SURVEY OF RTU FAN EFFICIENCY AND OPERATION ... & Engineering Services FIELD SURVEY OF RTU FAN...

Design & Engineering Services

FIELD SURVEY OF RTU FAN EFFICIENCY AND

OPERATION PATTERNS

HT.11.SCE.020 Report

Prepared by:

Design & Engineering Services

Customer Service Business Unit

Southern California Edison

December 2012

Field Survey of RTU Fan Efficiency and Operation Patterns HT.11.SCE.020

Southern California Edison Page i Design & Engineering Services December 2012

Acknowledgements

Southern California Edison’s Design & Engineering Services (DES) group is responsible for

this project. It was developed as part of Southern California Edison’s HVAC Technologies

and Systems Diagnostics Advocacy Program (HTSDA) under internal project number

HT.11.SCE.020. Jay Madden, P.E. conducted this technology evaluation with overall

guidance and management from Jerine Ahmed. Western Cooling Efficiency Center (WCEC)

and Davis Energy Group (DEG) designed and conducted the field surveys, tabulated the

data, and prepared the report for this project. For more information on this project, contact

[email protected].

Disclaimer

This report was prepared by Southern California Edison (SCE) and funded by California

utility customers under the auspices of the California Public Utilities Commission.

Reproduction or distribution of the whole or any part of the contents of this document

without the express written permission of SCE is prohibited. This work was performed with

reasonable care and in accordance with professional standards. However, neither SCE nor

any entity performing the work pursuant to SCE’s authority make any warranty or

representation, expressed or implied, with regard to this report, the merchantability or

fitness for a particular purpose of the results of the work, or any analyses, or conclusions

contained in this report. The results reflected in the work are generally representative of

operating conditions; however, the results in any other situation may vary depending upon

particular operating conditions.


Southern California Edison Page ii Design & Engineering Services December 2012

EXECUTIVE SUMMARY

This study focuses on small commercial rooftop unit (RTU) supply air fans and how the

thermostats controlling these supply fans are configured. According to the 2006 California

Commercial End Use Survey, supply fans in the more than one million RTUs in California

contribute 11.9% of total statewide commercial building electrical consumption. This

compares to the cooling component (compressor and condenser fan) which represents

14.9% of total statewide electrical consumption. From this context, addressing supply fan

energy efficiency is an important future research area. To evaluate the energy savings

potential of any potential supply fan efficiency opportunity, the baseline operating

characteristics need to be quantified based on actual field conditions.

The goal of this project was to field survey small commercial building establishments to

assess in-situ RTU supply fan electrical demand, and to record how the thermostat

controlling the RTU is programmed, if at all. In addition to defining occupied and unoccupied

periods of the day/week, a review of the thermostat configuration allows one to document

whether the supply fans are operating continuously or cycling in response to a thermostat

call for cooling or heating.

Field surveys were completed during summer 2012 at 216 RTUs in northern and southern

California, with rooftop field measurements of supply fan power at a subset of 58 RTUs.

Complete data sets were not obtained for every RTU surveyed as the access provided by

each of the 98 surveyed commercial sites varied, resulting in different pieces of data

recorded at each site. This is why many of the analyses have data set populations less than

the full 216 records. The survey team gained access to commercial establishments by

coordinating with HVAC contractor service calls, coordinating with building owners and

municipal/public entities, and by cold-calling commercial establishments. Nameplate RTU

data were collected at the 58 units, allowing RTU supply fan power characterization in terms

of a kW/nominal ton metric.

The survey results indicated that the supply fans ran continuously at about 40% of the

surveyed RTUs serving commercial buildings. The other 60% cycled with calls for cooling or

heating. In a third of the surveyed units, the supply fan operated continuously during

unoccupied hours, with another 36% of the fans cycling during unoccupied hours. Table 1

summarizes these results. While these proportions varied by building type, the sample sizes

for each building type were not sufficiently large to make conclusions that are more

detailed.


