USE BY IOU

IOU: LINEAR FEET OF

BROILERS (FT) STANDARD BROILER ENERGY

USE (MMTHERMS) POTENTIAL ENERGY SAVINGS

BY CA IOU (MMTHERMS)

Southern California Gas

63,000 35.5 5.3

Pacific Gas & Electric Co.

50,400 28.4 4.2

San Diego Gas & Electric

12,600 7.1 1.1

TOTAL 126,000 70.9 10.5

Source: FNI

PROJECT ASSESSMENT OBJECTIVES / GOALS The objective of the study was to validate the energy savings and improved production

performance associated with a lidded infrared broiler through comparative field testing.

The goals of the commercial gas underfired broiler study were to:

Characterize the energy consumption of standard underfired broiler technologies

through field data collection at several different field monitoring locations.

Compare standard and energy-efficient lidded thermostatically-controlled broilers in

energy use in both idle and cooking laboratory conditions.

Examine restaurant broiler energy use with a standard and lidded broiler at several

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different field monitoring locations.

Determine any additional reductions in energy use as a result of behavioral changes

of operators.

Determine potential ventilation savings associated with Demand-Controlled Kitchen

Ventilation (DCKV) integration.

Provide recommendations that will continue to advance underfired broiler efficiency

and transform the market for this appliance category.

METHODOLOGY Four restaurants were selected for standard broiler monitoring. After the existing broiler’s

daily energy use and hours of operation were metered, the broilers were replaced with

lidded thermostatically-controlled broilers of the same size. Energy monitoring was

conducted on the replacement broilers for a minimum of two weeks. Broiler usage patterns

and restaurant operation remained the same with the replacement broiler and the pre-

existing standard broiler.

Once data was analyzed for the initial monitoring period, FSTC staff returned to two of the

four restaurants to promote behavioral changes in support of proper lidded broiled

operation. Broiler training included the following items:

• Reiterating to the cooks and the manager to close the lid when the broiler was empty

(show energy savings vs. potential energy savings).

• Explaining that closing the lid will make the kitchen “cooler”.

• Warning about the potential burn hazards of grabbing the lid handle improperly, and

showing the best points to use the lid handle.

• Showing operators where to locate thermostat on the broiler, and describing to them

how it works; explaining the benefits of reducing the thermostat to a temperature

between 350°F and 450°F

• Demonstrating how to modulate the burner input knobs when cooking with the lid

open.

• Explaining the benefits of turning off sections of the broiler during low production

periods.

• Suggesting that cooking with the lid down would be beneficial but not expected.

Post-behavioral change monitoring then took place for a period of at least two weeks. The

kitchen staff was taught how to use the thermostatic controls, including proper safety and

cooking operation practices. They were instructed to keep the lid closed when not cooking

on the broiler, and to cook on the broiler with the lid up. The instrumentation package that

was used for field testing of the underfired broiler included a diaphragm-type positive

displacement gas meter with a one-pulse/ft3 output (Figure 2). A data logger was used to

log at a one-minute interval and process and store cumulative gas consumption from the

meter’s pulse outputs.

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Photo Credit: FNI

Photo Credit: FNI

FIGURE 2. FIELD MONITORING GAS METER CONNECTED TO A DATA LOGGER IN THE LAB (LEFT) AND IN THE FIELD (RIGHT)

Broiler operating hours were determined by calculating an hourly input rate using a five-

minute moving average. Anything higher than the pilot moving average was considered

hours that the appliance was on.

Cubic feet were converted into Btu using a representative heating value of 1,025 Btu/scf, a

temperature correction factor of 0.98, and a pressure correction factor of 0.98.

TECHNOLOGY / PRODUCT EVALUATION APPROACH

DESCRIPTION OF EXISTING TECHNOLOGIES

Underfired broiler design is relatively simple. The technology typically incorporates high-

input atmospheric gas burners, using either metal shields or ceramic briquettes to diffuse

their heat (see Figure 3). A heavy-duty grate, which maintains a surface temperature of

600°F or more, is used to cook the food product. Underfired gas broilers typically use two

burners per foot of grate width, rated at 15,000 Btu/h per burner or more. This translates to

an energy input of at least 90,000 Btu/h for a three-foot broiler.

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Photo Credit: Vulcan-Hart Company

FIGURE 3. UNDERFIRED BROILER HEATER SOURCE

Virtually all commercial broilers employ continuous standing pilots to light the burners.

Standard underfired broilers use one standing pilot for every two burners, or one pilot per

linear foot. A typical three-foot underfired broiler containing three standing pilot lights may

consume between 1,500 and 3,500 Btu/h for a three-foot, three-burner broiler, just from

pilots alone.

Broilers do not yet offer temperature feedback to the operator, often leading to arbitrary

adjustment of the burners and over-firing of the appliance (hotter than necessary operating

temperatures). Any unnecessary increase in broiler temperature translates to increased

appliance energy load, increased HVAC load due to additional heat gain to the surrounding

space, and (in most cases) increased operator discomfort Ventilation Considerations

Underfired broilers present a challenge for kitchen ventilation due to the nature of their

particulate emissions and extreme thermal plumes. Even within a diverse cook line, use of

an underfired broiler will drive the ventilation requirements for acceptable capture and

containment of cooking effluent. An inherent characteristic of underfired broilers is that

even during non-cooking periods, the thermal plume generated can challenge a hood’s

ability to capture and contain the effluent—almost as severely as when the broiler is cooking

food product under fully-loaded conditions. While other types of appliances offer

opportunities to reduce ventilation rates during non-cooking periods, underfired broilers are

not as amenable. The FSTC Commercial Kitchen Ventilation lab has reported that the

minimum capture and containment rates for an underfired broiler are 480 cfm/ft (linear foot

9


of the kitchen hood) while cooking, and 360 cfm/ft while idling beneath a five-foot wall

canopy hood.

ENERGY AND TEMPERATURE PERFORMANCE

Understanding the energy performance of standard broilers involves the discussion of

several key topics—including operating and idle energy rates, preheating, and temperature

uniformity. Since almost all broilers are not thermostatically controlled and manufacturers

have established input rates based on peak production (i.e., high broiling temperatures that

minimize cook time), broilers typically consume energy throughout the day at a rate that is

close to their maximum input. Unlike other appliances that consume less energy to maintain

a set temperature once the food load is removed, the end of a broiler cooking event does

not automatically return the broiler to an idle (non-cooking) state. Furthermore, because it

is partially concealed beneath the grid and/or coals, the visibility of a broiler's flame does

not remind the operator to turn the broiler off between loads.

Many standard underfired broilers show a substantial temperature drop towards the front of

the cooking zone. They commonly exhibit a difference of 200°F or more between the hot

spot in the center and the cold spot along the edges of the cooking grate (Figure 4). In

practice, this temperature difference can be used to the operator’s advantage. An

experienced cook will place more delicate items such as chicken or shrimp on the cooler

areas of the broiler, and use the hottest spots for heavier items, such as steaks or chops.

However, this large temperature variation can be a disadvantage for operations that use a

broiler for batch cooking, where larger quantities of uniform food products are being

prepared in a short amount of time.

Photo Credit: California Energy Commission

FIGURE 4. TEMPERATURE UNIFORMITY PLOT FOR THREE-FOOT WIDE STANDARD UNDERFIRED BROILER

Lab testing was conducted on standard broiler technologies, looking at the production

capacity and energy use. Further detail on this testing can be found in the 2013 PIER

Appliance Report.

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DESCRIPTION OF NEW TECHNOLOGIES

LIDDED BROILER DESIGN

FSTC studies performed on conveyor broilers and underfired broilers suggested that the

addition of a lid into the design of an underfired broiler would improve overall appliance

efficiency, while simultaneously improving kitchen ventilation system efficiency, operator

comfort, and satisfaction. There are many appliance performance parameters that would

improve with the use of a lid, including a reduced idle energy rate, faster cook times, and

increased cooking-energy efficiency.

Testing at the FSTC showed that idle rates can be reduced by adding a lid element to an

underfired broiler. The closed lid would also retain radiant heat more effectively in the

cooking zone of the underfired broiler. Similar to the conveyor broiler, which has a semi

enclosed cavity, production capacity would be increased and cook times reduced if cooking

with the lid down. When a lid is added, the underfired broiler would not suffer the same

radiant heat losses that conveyor broilers do because the cavity would be completely

enclosed. It is possible that the improved heat transfer to the food product would make it

feasible to reduce the maximum energy input to the burners (by use of thermostatic

controls) and still achieve the desired cooked product. In this way, a reduction in the

cooking energy rate is expected.

The advanced underfired broiler referenced in this report featured a lid, thermostatic

control, and ceramic infrared burners. FSTC researchers tested the model in laboratory

conditions by applying the American Society for Testing & Materials F1695 Standard Test

Method for Performance of Underfired Broilers. Listed below in Table 1 are the test results.

The energy input rate was measured at 88,500 Btu/h and the pilot energy rate was

measured to be 2,960 Btu/h. The temperature uniformity test using steel discs resulted in

only a 160F temperature differential for the advanced broiler as opposed to a more than

200F differential for standard-efficiency broilers. Tests were then performed with the broiler

in both lid-up and lid-down positions, to quantify the differences. All cooking tests were conducted with ⅓-lb hamburger patties.

TABLE 1. LIDDED UNDERFIRED BROILER LAB TESTING RESULTS

LID UP LID DOWN

Temperature Uniformity 160F differential 160F differential

Preheat Time 16.2 minutes 12.0 minutes

Preheat Energy Consumption 25,600 Btu 19,180 Btu

Heavy-Load Energy Efficiency 44.7 ± 0.7% 52.9 ± 1.3%

Production Capacity 62.7 ± 0.6 lb/h 69.5 ± 0.1 lb/h

Cooking Energy Rate 60,830 Btu/h 57,570 Btu/h

Idle Rate 65,110 Btu/h 58,860 Btu/h

IMPROVED BURNER DESIGN

11


Simple improvements in burner design and heat shields (radiants) can also improve

cooking-energy efficiency rates. Infrared (IR) burners are an advanced burner type that has

been successfully applied to commercial underfired broilers. Several manufacturers

currently offer models using infrared burners. FSTC testing of these broilers as documented

in the 2013 PIER report showed a great deal of improvement over standard atmospheric

burners. These models achieved an average cooking-energy efficiency of 43.5%, compared

with a typical cooking-energy efficiency of 30.3% for standard-efficiency models. Another

advantage of IR burners is that heat is distributed much more evenly across the heated

surface.

VENTILATION CONSIDERATIONS

Reducing the cooking energy rate is important to the overall system efficiency—not only in

terms of appliance gas consumption, but also when examining the impact of the appliance

on the kitchen space. Lidded broilers provide energy savings and reduce heat load to the

kitchen when the lid is closed, reducing ventilation needs as a result. This is significant

because traditionally, broilers are among some of the largest heat loads on the cooking line.

Additionally a broiler that operates at a lower average cooking energy rate would likely

radiate less heat to the kitchen space, thereby improving operator comfort and reducing the

broiler’s impact on the commercial kitchen exhaust system. For ventilation energy savings

to be realized, the kitchen would need a Demand Control Kitchen Ventilation (DCKV) system

with a variable frequency drive (VFD) to modulate hood fan speeds between times when the

lid is up and the lid is down. Ventilation energy savings due to the lidded broiler could only

be counted if fan speeds are driven by the appliance, so the broiler must be the highest

temperature appliance on the line and the existing broiler plume must be captured and

contained to realize savings. Advanced DCKV systems should have the optics calibrated to

sense the smoke reduction associated with the lidded broiler. Other smoke generating

appliances, such as griddles, may trigger the optical sensor, which would discount the fan

reduction associated with the lidded broiler smoke plume.

MAINTENANCE CONSIDERATIONS

The thermostatic controls are composed of standard generic parts, allowing for easy

maintenance and repair. These parts can be easily found and purchased at relatively cheap

prices, saving the user time and money on maintenance issues. The controls also feature a

failsafe mechanism which automatically shuts off gas flow, should the thermostat

malfunction.

ADVANCED BROILER

The advanced broiler featured in this report (Figure 5) incorporates some of the advanced

features described, including thermostatic control and ceramic infrared burner design. The

most unique feature of this model is that it incorporates a lid that may be used during idle

periods, and potentially during cooking.

12


Photo Credit: FNI

FIGURE 5. LIDDED UNDERFIRED BROILER

Laboratory testing was done following the ASTM F1695 test method for heavy-load cooking

to compare the new broiler technology to standard unlidded, atmospheric broilers. While

most broilers can achieve substantially higher operating temperatures, all the broilers were

adjusted to operate at 600°F for the cooking tests. Cooking was performed without a lid for

the broilers with advanced burners, for more direct comparison. The results are shown in

Table 2, where broilers #1–#6 represent conventional designs and broilers #7 and #8

represent advanced (infrared burner) designs. The advanced designs had an average

cooking-energy efficiency of 43.5% versus standard designs at 30.3%. This demonstrates a

relative 44% efficiency improvement (13.2 percentage points). Further information on the

methodology and data analysis for this study can be found in the 2013 PIER Report.

TABLE 2. THREE-FOOT UNDERFIRED BROILER ENERGY PERFORMANCE TESTING RESULTS

TEST

BROILER

RATED INPUT

(BTU/H)

COOKING ENERGY

RATE (BTU/H)1 HEAVY-LOAD COOKING-ENERGY EFFICIENCY (%)

PRODUCTION

CAPACITY (LB/H)

1 120,000 72,500 32% 57

2 105,000 78,300 31% 58

3 105,000 64,400 28% 46

1Cooking energy rate represents the energy consumption rate required to maintain 600°F in the cooking

zone.

13


4 87,000 57,200 34% 48

5 105,000 82,400 29% 58

6 105,000 83,400 28% 56

7 105,000 64,600 41% 66

8 105,000 54,200 46% 63

These cooking-energy efficiencies were determined from cooking discrete (heavy) loads of

hamburger patties. However, the real-world (in-kitchen) efficiency drops dramatically as the

energy consumed by the broiler during periods of non-cooking (idle) is factored into the

denominator of the energy-efficiency equation. For example, a gas-underfired broiler used

to cook 100 pounds of food over an eight-hour period consumed 600,000 Btu of energy as

referenced in the 2013 PIER Appliance Report. Based on average of 300 Btu per pound of

food cooked, the total energy actually delivered to the food product over the eight-hour

period would be approximately 30,000 Btu. This translates to a real-world energy utilization

efficiency of only 5% because the rest of the time is usually spent in idle mode at the same

input rate. It is clear that a tremendous opportunity to improve overall appliance energy

efficiency exists in developing new broiler designs and usage patterns—particularly designs

that would reduce energy consumption during idle times.

Production capacity indicates the maximum amount of food (by weight) that can be cooked

on a broiler in a given amount of time. Since the ASTM test method uses hamburger patties

for the test product, production capacity is the weight, in pounds, of hamburger patties that

can be cooked by the broiler in one hour (lb/h). This number is dependent on the size of the

broiler and the length of the cook time. Table 2 shows the range in production capacities for

three-foot underfired broilers. Comparing the average production capacity of advanced

burner designs in Table 2 (units 7 and 8) with that of conventional burners (units 1-6)

indicates that a 20% improvement in production capacity can be realized with infrared

burners, which translates to faster cook times.

In addition to reducing heat gain to the kitchen space, covering the broiler with a lid will

reduce the rate that energy is consumed by the broiler while still maintaining a hot cooking

grate. Testing at the FSTC has shown that, when calibrated to 600°F, an underfired broiler

will realize a reduction of over 17% in its idle energy consumption rate (from 65,110 Btu/h

to 53,860 Btu/h on average) by simply covering the broiler grate with an improvised lid

during non-cooking periods. The tests further showed a heat gain reduction of 27% (from

6,000 to 4,400 Btu/h on average) when the broiler was covered. An ASHRAE research paper

(Owen 2013) found a conventional un-lidded broiler with a non-infrared burner operating at

an idle input rate of 73,900 Btu/h had a radiant heat gain of 9,000 Btu/h. This resulted in a

51% heat gain reduction when switching from a conventional un-lidded broiler to the IR

broiler idling with the lid closed. Thus, a lidded broiler calibrated to 600°F can maintain that

temperature while using much less energy and radiating less heat to the kitchen. The

reduced idle energy rate could also be used in conjunction with a demand ventilation control

system to reduce the exhaust airflow during non-cooking periods, thereby increasing energy

savings even further.

14


FIELD ANALYSIS, RESULTS, AND RECOMMENDATIONS

NORM’S PLACE (DANVILLE, CA)

TECHNICAL APPROACH

SITE DESCRIPTION

Norm’s Place is a restaurant and bar specializing in cooking American pub food. Most of the

product is cooked to order on a broiler. This establishment is famous for its burgers, which

are ground in-house and cooked on the broiler. The restaurant is located in Danville’s

historic downtown area. The eatery is open Tuesday through Sunday from 11 a.m. to 10

p.m. or later. Norm’s Place usually has a steady stream of customers during later hours of

the day and is usually very busy after 5 p.m. The dining room and front of Norm’s is shown

in Figure 6.