Southern California Edison Page iii Design & Engineering Services December 2012

TABLE 1: FAN OPERATION PATTERNS FOR OCCUPIED AND UNOCCUPIED STATES

ROOFTOP UNITS (N=193)

FAN OPERATION PATTERN OCCUPIED UNOCCUPIED

Continuous 39.4% 32.1%

Cycles 58.5% 36.3%

Off 0.0 29.5%

Unknown 2.1% 2.1%

Measured supply fan power in this survey as presented in Table 2 was slightly lower than

results from the datasets in the Bonneville Power Administration RTU Pilot Servicing

Program and the California Energy Commission (CEC) Small HVAC System Design Guide.

Direct-drive supply fans were found to consume less energy per nominal ton of capacity

relative to belt-drive fans. However, direct-drive fans were not observed in RTUs above 5

tons nominal capacity.

TABLE 2: COMPARISON OF MONITORED SUPPLY FAN POWER DENSITY

STUDY FAN POWER DENSITY (KW/NOMINAL TON)

SCE Survey 0.15

Bonneville Power Administration RTU Pilot Servicing Program 0.18

CEC Small HVAC System Design Guide 0.18

Based upon the survey observations, RTU potential supply fan energy efficiency measures

should not assume continuous supply fan operation during occupied hours. This assumption

would result in calculated energy savings higher than actual results. It is also difficult to

draw a conclusion regarding fan energy savings during unoccupied hours. One-third of the

RTUs were observed to be operating continuously at night, some of which could possibly be

due to thermostat programming errors. Theoretically, the programming errors should be

corrected before fan energy measures are applied to these buildings.

The survey found programmable thermostats or EMS at a majority of the RTUs, which

provides the opportunity for features like programmed operation and night setback

operation. However, lack of understanding of these controls resulted in bypassing these

opportunities. Better awareness could result in better comfort levels in the conditioned

spaces as well as lower energy consumption.


Southern California Edison Page iv Design & Engineering Services December 2012

ACRONYMS

AC Air Conditioning Unit

ACM Alternative Calculations Method

ASHRAE American Society for Heating Refrigeration and Air Conditioning

BPA Bonneville Power Administration

CA California

CEUS California Commercial End-Use Survey

CFM Cubic Feet per Minute

DEG Davis Energy Group

DOE Department of Energy

EMS Energy Management System

HVAC Heating, Ventilation, and Air Conditioning

IAQ Indoor Air Quality

kW kiloWatt

PNW Pacific Northwest

RTU Rooftop Unit

RTUG Regional Rooftop Working Group

SCE Southern California Edison

UC University of California

WCEC Western Cooling Efficiency Center


Southern California Edison Page v Design & Engineering Services December 2012

CONTENTS

EXECUTIVE SUMMARY ________________________________________________ II

INTRODUCTION ____________________________________________________ 1

BACKGROUND ____________________________________________________ 2

Ventilation Code Requirements ................................................. 2

Bonneville Power Administration RTU Pilot Servicing Program ....... 3

California Commercial End-Use Survey (CEUS) ........................... 8

Small HVAC System Design Guide ........................................... 10

METHODOLOGY __________________________________________________ 11

Survey Protocol..................................................................... 11

Survey Schedule ................................................................... 12

RESULTS_________________________________________________________ 13

DISCUSSION _____________________________________________________ 28

CONCLUSIONS ___________________________________________________ 30

REFERENCES _____________________________________________________ 31

APPENDIX A: SURVEY DATA COLLECTION FORM _________________________ 32

APPENDIX B: SURVEY DATA BY SITE ___________________________________ 35


Southern California Edison Page vi Design & Engineering Services December 2012

FIGURES

Figure 1: RTU evaporator fan kW per ton (BPA study) ...................... 4

Figure 2: Capacity of Surveyed RTUs ............................................. 5