Photo Credit: FNI Photo Credit: Google

FIGURE 6. NORM'S PLACE EXTERIOR (LEFT) AND INTERIOR BAR AND DINING AREA (RIGHT)

SITE ASSESSMENT

The restaurant’s kitchen consultant specified a several-decades-old conventional three-foot

wide, open underfired broiler with non-thermostatic controls, shown in Figure 7. The

maximum input of the broiler was 120 kBtu/h with six adjustable 20 kBtu/h radiant burners.

On weekdays, the broiler was preheated around 10 a.m. and turned off around 10 p.m. The

staff did not turn off the pilot at night.

BASELINE RESULTS

Gas metering equipment was installed on the existing broiler shown in Figure 7 and

monitoring commenced for several weeks. After the data was analyzed for this monitoring

period, 49 representative days were selected for the baseline period from February-April.

It was determined that the average time the broiler was on per day during the entire

baseline monitoring period was 12.53 hours, including weekends. Throughout the day, there

was minimal adjustment to the burner input rates by the user, and the average input rate

was 77 kBtu/h. The broiler had a 1.9 kBtu/h standing pilot. A typical weekday profile is

shown in Figure 8.

15


Photo Credit: FNI

FIGURE 7. EXISTING BROILER AT NORM'S PLACE

Source: FNI

FIGURE 8. THURSDAY FEB. 28, TYPICAL ENERGY PROFILE OF EXISTING BROILER AT NORM’S PLACE

The average daily gas consumption of the existing broiler was 9.59 therms per day,

averaged over 49 days of monitoring (excluding holidays and Mondays). The average

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operating time was 12.53 hours per day. Daily energy use was fairly consistent, ranging

from just under eight to eleven therms depending on the time of the week (Friday and

Saturday being the busiest days in terms of broiler operating hours). Broiler energy use and

operating hours were summarized using the scatter plots in Figure 9 to show day-to-day

operational variation. As can be seen from the graph, this variation was minimal in terms of

the broiler’s daily hours of operation. Variance in energy use as a function of hours of

operation was caused by burner modulation by the broiler operator. The graph also features

a non-zero energy value at zero hours of operation, which accounts for the energy used by

the pilot light that was never turned off. The broiler pilot energy was 2.0 kBtu/h, or 0.5

therms/day. Broiler hours of operation were defined as time where energy use was above

the pilot rate, to eliminate pilot noise.

Source: FNI

FIGURE 9. EXISTING BROILER ENERGY USE AND HOURS OF OPERATION AT NORM’S PLACE

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17


REPLACEMENTS RESULTS

Photo Credit: FNI

FIGURE 10. REPLACEMENT BROILER AT NORM’S PLACE

The replacement broiler at Norm’s is shown in Figure 10 above. Several weeks of data were

analyzed; 32 days were used for replacement monitoring from September through October.

The average time the replacement lidded broiler was on per day during the entire

monitoring period was 11.86 hours, including weekends. The operator used different

sections of the broiler, turning them on or off based on the production demands. The

average input rate during the monitoring period was 73 kBtu/h. A typical weekday profile is

shown in Figure 11.

Source: FNI

FIGURE 11. THURSDAY SEPTEMBER 19, TYPICAL ENERGY PROFILE OF REPLACEMENT BROILER AT NORM’S PLACE

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As illustrated by energy fluctuations in the plot, the broiler automatically turned its burners

on and off throughout the day in response to the use of the lid and the thermostat setpoint.

This caused the average input rate to be lower than the conventional broiler. The average

daily consumption of the thermostatically-controlled replacement broiler was 7.51 therms

per day, averaged over 32 days of monitoring (excluding holidays and Mondays). The daily

energy use ranged from six to nine therms, depending on the day of the week (Friday

typically being the busiest day in terms of broiler operating hours). The average operating

time was 11.86 hours per day. The broiler pilot energy was 2.0 kBtu/h, or 0.5 therms/day.;

staff never turned off the pilot at night. Broiler energy use and operation hours are

summarized using the scatter plots in Figure 12 to show day-to-day operational variation.

Source: FNI

FIGURE 12. REPLACEMENT BROILER ENERGY USE AND HOURS OF OPERATION AT NORM'S PLACE

The replacement broiler reduced energy consumption by 22% (from 9.59 to 7.51 therms

per day) through more efficient infrared burners. Hours of broiler operation stayed

essentially the same, but closing the broiler lid significantly reduced the idle energy. The lid

minimized heat loss while the broiler was left idle, which allowed the thermostatic controls

to maintain idle temperature at lower burner rates. In a cook-to-order restaurant scenario

such as this, a large portion of the “on” time is spent in idle mode, creating an opportunity

to generate significant savings with the lidded broiler. These savings are illustrated clearly

in Figure 13, which overlays typical daily usage patterns of the original and replacement

broilers. Energy savings are marked by the occasional decreases in input rate,

corresponding to the activation of the thermostatic controls when the broiler lid is placed

down in idle mode. Figure 14 shows the regression lines taken from Figure 9 (Existing

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Broiler) and Figure 12 (Lidded Broiler) based on the daily operating hours and energy use.

The slopes of the existing and replacement broiler are quite different; the energy use is

directly proportional to the hours of operation for both broiler configurations. This shows

that the replacement broiler has greater energy savings as it is used more. For the typical

Norm’s hours of operation, energy savings of two therms per day (22%) were realized

through the more energy-efficient lidded broiler.

Source: FNI

FIGURE 13. ENERGY PROFILE COMPARISON: EXISTING TO REPLACEMENT BROILER AT NORM’S PLACE

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Existing Broiler Replacement Broiler

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Source: FNI

FIGURE 14. DAILY ENERGY REGRESSION COMPARISON AT NORM’S PLACE: EXISTING TO REPLACEMENT BROILER

CUSTOMER FEEDBACK/RECOMMENDATIONS

This project was a successful demonstration of the potential savings from replacing

conventional underfired broilers with a more efficient lidded version. The manager and chefs

at Norm’s were happy with the broiler’s cooking performance and the energy savings the

appliance provided.

THE GROWLER (DANVILLE, CA)

TECHNICAL APPROACH

SITE DESCRIPTION

The Growler is a lively restaurant and bar located in the heart of Danville. The restaurant is

open Tuesday through Sunday from 11 a.m. to 11 p.m., and is known best for their burgers

and wide selection of craft beers. With the focus directed towards their drink selection, The

Growler offers only a limited menu of food options. Much of this food—including burgers,

sausages, chicken, and vegetables—is cooked on the broiler, which is the primary appliance

in the kitchen.

SITE ASSESSMENT

The appliance to be replaced was a conventional three-foot wide, open underfired broiler

with non-thermostatic controls, shown in Figure 15. The maximum input of the broiler was

114 kBtu/h with six adjustable 19 kBtu/h radiant burners. On weekdays, the broiler was

preheated around 11 a.m. and turned off around 9 p.m. The staff did not turn off the pilot

at night.

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BASELINE RESULTS

The Growler restaurant opened in an existing facility where the cooking equipment was

inherited from the previous owner. The old broiler, with non-thermostatic controls, was

refurbished and installed before the restaurant opening. The maximum input of the broiler

was 114 kBtu/h, with six adjustable 19 kBtu/h radiant burners. The gas metering equipment

was installed on the standard broiler and monitoring commenced for several weeks. After

the data was analyzed for this monitoring period, 27 representative days were selected for

the baseline period from May through June.

Photo Credit: FNI

FIGURE 15. EXISTING BROILER CARRIED OVER FROM THE PREVIOUS OWNERS TO THE GROWLER

The standard broiler specifications are highlighted in yellow in Table 3 below.

22


TABLE 3. GROWLER’S EXISTING BROILER SPECIFICATIONS

GAS TYPE: Natural

Manifold Pressure: 6.0" WC

MODELS: BURNERS BTU/HR (KW)

UFLC-18R 2 38,000 (11.1)

UFLC-24R 4 76,000 (22.3)

UFLC-30R 5 95,000 (27.8)

UFLC-36R 6 114,000 (33.4)

UFLC-48R 8 152,000 (44.5)

UFLC-60R 11 290,000 (61.2)

UFLC-72R 13 247,000 (72.4)

On weekdays, the broiler was preheated around 11 a.m. and turned off around 9 p.m. The

average time the broiler was on per day during the entire baseline monitoring period was

11.27 hours, including weekends. Throughout the day, the operator would often use four out of six burners, and the input controls would not be turned on past ⅔ of full input. One

linear foot of the broiler was usually turned off. The baseline input knob positions are shown

in Figure 16. The average input rate was 57 kBtu/h (50% of full input) during the

restaurant’s cooking hours. Most conventional broilers are on at more than the half the

input and operators usually do not adjust the input rate throughout the day. However, in

this particular location, the operator was continuously adjusting the input rate in order to

cook more delicate vegetables and poultry. The broiler had a 2.3 kBtu/h standing pilot; the

staff would leave the pilot on at night. A typical cooking input profile is shown in Figure 17.