Figure 3: RTU Fan Hours per Day .................................................. 6

Figure 4: Compressor runtime vs. fan runtime ................................ 8

Figure 5: Survey sites by county ................................................. 14

Figure 6: Survey sites by facility type and county .......................... 15

Figure 7: Number of RTU “in building” surveys by facility type and

region ....................................................................... 15

Figure 8: Number of RTUs per site by region (N or S) and facility

type (individual site values shown in black) .................. 16

Figure 9: Observed RTU nameplate nominal capacity ..................... 17

Figure 10: Thermostat manufacturers by facility type .................... 18

Figure 11: RTU manufacturers by facility type ............................... 18

Figure 12: Fan operation characteristics during occupancy by

region and facility type ............................................... 20

Figure 13: Fan operation characteristics during non-occupied

periods by region and facility type ................................ 20

Figure 14: Hours of continuous fan operation by facility type .......... 21

Figure 15: The average number of business hours per business

day by facility type ..................................................... 22

Figure 16: Ratio of average daily available cooling hours to

business occupancy hours ........................................... 23

Figure 17: Measured supply fan kw/ton by site ............................. 24

Figure 18: Fan power per ton by drive type versus RTU tonnage ..... 24

Figure 19: Measured supply fan kw/ton by region and facility type .. 26

Figure 20: Individual site occupied thermostat setpoints (by

region-facility-schedule type)....................................... 27

Figure 21: Individual site unoccupied thermostat setpoints in black

(by region-facility-schedule type) ................................. 27


Southern California Edison Page vii Design & Engineering Services December 2012

TABLES

Table 1: Fan operation patterns for occupied and unoccupied

states ........................................................................ iii

Table 2: Comparison of monitored supply fan power density ............ iii

Table 3: RTU fan categorization sorting rules .................................. 7

Table 4: Comparison of fan operation in multiple studies .................. 9

Table 5: Thermostat operation ( CEUS study) ................................. 9

Table 6: Types of programmed RTU operation .............................. 13

Table 7: Characterization of fan operations in terms of occupancy

state, system setting, and fan setting ........................... 19

Table 8: Fan operation patterns for occupied and unoccupied

states ....................................................................... 19

Table 9: Average fan power per ton by drive type and RTU

tonnage .................................................................... 25

Table 10: Supply Fan Power Density ............................................ 28


Southern California Edison Page 1

Design & Engineering Services December 2012

INTRODUCTION

This study focuses on small commercial rooftop unit (RTU) supply air fans and how the

thermostats controlling these supply fans are configured. The information in this study

assists in understanding the actual energy consumption and savings potential of

conservation strategies that reduce supply fan energy and/or reduce fan operating hours.

To evaluate the energy savings potential of any technology, the baseline operating

characteristics of the device or system need to be quantified, documented, and based on

actual performance. One often overlooked energy consuming component in commercial

buildings is the supply air fan found in the ubiquitous commercial rooftop unit (RTU). From a

statewide perspective, the operation of RTU supply air fans is of particular interest because

the more than one million RTUs in California contribute to associated annual ventilation

energy use totaling 11.9% of statewide commercial building electrical consumption. This

compares to the cooling (compressor and condenser fan) annual energy end use estimate of

14.9% [1]. Supply fan annual energy use is dependent upon average operating hours,

which varies widely depending on the facility type, space conditioning loads, comfort

preferences, and how the RTU fan is controlled.

Although both the RTU compressor(s) and supply fan are controlled by the same

thermostat, the thermostat can operate the supply fan independently. The thermostat is set

to one of the following settings:

“Auto” where the supply fan cycles with the compressor operator

“On” where the fan operates regardless of compressor operation

Programmable thermostats and energy management systems (EMS) may be programmed

to operate the fan on a schedule, such as during occupied hours only, to meet building

ventilation needs. Therefore, surveying thermostat settings is required to gain

understanding of typical operation patterns of RTU supply air fans.