Source: FNI

FIGURE 16. EXISTING BROILER INPUT KNOB SETTINGS AT THE GROWLER

23


Source: FNI

FIGURE 17. WEDNESDAY MAY 7, TYPICAL ENERGY PROFILE OF EXISTING BROILER AT THE GROWLER

The average daily gas consumption of the standard broiler was 6.56 therms per day,

averaged over 27 days of monitoring (excluding holidays). The daily energy use ranged

from five to nine therms depending on the time of the week, with Friday and Saturday being

the heaviest days of broiler operating hours. For a better understanding of day-to-day

operational variation, broiler energy use and operating hours are shown in Figure 18.

Variance in energy use as a function of hours of operation was caused by burner modulation

by the broiler operator.

Source: FNI

FIGURE 18. EXISTING BROILER ENERGY USE AND HOURS OF OPERATION AT THE GROWLER

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24


REPLACEMENTS RESULTS

Several weeks of data were analyzed; 20 days were used for replacement monitoring from

June through July. The kitchen setup for the replacement broiler is shown in Figure 19.

Photo Credit: FNI

FIGURE 19. REPLACEMENT BROILER INSTALLED ON COOK LINE AT THE GROWLER

The average time the replacement lidded broiler was on per day during the entire

monitoring period was 9.1 hours, including weekends. The average input rate was 40

kBtu/h; throughout the day the user adjusted the input rate for the burners, and never had

them on at full input. A typical weekday profile is shown in Figure 20.

Source: FNI

FIGURE 20. THURSDAY JUNE 19, TYPICAL ENERGY PROFILE OF REPLACEMENT BROILER AT THE GROWLER

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on and off throughout the day in response to the use of the lid and the thermostat setpoint

(shown in Figure 21). This caused the average input rate to be lower than the conventional

broiler. The average daily consumption of the thermostatically-controlled replacement

broiler was 3.62 therms per day, averaged over 20 days of monitoring (excluding holidays).

The daily energy use ranged from three to five therms, depending on the day of the week

(Friday and Saturday being the busiest days in terms of broiler operating hours). The broiler

pilot energy was 2.0 kBtu/h, or 0.5 therms/day; staff never turned off the pilot at night.

Broiler energy use and operation hours are summarized using the scatter plots in Figure 22

to show day-to-day operational variation. The restaurant owner was very pleased with the

performance of the new broiler (Figure 23) and said that they would be cooking burgers on

the broiler rather than the griddle. The operator was previously using the broiler for

vegetables and chicken only, so adding the burgers to the cook load was estimated to

increase the production load of the new broiler by 50%.

Photo Credit: FNI

FIGURE 21. REPLACEMENT THERMOSTATICALLY-CONTROLLED BROILER THERMOSTAT SETPOINT AT THE GROWLER

26


Source: FNI

FIGURE 22. REPLACEMENT BROILER ENERGY USE AND HOURS OF OPERATION AT THE GROWLER

Photo Credit: FNI

FIGURE 23. REPLACEMENT THERMOSTATICALLY-CONTROLLED BROILER INFRARED BURNERS AT THE GROWLER

When gathering data, it was noticed that often the lid was not closed during idle operation.

The operator had only one of the three burners on, so the energy savings were attributed

more to the higher-efficiency infrared burners and to a low 350°F thermostat setpoint. FSTC

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staff highlighted this fact to the cooks and the manager, explaining the added energy-saving

benefits of leaving the lid closed whenever possible, which would result in the burners

cycling less frequently. After this discussion, closing the lid became a more standard policy

at The Growler.

After these behavioral changes were adopted, The Growler saw their replacement broiler

energy reduced from 3.62 therms per day to 3.05 therms per day, averaged over another

39 days of monitoring (excluding holidays). The time the broiler was on was reduced from

9.10 to 7.38 hours per day. The operator had mentioned at the beginning of this study that

they were planning to move towards a batch-cooking approach, where more food would be

cooked simultaneously to reduce the broiler’s on-time. The improved cooking performance

of the replacement broiler due to the IR broilers complemented The Growler’s new batch-

cooking strategy. The graph in Figure 24 below shows that the slopes of the two regression

lines are very similar, meaning that the behavioral changes mostly affected length of time

the broiler was on. This is illustrated by the location of the data point clusters, where the

post-behavioral data points are centered around 7.38 hours and the pre-behavioral data

points are centered around 9.10 hours.

Source: FNI

FIGURE 24. ENERGY USE COMPARISON AT THE GROWLER: PRE- TO POST-BEHAVIORAL CHANGE AT THE GROWLER

The replacement broiler reduced energy by 45% (from 6.56 to 3.62 therms per day)

through a lower thermostat setpoint and more efficient infrared burners. Discussions with

the operators on behavioral changes resulted in closing the lid more often, which resulted in

energy savings of additional 16% (from 3.62 to 3.05 therms per day). Closing the lid

reduced the idle energy, and in a cook-to-order restaurant scenario such as this, a majority

of the “on” time was spent in idle mode. The overlaid comparison graphs in Figure 25 clearly

illustrate the reduced energy use when the lid was used. Figure 26 shows the regression

lines taken from Figure 18 (Existing Broiler) and Figure 24 (Post-Behavioral Replacement

Broiler), based on the daily operating hours and energy use.

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Source: FNI

FIGURE 25. ENERGY PROFILE COMPARISON AT THE GROWLER: EXISTING TO REPLACEMENT BROILER (AFTER

BEHAVIORAL CHANGES)

Source: FNI

FIGURE 26. DAILY ENERGY REGRESSION COMPARISON AT THE GROWLER: EXISTING TO REPLACEMENT BROILER (AFTER

BEHAVIORAL CHANGES)



that the replacement broiler has greater energy savings as it is used more. Energy savings

at The Growler were realized through the more energy-efficient lidded broiler, as well as

behavioral changes, to reduce daily hours of operation of the broiler. This resulted in a 54%

reduction, or three therms per day.

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The restaurant owner and operator were both pleased with the performance of the new

broiler, both in energy use and cooking ability. With this performance upgrade, burger

cooking will now be switched from the griddle to the broiler. The emphasis on behavioral

changes and the resulting energy savings also inspired a more energy-conscious mindset.

The operator mentioned that they were moving towards a batch-cooking approach, where

more food would be cooked simultaneously to reduce the broiler’s on-time.

SIDEBOARD (DANVILLE, CA)

TECHNICAL APPROACH

SITE DESCRIPTION

Sideboard is a New American restaurant and café recently relocated to the heart of Danville.

The restaurant is open Tuesday through Saturday from 8 a.m. to 9 p.m., and is best known

for their breakfast and lunch fare. Sideboard uses their broiler for cooking steaks and

chicken, but one of their most popular options is their burger, which is branded with their

initials. This results in significant broiler use, making it a strong candidate for appliance

replacement.

SITE ASSESSMENT



90 kBtu/h with six adjustable 15 kBtu/h radiant burners. The broiler was typically preheated

around 7 a.m. and turned off around 9:30 p.m. The staff did not turn off the pilot at night.

BASELINE RESULTS

DATA COLLECTION AND ANALYSIS

Sideboard’s kitchen consultant specified a conventional three-foot wide, open, underfired

broiler with non-thermostatic controls, which was installed before the restaurant opening.

The gas metering equipment was installed on the standard broiler and monitoring

commenced for several months. After several months of data were analyzed, 59 days were

selected for the baseline monitoring from April through June.