BACKGROUND

By law, mechanical ventilation is required in all buildings, but a significant percentage of

buildings that rely on RTU supply fans for ventilation do not program the fan to provide

ventilation during all occupied hours. As a result, ventilation is only provided when the fan is

running to satisfy a thermostat call for heating or cooling. Conversely, some fans operate

continuously even in unoccupied buildings. Additionally, the average fan power consumed in

RTUs is impacted by the fan design and the resistance of its ductwork.

It is difficult for a utility program to estimate the energy savings for fan efficiency or fan

controls when the baseline run-time and power consumption is unknown. Southern

California Edison (SCE) and Western Cooling Efficiency Center (WCEC) searched for existing

literature for commercial buildings with which to evaluate and compare supply fan

operation, supply fan power consumption, or both.

VENTILATION CODE REQUIREMENTS

Ventilation design in commercial applications is code-driven and regulated to balance

the competing goals of maintaining improved air quality with building energy

consumption.

California’s most recent Building Energy Efficiency Standards (2008) states that

occupied spaces in new buildings must be ventilated mechanically one hour before

occupancy and during all periods in which the space is usually occupied, with the rate

of ventilation varying by use and occupant density [2]. This requirement dates back

to California’s first version of the Building Energy Efficiency Standards published in

1978 [3], which based requirements on the American Society for Heating

Refrigeration and Air Conditioning (ASHRAE) standard 62-73. Regulations in other

states vary but most, if not all, are based on the International Code Council’s

International Mechanical Code, which is based on ASHRAE’s current version of the

ventilation standard 62.1, which requires mechanical ventilation in occupied

commercial buildings.




BONNEVILLE POWER ADMINISTRATION RTU PILOT SERVICING

PROGRAM

The Bonneville Power Administration (BPA) is the federal marketing agent for power

to all of the federally owned hydroelectric projects in the Pacific Northwest. The

Pacific Northwest (PNW) Regional Technical Forum, through the Regional Rooftop

Working Group (RTUG), surveyed and monitored approximately 150 RTUs in the

greater Seattle area during the summers of 2009 and 2010. Survey data compiled

from this literature review included RTU cooling capacity (tons), evaporator fan kW,

thermostat settings, and thermostat schedules. The RTUG measured and logged RTU

power consumption for at least two weeks before intervention by a servicing

program. Power data were reported as average power in hourly increments. A

summary sheet and raw power data for each RTU are available on the Internet [4].

It is important to note that the BPA data comes from the greater Seattle area, where

ventilation requirements are similar to California’s Title 24 regulations for building

standards. For example, in Seattle, ventilation is currently required for all occupied

spaces, but only during the actual operating hours, not one hour proceeding

occupancy, as in the California code.

The BPA measured and analyzed evaporator fan power measured on 122 units, as

reported on the summary sheet [4]. The service technician measured and reported

the fan power when installing the monitoring equipment and again after performing

the service on the unit. To be included in this data set, the fan power reading on the

first visit had to match the fan power reading on the second visit to within 10%

(three data points failed this criterion). The remaining 119 data points were binned

by fan power per nominal ton (Figure 1). The population mean is estimated as

0.185±0.011 kW/ton with 95% confidence. The following factors affect the fan

power:

Resistance of ductwork in the distribution system

Resistance of air filters

Fan and motor efficiency

Supply air flow rates

The Air-Conditioning, Heating, and Refrigeration Institute’s Standard 340/360-2007

[5] specifies that, based on nominal tonnage, the calculated fan power should be 365

W per 1000 CFM [226 W/m3/s] of indoor air circulated for both heating and cooling.

At a typical supply fan flow rate of 400 cfm per nominal ton, this is equivalent to

0.15 kW/ton. On average, the surveyed RTU fan power (0.185 kW) consumption is

27% higher than the modeling assumption of 0.15 kW/ton at 400 cfm/ton. This is

due to higher airflow rates, greater resistance, or reduced fan/motor efficiencies.