30


Photo Credit: FNI

FIGURE 27. EXISTING BROILER AT SIDEBOARD


TABLE 4. SIDEBOARD’S EXISTING BROILER SPECIFICATIONS

MODEL NO. WIDTH DEPTH NO. OF BURNERS TOTAL BTU SHIP WEIGHT

RRB-12 12" 6.0”WC 1 15,000 170 lb

RRB-18 18" Btu/hr (kW) 3 45,000 235 lb

RRB-24 24" 38,000 (11.1) 4 60,000 300 lb

RRB-30 30" 76,000 (22.3) 5 75,000 340 lb

RRB-36 36" 95,000 (27.8) 6 90,000 383 lb

RRB-48 48" 114,000 (33.4) 8 120,000 460 lb

RRB-60 60" 152,000 (44.5) 10 150,000 510 lb

RRB-72 72" 290,000 (61.2) 12 180,000 670 lb

The broiler was typically preheated around 7 a.m. and turned off around 9:30 p.m. The

average time the broiler was on per day during the entire baseline monitoring period was

14.31 hours including weekends. Throughout the day the operator would adjust all six

burners and the input controls would be turned on close to ¾ of full input. The average

input rate was 75 kBtu/h (83% of full input) during the restaurant’s cooking hours. In this

particular location the operator did not adjust the input rate, regardless of whether there

was any cooking done on the broiler. The broiler had a 2.0 kBtu/h standing pilot; the staff

would leave the pilot on at night. A typical cooking input profile is shown in Figure 28.

31


Source: FNI

FIGURE 28. WEDNESDAY MAY 7, TYPICAL ENERGY PROFILE OF EXISTING BROILER AT SIDEBOARD


averaged over 59 days of monitoring (excluding holidays). The daily energy use was very

consistent and ranged from nine to eleven therms depending on the time of the week, with

Friday and Saturday being the busiest days in terms of broiler operating hours. Broiler

energy use and operating hours were shown in Figure 29 for a better understanding of day-

to-day operational variation. Variance in energy use as a function of hours of operation was

caused by burner modulation by the broiler operator. The graph also features a non-zero

energy value at zero hours of operation, which accounts for the approximately 2.0 kBtu/h,

or 0.5 therm/day; staff never turned off the pilot at night. Hours of operation were defined

as time where energy use was above the pilot rate, to eliminate pilot noise.

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Source: FNI

FIGURE 29. EXISTING BROILER ENERGY USE AND HOURS OF OPERATION AT SIDEBOARD

REPLACEMENT RESULTS

The kitchen setup for the new replacement broiler is shown in Figure 30. The thermostat

settings are shown in Figure 31. Several days of data were analyzed; Ten days were used

for replacement monitoring in the month of June. The average time the replacement lidded

broiler was on per day during the entire monitoring period was 14.56 hours, including

weekends. Throughout the day, the user adjusted the input rate for the burners and never

had them on full input. The average input rate was 68 kBtu/h.

Photo Credit: FNI

FIGURE 30. REPLACEMENT LIDDED, THERMOSTATICALLY-CONTROLLED BROILER INSTALLED ON SIDEBOARD COOK LINE

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Photo Credit: FNI

FIGURE 31. LIDDED BROILER THERMOSTAT AT SIDEBOARD SET FOR 400°F

A typical weekday profile is shown in Figure 32 below.

Source: FNI

FIGURE 32. WEDNESDAY JUNE 14, TYPICAL ENERGY PROFILE OF REPLACEMENT BROILER AT SIDEBOARD


on and off throughout the day in response to use of the lid and the thermostat setpoint.

Over the first two weeks of replacement broiler monitoring, this caused the average input

rate to be lower than the conventional broiler, but not by much (68 kBtu/h vs. 75 kBtu/h).

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The average daily consumption of the replacement thermostatically-controlled broiler was

9.94 therms per day, averaged over the first ten days of monitoring after installation. The

daily energy use ranged from seven to ten therms, depending on the day of the week

(Friday and Saturday being the busiest days in terms of broiler operating hours). The broiler

pilot energy was 2.0 kBtu/h, or 0.5 therm/day; staff never turned off the pilot at night.

Broiler energy use and operating hours were summarized using the scatter plots in Figure

33 to show day-to-day operational variation. The restaurant owner was very pleased with

the performance of the new broiler. However, he was surprised by the small energy

reduction of 7%.

Source: FNI

FIGURE 33. REPLACEMENT BROILER ENERGY USE AND HOURS OF OPERATION AT SIDEBOARD

When gathering this initial replacement broiler data, it was noticed that often the lid was not

closed during idle operation. The operator had all the burners set for maximum, and the

thermostat was typically set at 400°F or above. This high thermostat setting did not allow

the broiler to cycle when the lid was open. With the operator leaving the lid open and the

input knobs set to maximum, the broiler idled at an input rate similar to when it was used

for cooking. This meant there was still opportunity for additional energy savings. After

having a talk with the cooks and the manager, they were instructed to close the lid more

often, as well as reduce the thermostat setpoint to 350°F (Figure 34).

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Photo Credit: FNI

FIGURE 34. REPLACEMENT THERMOSTATICALLY-CONTROLLED BROILER THERMOSTAT SETPOINT AT SIDEBOARD

Behavioral changes resulted in an energy reduction from 9.94 therms per day to 8.80

therms per day, averaged over another 52 days of monitoring (excluding holidays). The

time the broiler was on was slightly reduced, from 14.56 to 13.83 hours per day. The graph

in Figure 35 below shows that the slopes of the two regression lines are very similar,

meaning that the savings from the behavioral changes were mostly due to cook time

reduction. This can be seen clearly by the orange intersection lines on the graph, which

follow the daily usage hours.

Source: FNI

FIGURE 35. ENERGY USE COMPARISON: PRE- TO POST-BEHAVIORAL CHANGE AT SIDEBOARD

Initially after installation, the replacement broiler reduced energy by 7% (from 10.67 to

9.94 therms per day) through a lower thermostat setpoint and more efficient infrared

burners. After discussing what behavioral changes the operator could make, the lid was

closed more often, resulting in an additional 11% in energy savings (from 9.94 to 8.80

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Pre Behavioral Replacement Broiler Post Behavioral Replacement Broiler

Pre Behavioral Energy Use

Post Behavioral Energy Use

36


therms per day). The average input rate of the broiler dropped down to 59 kBtu/h, while the

operating time remained almost the same. Closing the lid reduced the idle energy, and in a

cook-to-order restaurant scenario such as this, a majority of the “on” time was spent in idle

mode. The overlaid comparison graphs in Figure 36 clearly illustrate the reduced energy use

when the lid was used. Figure 37 shows the regression lines taken from Figure 29 (Standard

Broiler) and Figure 35 (Post-Behavioral Lidded Broiler), based on the daily operating hours

and energy use.

Source: FNI

FIGURE 36. ENERGY PROFILE COMPARISON: EXISTING TO REPLACEMENT BROILER (AFTER BEHAVIORAL CHANGES)

Source: FNI

FIGURE 37. DAILY ENERGY REGRESSION COMPARISON: EXISTING TO REPLACEMENT BROILER (AFTER BEHAVIORAL

CHANGES)

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37




that the replacement broiler has greater energy savings as it is used more. Energy savings

at Sideboard were realized through the more energy-efficient lidded broiler, as well as

behavioral changes, to reduce daily hours of operation of the broiler. This resulted in an

18% reduction in energy use, or two therms per day. 11% savings can be attributed to the

behavioral changes.


The Sideboard owners and chefs were very pleased with the replacement broiler. Though

the energy savings weren’t initially quite as significant as expected, the cooking

performance and temperature uniformity of the lidded broiler were lauded. Implementing

behavioral changes increased energy savings to a satisfactory level.

This project was a successful demonstration of the potential savings from replacing

conventional underfired broilers with a more efficient lidded version. It also validates the

significance of optimizing behavioral changes in staff broiler operation. Results suggest that

these savings would be most significant at establishments with long operating hours and

extended idle periods.

ESIN (DANVILLE, CA)

TECHNICAL APPROACH

SITE DESCRIPTION

Esin (Figure 38) is a fine-dining restaurant and bar located in downtown Danville,

specializing in American cuisine with Mediterranean twists. The restaurant is open seven

days a week from 11:30 a.m. to either 9 p.m. or 10 p.m., depending on the day. Esin’s

appliances typically spend a large amount of time in idle mode, since kitchen output is

relatively lower volume. Coupled with the restaurant’s long hours of operation, this signaled

a strong opportunity to generate energy savings.

Photo Credit: FNI Photo Credit: Esin

FIGURE 38. ESIN EXTERIOR (LEFT) AND INTERIOR BAR (RIGHT)

38


SITE ASSESSMENT



114 kBtu/h with six adjustable 19 kBtu/h radiant burners. The broiler was typically

preheated around 9:30 a.m. and turned off around 9:30 or 10:30 p.m., depending on the

day. The staff did not turn off the pilot at night.

BASELINE RESULTS

Gas metering equipment was installed on the original broiler and monitoring commenced for

several weeks. After the data was analyzed for this monitoring period, 29 representative

days were selected for the baseline period from July through August.

It was determined that the average time the broiler was on per day during the entire

baseline monitoring period was 12.83 hours, including weekends. Throughout the day, there

was minimal user adjustment to the burner input, and the average input rate was 84

kBtu/h. The broiler had a 1.9 kBtu/h standing pilot.

Photo Credit: FNI

FIGURE 39. EXISTING BROILER AT ESIN


39


TABLE 5. ESIN’S EXISTING BROILER SPECIFICATIONS

GAS TYPE: Natural

Manifold Pressure: 6.0" WC

MODELS: BURNERS BTU/HR (KW)

UFLC-18R 2 38,000 (11.1)

UFLC-24R 4 76,000 (22.3)

UFLC-30R 5 95,000 (27.8)

UFLC-36R 6 114,000 (33.4)

UFLC-48R 8 152,000 (44.5)

UFLC-60R 11 290,000 (61.2)

UFLC-72R 13 247,000 (72.4)

A typical weekday profile is shown in Figure 40 below.

Source: FNI

FIGURE 40. WEDNESDAY JULY 30, TYPICAL ENERGY PROFILE OF EXISTING BROILER AT ESIN


averaged over 29 days of monitoring (excluding holidays). The daily energy use ranged

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from nine to twelve therms depending on the time of the week, with Friday and Saturday

typically being the heaviest days of broiler operating hours. For a better understanding of

day-to-day operational variation, broiler energy use and operating hours are shown in

Figure 41.

Source: FNI

FIGURE 41. EXISTING BROILER ENERGY USE AND HOURS OF OPERATION AT ESIN

REPLACEMENT RESULTS

Photo Credit: FNI

FIGURE 42. REPLACEMENT LIDDED, THERMOSTATICALLY-CONTROLLED BROILER INSTALLED ON COOK LINE AT ESIN

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Several weeks of data were analyzed; 15 days were used for replacement monitoring from

August through September. The kitchen setup for the new replacement broiler is shown in

Figure 42. The average time the replacement lidded broiler was on per day during the entire

monitoring period was 12.49 hours, including weekends. The average input rate was 64

kBtu/h. A typical weekday profile is shown in Figure 43.

Source: FNI

FIGURE 43. MONDAY SEPTEMBER 1, TYPICAL ENERGY PROFILE OF REPLACEMENT BROILER AT ESIN


on and off throughout the day in response to the use of the lid and the thermostat setpoint.

This caused the average input rate to be lower than the conventional broiler. The average

daily consumption of the thermostatically-controlled replacement broiler was 7.98 therms

per day, averaged over 15 days of monitoring (excluding holidays). The daily energy use

ranged from six to ten therms, depending on the day of the week (Friday and Saturday

being the busiest days in terms of broiler operating hours). The broiler pilot energy was 2.0

kBtu/h, or 0.5 therm/day; staff never turned off the pilot at night. Broiler energy use and

operation hours are summarized using the scatter plots in Figure 44 to show day-to-day

operational variation.

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Source: FNI

FIGURE 44. REPLACEMENT BROILER ENERGY USE AND HOURS OF OPERATION AT ESIN

Photo Credit: FNI

FIGURE 45. REPLACEMENT THERMOSTATICALLY-CONTROLLED BROILER INFRARED BURNERS AT ESIN

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The replacement broiler reduced energy by 26% (from 10.73 to 7.98 therms per day)

through a lower thermostat setpoint and more efficient infrared burners (Figure 45). Hours

of broiler operation stayed essentially the same, but closing the broiler lid significantly

reduced the idle energy. The lid minimized heat loss while the broiler was left idle, which

allowed the thermostatic controls to maintain idle temperature at lower burner rates. For

Esin, a large portion of the “on” time is spent in idle mode. This thus creates an opportunity

to generate significant savings with the lidded broiler. These savings are illustrated clearly

in Figure 46, which overlays typical daily usage patterns of the original and replacement

broilers. Energy savings are marked by the occasional decreases in input rate,

corresponding to the activation of the thermostatic controls when the broiler lid is placed

down in idle mode. The frequent thermostatic control modulation also causes variation in

day by day energy use, and accounts for the relative non-linearity of the data points for

Figure 44. Figure 47 shows the regression lines taken from Figure 41 (Existing Broiler) and

Figure 44 (Lidded Broiler) based on the daily operating hours and energy use.

Source: FNI

FIGURE 46. ENERGY PROFILE COMPARISON AT ESIN: EXISTING TO REPLACEMENT BROILER

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Source: FNI

FIGURE 47. DAILY ENERGY REGRESSION COMPARISON AT ESIN: EXISTING TO REPLACEMENT BROILER



that the replacement broiler has greater energy savings as it is used more. Replacing the

existing broiler with a more energy-efficient lidded broiler at Esin resulted in a 26%

reduction in broiler energy use, or about three therms per day in Esin’s daily gas

consumption.

VENTILATION OBSERVATIONS

Lidded broilers provide direct energy savings in broiler use, as well as reduced heat load to

the kitchen when the lid is closed. This is significant because traditionally, broilers are

among some of the largest heat loads on the cooking line, and thus are often the biggest

drivers for high exhaust ventilation rates. For their kitchen, Esin had a DCKV system with

temperature sensors in the exhaust duct. This system included optical sensors, which detect

smoke and ramp up the exhaust fan (Figure 48).

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Source: FNI

FIGURE 48. DCKV OPTICAL SENSOR INSIDE ESIN’S HOOD

Lidded broilers have the potential to reduce the exhaust ventilation when paired with a

DCKV system. Exhaust fan energy is directly related to supply fan energy, as well as any

energy associated with conditioning that makeup air. Exhaust fan energy was monitored for

two weeks at Esin through true power readings inside the breaker panel, with the existing

broiler installed, to provide baseline data. The exhaust fan operated at 2,500 W for most of

the day. An average daily fan energy profile with the existing broiler is shown in Figure 49.

46


Source: FNI

FIGURE 49. ESIN’S EXHAUST FAN POWER CONSUMPTION

Analysis of the ventilation data at Esin showed that the DCKV system was not operating

properly; the exhaust fan was operating at a nearly constant rate, without any fan speed

modulation. After further investigation, it was discovered that the DCKV controls were set to

operate at 50% for an exhaust duct temperature of 75°F and at 100% for a temperature of

110°F (Figure 50).

Source: Melink Operation Manual

FIGURE 50. ESIN’S DCKV SYSTEM SETTINGS

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Since Esin had a large hood with three to six burner ranges, a low efficiency fryer and a

broiler, the heat generated by these appliances resulted in duct temperatures that

consistently exceeded 110°F. Given the DCKV settings, this meant that the fan was

constantly operating at 100% speed. Thus, The DCKV system could not generate any

energy savings. Since the open broiler generated the most heat, a lidded replacement would

potentially lower the duct temperature to allow the DCKV system to modulate and realize

exhaust fan energy savings.

Though the chefs at Esin were pleased with the performance and cooking uniformity of the

lidded broiler, the 4-foot-deep ventilation hood failed to capture and contain the smoke

plume. Figure 47 illustrates the relative positioning of the lidded broiler and the ventilation

hood. The geometry of the lidded broiler caused the smoke plume to bend slightly outwards

towards the operator, as opposed to straight up. This difference was enough to impede

proper ventilation, causing smoke buildup in the kitchen during times of high-load broiler

operation. Another contributing factor to the spillover was the low ventilation system’s low

exhaust rate.

This was the first time this problem was encountered in this study. Most of the other three

sites where the lidded broiler was installed had a 4.5-foot-deep kitchen hood, and could

adequately capture and contain the broiler effluent.

Rather than abandoning the more energy-efficient lidded broiler, efforts were first made to

modify the ventilation system. Since the maximum speed of the DCKV system was

insufficient for capturing and containing the lidded broiler’s smoke plume, attempts to

increase the ventilation rate were made by increasing the fan pulley diameter, which

increased the flow rate by 22%. An average daily fan energy profile with the lidded broiler

and increased fan speed is shown in Figure 51.

Source: FNI

FIGURE 51. AVERAGE DAILY FAN ENERGY PROFILE AT ESIN

The increase in fan speed from the pulley adjustment was insufficient to fully solve the

effluent spillover problem, and resulted in increased energy use—mitigating the

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adjustment’s positive effects. Given their ventilation system, the lidded broiler was not

suitable for their kitchen needs, and Esin ultimately decided to reinstall their previous

broiler. Future investigations may be made into new energy efficiency broiler technologies

at this site that do not affect smoke plume.

CUSTOMER FEEDBACK/ RECOMMENDATIONS

The staff at Esin were pleased with the energy savings and cooking performance of the new

broiler. Unfortunately, the ventilation issues caused smoke to build up in the kitchen during

the busy hours of Friday and Saturday. This problem was large enough to offset the benefits

of the lidded broiler, and Esin switched back to their conventional broiler.

The broiler performed as expected, yielding strong cooking results and energy savings.

However, it was incompatible with the current kitchen setup. This project brought to light a

new issue regarding lidded broilers that must be further explored. Future investigations

should be made into new energy efficient broiler technologies that do not affect smoke

plume.

Increasing the exhaust fan ventilation speed through mechanical pulley adjustment

improved the capture of the plume of the lidded broiler. However, this adjustment did not

fully contain the plume while the lid was open with full-load cooking, and the operator

ultimately requested that their pre-existing broiler be returned in place of the lidded broiler.

The operator did not request that the pulley be adjusted back to its original settings for the

old broiler. This suggested that the original broiler may have had plume containment

problems prior to this study.

Properly-designed ventilation systems should be able to capture and contain all of the

effluent at the design airflow. The DCKV system is designed to reduce fan speed during low

load conditions for a properly designed ventilation system. If a ventilation system is

undersized in the first place, DCKV adjustments will not improve plume capture and

containment.

49


LIDDED BROILER SHOWCASE

The lidded broiler showcase was held at the FSTC on Monday, October 20th, 2014. Fourteen

people attended the event, including facilities managers, restaurateurs, and foodservice

consultants, as well as representatives from the utilities, community organizations, and a

variety of industries—including grocery and food recycling services. The seminar included an

overview of the lidded broiler and estimated annual savings from each of the four field sites.

This showcase functioned as a training demonstration for the field sales team.

Photo Credit: FNI

FIGURE 52. LIDDED BROILER DEMONSTRATION AT THE 10/20/2014 SHOWCASE AT FSTC

The showcase featured a live demonstration by Sideboard—one of the sites that participated

in the study. One of Sideboard’s line cooks, who was well-trained on lidded broiler

operations, gave the demonstration (Figure 52) and highlighted best practices for how the

units were used. Food was cooked to order at first, then batch-cooked to show the

temperature uniformity when cooking heavy loads. It was a great opportunity to recreate

the cooking space of a site that had been using the broiler in a production environment

using the restaurant’s menu items.

Video monitors at each end of the room continuously ran a slideshow of the four case

studies, highlighting the differences in energy use between the standard and lidded broilers

at each site, as well as the estimated cost savings. FSTC staff was available to answer

questions and to give lab tours. PG&E customer representatives sat down with attendees to

review their accounts, using PG&E’s My Energy website to discuss their energy use and

strategies to save energy and costs.

The showcase successfully provided the attending representatives with useful information

on the lidded broiled technology. The real-world data and real-time cooking demonstrations

generated a strong interest in the lidded broiler’s cooking performance, as well as its

potential for saving energy in restaurants.

50


CUSTOMER FEEDBACK SURVEY

Operators at the four sites where a standard broiler was replaced with a lidded char-broiler

with infrared burners and thermostatic controls were administered a set of surveys that

assessed operating patterns, as well as expectations and concerns about lidded broilers

when the operators first participated in the study. A follow-up survey evaluated the level of

satisfaction with the lidded char-broilers once they were replaced, and provided owner

feedback on the level of energy savings needed to provide an incentive for purchase. Three

of the four sites responded to the survey. The survey results can be found in Appendix 2.

PURCHASING INFLUENCES In general, survey respondents conducted their own research when purchasing appliances,

relying on retailers and kitchen designers for additional support. Many, though not all of the

pre-existing equipment was purchased new (one standard broiler was provided by the FSTC

for the purposes of this study). Cost and ease of maintenance were the top-rated factors

influencing their decision to purchase a new char-broiler, followed closely by a unit’s

condition and reputation for durability, energy-efficiency, the terms of the broiler’s

warranty, and the overall strength of the manufacturer’s brand.

SITE OPERATING PRACTICES Owners who participated in the study had a mixed record of operating practices when using

their pre-existing broilers. Some sites ran all burners at full-power. Other sites—particularly

those cooking a variety of food products simultaneously—ran their broiler in mixed mode

(with all burners on full-power on one side, and reduced power—usually 75%—on the

other). Char-broiler service and maintenance at the sites was similarly mixed. Some sites

performed regular internal maintenance to optimize broiler performance, others serviced

their broilers (such as changing out valves) only when the broiler was not functioning

properly.

The most common items cooked on the char-broiler among the survey respondents were

burgers and chicken. Batch cooking on the char-broiler was common among the

respondents, though not universal. At some sites, the broiler was were used solely for either

a-la-carte cooking at some sites; At other sites the broiler was used only used for

generating sear marks (finishing with a different cooking method). At the Growler, for

example, certain menu items would be seared on broiler, and finished in their smoker.

LIDDED CHAR-BROILER FEEDBACK Some of the concerns that respondents initially expressed about replacing their existing

char-broiler included the possibility that the thermostatically-controlled broiler would not

cook at the expected rate (because the burners would shut off at the thermostat setpoint).

Safety—specifically the potential for operator burns when closing the lid—was also an initial

concern, as was the cleaning and maintenance of the hooded area. One respondent

expressed concerns about the durability of the electrical components under the char-

broiler’s high temperatures.

Many of these concerns were addressed over the course of this study. As users saw the

lidded broiler successfully installed and operated in their production environment, and as

51


operators were guided by FSTC staff through how to safely operate the broiler to maximize

productivity at their site, many of the concerns were eventually alleviated. One respondent

noted that there was no decline in productivity; that the lidded broiler performed as well as,

if not better than, the pre-existing broiler. However, some of these initial concerns were

also identified later as feedback after the replacement lidded broilers were installed. This

included feedback on longer cook times as well as on broiler cleaning; The additional surface

area of the lid resulted in more cleaning time for operators.. For some respondents, getting

the staff to cook with the lid down was a challenge—particularly for line items. Operators

sometimes forgot that the food was in the broiler when cooking with the lid down, and as a

result tended to overcook food if not properly trained, due to the lidded broiler’s efficiency.

First cost remained a concern at one site—a concern that would influence the decision to

purchase a lidded broiler. But the same site also noted that, while price may be a factor, as

staff continues to be educated on energy-efficiency, that they would be more inclined to

spend more on efficient equipment as a result of the savings.

Despite these concerns, respondents were generally positive on the overall performance of

the lidded broiler. On a scale of one to five, with five being the highest, the post-installation

survey indicated an overall high level of satisfaction with the replacement lidded char-broiler

in meeting operator’s production needs (4.67). Survey respondents also rated the lidded

char-broiler high on its ease of configuration and use (5.00). Owners who saw a significant

difference in their billing data as a result of the lidded char-broiler rated it high (4.00).

However, not all respondents were able to make the assessment; Sideboard removed the

lidded broiler shortly after installation due to the smoke plume spilling over their hood, so

there was not enough time to see any reduction in broiler energy use at that site.

Other specific recommendations from operators on the lidded broiler design included a

redesign of the lid to allow more smoke to exit the rear, a thermostat with two zones for lid-

down cooking when cooking multiple types of food product, and integrating a timer into the

broiler for operators to use when cooking with the lid down in order to avoid overcooking.

For future lidded broiler designs, manufactures are encouraged to consider these design

comments, and issues reported from operators.

Education on lidded broiler cooking techniques was cited as the primary tool to minimize

many barriers to optimizing cooking performance, food quality, and energy use. Sideboard,

for instance, noted that operators rarely or never closed the lid on the char broiler when it

was initially replaced (closing it during cooking only if there were one or two items to load).

After training on broiler use, the same operators began closing the lid almost 50% of the

time during cooking and almost 100% the time during idle. Sites also demonstrated several

best practices as a result of training on its unique features; At The Growler, a common

practice after broiler replacement, training, and extended use was to bring the lidded broiler

up to temperature with the lid open. When the broiler was at the desired temperature (often

above the thermostat setpoint) the food was loaded to get the proper marking, and the lid

then closed to finish at the thermostat setpoint. When asked what expected annual savings

would be needed to justify the purchase of a lidded char-broiler, $1,000 was proposed, or

roughly the first year of average expected annual savings in this study. It was also noted

that the ease of the rebate process was as important as the amount, suggesting that a

more upstream incentive approach may be needed to ensure widespread adoption in this

market.

52


CONCLUSIONS AND RECOMMENDATIONS

Using lidded broilers with IR burners and thermostatic controls can dramatically increase

production capacity and cooking-energy efficiency —particularly when cooking with the lid

down. While many traditional restaurant operators will be reluctant to cook with the lid

down, the technique has the potential to increase cooking-energy efficiency by 18%. The

biggest energy savings with a lidded broiler, however, are from reduced idle energy rates

when the lid is down and the thermostat engaged. The site study proved that unless the lid

is closed, the lidded broiler will not result in energy savings because it will operate like a

conventional, non-thermostatically-controlled broiler. Unless the thermostat is set at a very

low temperature, the burners may still cycle during lid-up operation.

There was generally a high level of satisfaction with the broiler; Operators noted improved

cooking performance, thanks to the relative temperature uniformity of the lidded broiler’s

infrared burners. Full field analysis results can be seen below in Table 6. By utilizing the lid,

appreciable energy savings were achieved at all four restaurant locations—a 30% decrease

in energy use on average. Figure 52 illustrates the daily energy use at each site before and

after replacement. An average of about two and a half therms was saved per site. The

results for the Growler in particular, which reduced the energy use of its broiler by 54%,

demonstrate the promise of this new technology. For the two sites where behavioral change

training was implemented, an additional 14% energy savings was realized.

TABLE 6. RESTAURANT NAME, LOCATION, AND UPGRADED BROILER

RESTAURANT EXISTING

BROILER

AVERAGE

DAILY

ENERGY

USE

(THERMS)

CHANGES IN AVERAGE DAILY

ENERGY USE WITH

REPLACEMENT BROILER

(THERMS)

ENDING

AVERAGE

DAILY ENERGY

CONSUMPTION

(THERMS)

ANNUAL

OPERATING

COST

SAVINGS*

(%)

CHANGE DUE

TO

REPLACEMENT

ONLY (%)

ADDITIONAL

CHANGE DUE

TO TRAINING

(%)

Norm’s Place 9.59 -2.08 (22%) N/A 7.51 $757 (22%)

The Growler 6.56 -2.94 (45%) -0.57 (16%) 3.05 $1,278 (54%)

Sideboard 10.67 -0.73 (7%) -1.14 (11%) 8.80 $681 (18%)

Esin 10.73 -2.75 (26%) N/A 7.98 $1,001 (26%)

*Calculation for annual savings based on $1.00 per therm

Source: FNI

53


Source: FNI

FIGURE 53. DAILY ENERGY USE BEFORE AND AFTER BROILER REPLACEMENT

While these studies may have illustrated the clear benefits of switching to lidded,

thermostatically-controlled broilers, they have also highlighted target areas for

improvement. One clear example of this is the effluent spillover that occurred at Esin. Given

the current lidded broiler design, the smoke plume was shifted forward, hampering the

ventilation of its effluent at that site. In the case of Esin, this shift was significant enough to

allow the effluent to escape and fill the kitchen during particularly high volume cooking.

Though this plume alteration was relatively minor, this rendered the broiler unfit for use,

given the current infrastructure of the restaurant’s ventilation. Thus, while lidded broiler

technology can generate significant energy savings, proper ventilation hood sizing and other

similar kitchen conditions must be considered to make the most of this emerging

technology.

As evidenced by the results at Sideboard, it is also clear that education and training of

kitchen staff on the optimal operation of lidded, thermostatically-controlled broilers is

essential to achieve a maximum energy savings. All kitchen staff involved in operating the

broiler should be educated in the optimal thermostat setting and burner knob modulation for

the restaurant’s needs. This means talking directly with all broiler operators, rather than

just the manager. Using data while explaining the potential savings associated with these

energy-saving practices was also particularly effective in spurring adoption.

In the case of Sideboard, behavioral changes resulting from training on the lidded broiler

more than doubled energy savings at the restaurant. Further monitoring that would include

operator practices when using lidded, thermostatically-controlled underfired broilers may

prove that the technology could generate even greater savings than is quantified in this

study. Based on the results found at Sideboard and The Growler, restaurants have the

potential to reduce broiler energy use by an additional 30% through behavior modification.

This means that restaurants can average about 40% energy savings by both switching to a

lidded broiler and making behavioral modifications. Best-practices on lidded broiler

operations could be adopted by manufacturers both in their literature, and by educating

their distributors and representatives in order to enable them to guide end-users at the

0

2

4

6

8

10

12

Norm's Place The Growler Sideboard Esin

Dai

ly H

ou

rs o

f O

pe

rati

on

Restaurant

Pre-Replacement

Post-Replacement

54


point-of sale on how best to use their lidded broiler.

The energy savings from lidded broilers are already significant enough to warrant serious

consideration, but further improvements are always possible. Other potential energy-saving

enhancements that have yet to be explored would be automatic pilot ignition systems, split

broiler lids, better lid insulation, and the use of demand response ventilation systems. A

two-stage gas valve, controlled by lid position, may be an alternative to the thermostat and

could also be researched. Additionally, an altered lid design for improved effluent capture

and containment could help solve ventilation difficulties. In terms of behavioral changes,

implementation of closed-lid cooking should also prove to be valuable. Combined with

education and training of kitchen staff on other aspects of the optimal operation of lidded,

thermostatically-controlled broilers, these changes should contribute to even greater

potential energy savings.

Overall, there is great potential savings with the lidded broiler, especially in restaurants that

leave their units idling for long periods. For widespread market adoption, the lidded broiler

concept will need to be refined and promoted by the manufacturers. Once the industry and

the end-users become aware of the large potential savings of the lidded broiler, more

manufacturers will begin adopting and improving the technology. Further market adoption

will also spur cost reductions, thanks to increased sales volume to offset the initial R&D

costs already invested into the technology. In the current market, the cost of steel is the

primary driver of broiler price. Given that lidded broilers use only an estimated 20%-30%

more steel than conventional broilers, it is clear that the current lidded broiler price (almost

three times that of the conventional broiler) has significant room for reduction. However, to

drive early adoption sales and ultimately drop the price point down to where it should be,

initial market stimulation is needed.

The savings realized by lidded broilers makes it a viable early-replacement candidate. With

cost savings between $750 and $1,000 at the sites studied, operators could realize a four

year or less simple payback period based on the broiler’s current $3,800 purchase price. A

rebate equivalent to the first year of savings could reduce this payback period to under

three years—further enhancing the potential for its increased adoption in the marketplace.

With the merits of this maturing new technology now validated, further investigation should

be made into quantifying the benefits of specific features. For example, studies could be

done on unlidded broilers with IR burners or lidded broilers with atmospheric burners and

radiant plates. By isolating the different features of the advanced broiler investigated in this

study, insight could be gained on the contribution of each individual feature towards energy

savings. Through this type of investigation, lidded broiler technology could be further

refined, for combined energy and cost effectiveness.

A-1


APPENDIX 1: APPLIANCE SPECIFICATIONS

Royal RIBT-36

A-2


APPENDIX 2: SURVEY RESULTS

ESIN PRE-MONITORING SURVEY

A-3


APPENDIX 2: SURVEY RESULTS (CONTINUED)

Esin Pre-monitoring Survey, Page 2

A-4



ESIN POST-MONITORING SURVEY

A-5



Esin Post-monitoring Survey, Page 2

A-6



Esin Post-monitoring Survey, Page 3

A-7



GROWLER PRE-MONITORING SURVEY

A-8



Growler Pre-monitoring Survey, Page 2

A-9



GROWLER POST-MONITORING SURVEY

A-10



Growler Post-monitoring Survey, Page 2

A-11



Growler Post-monitoring Survey, Page 3

A-12



SIDEBOARD PRE-MONITORING SURVEY

A-13



Sideboard Pre-monitoring Survey, Page 2

A-14



SIDEBOARD POST-MONITORING SURVEY

A-15



Sideboard Post-monitoring Survey, Page 2

A-16



Sideboard Post-monitoring Survey, Page 3

A-17


APPENDIX 3: “CASE STUDIES IN ENERGY-EFFICIENT LIDDED

CHAR-BROILERS” SHOWCASE (10/20/14)

A-18



CHAR-BROILERS” SHOWCASE (10/20/14)—CONTINUED

A-19




A-20




A-21


REFERENCES

Johnson, Frank. Fisher, Don. Brand, Larry. Heustis, Eddie (July 2013). Advanced

Foodservice Appliances for California Restaurants. Commission Contract No. #500-2014-

021.

Owen, Mark (2013). ASHRAE Handbook of Fundamentals. Atlanta, GA:ASHRAE.

Zabrowski, David. Mills, Lauren (April 2010), Characterizing the Energy Efficiency Potential

of Gas-Fired Commercial Foodservice Equipment. Commission Contract No. #500-06-028.

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