FIGURE 1: RTU EVAPORATOR FAN KW PER TON (BPA STUDY)

The most commonly surveyed unit in the BPA study are the 5-ton RTU, followed by

7.5 ton capacity RTUs, as shown in the “8” bin in Figure 2. Eighty percent of units

surveyed were 10 ton capacity or less with no correlation between fan power per ton

and unit size.

0%

5%

10%

15%

20%

25%

0.02 0.06 0.1 0.14 0.18 0.22 0.26 0.3 0.34 0.38 0.42 0.46 0.5

Per

cen

t of S

amp

le

Measured Evaporator Fan kW per Ton of Rated Cooling

Population mean = 0.185 ± 0.011 kW/ton (95% Confidence)Sample size n=119




FIGURE 2: CAPACITY OF SURVEYED RTUS

An analysis of the BPA monitoring data from 136 RTUs determined the average

number of fan run-hours per day, and whether the fan operated continuously,

continuously during occupied hours only, or cycled with the compressor. The fan was

considered “on” when the average power over a one hour monitoring logging interval

was observed to be 20-120% of the technician measured fan power. The compressor

was considered to be “on” when the total unit power rose above 120% of the fan

only power. This approach will overestimate fan hours, since some short air

conditioner cycling intervals will be included in the 20-120% category and be

counted as the fan running for an entire hour.

Since the service technician changed the operating pattern of the fan for

approximately 10% of the units, only the data used before servicing is included in

the results. Figure 3 shows that the fan operated continuously to provide ventilation

approximately 40% of the time. An analysis of the power data estimated the fan and

compressor run-times, and the average fan and compressor run-hours per day for

each bin is shown above each bar in Figure 3. For fan run-hours of 20 hours per day

or less, fan run-time increases as the average cooling run-time increases.

0%

5%

10%

15%

20%

25%

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Per

cen

t of S

amp

le

Rated Tonnage for RTUs Surveyed

Population mean = 7.94 ± 0.82 tons (95% Confidence)Sample size n=119




FIGURE 3: RTU FAN HOURS PER DAY

The type of controller for the RTU was recorded for 107 of the RTUs surveyed. The

thermostat was a programmable thermostat 73% of the time and an energy

management system (EMS) 27% of the time. The study reported no manual

thermostats. Setbacks of cooling and heating setpoints were generally reported

during unoccupied hours.

An initial method was developed to categorize RTU fan operation as shown below:

The fan is “continuous” if it runs 24 hours a day.

The fan is “occupied” if it runs during occupied hours only.

The fan is “cycling” if the fan only runs when there is a call for heating or cooling.

The RTUs are categorized by evaluating the power draw of the RTU over the course

of a week. This method was subjective, error-prone, and time consuming, so the

following rules were developed to sort each RTU into the appropriate category as

shown in Table 3:

The fan is “continuous” if the fan is running 90% of the time.

The fan is “occupied” if the compressor run time percentage divided by the fan

time percentage is less than 0.75 and the fan runs less than 90% of the time.

The fan is “cycling” if the compressor run time percentage divided by the fan time

is at least 0.75 and the fan runs less than 90% of the time.

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

0-4 4-8 8-12 12-16 16-20 20-24

Per

cen

t of S

amp

le

Fan Run Hours Per Day

Sample size n=136

Avg. fan hrs/day=10.1

Avg. comphrs/day=7.0












While 0.75 may be lower than expected, it is required to account for the difficultly in

determining the difference between fan and compressor operation in hourly averaged

data. For example, extra “fan only” hours are in many cases full RTU operation for a

partial hour. Selecting 0.75 as the cutoff between cycling and occupied-only use

resulted in the closest match to a subjective graphical analysis done previously.

Applying these parameters, 40% of the RTU fans surveyed ran continuously, 27%

operated only with the compressor when providing cooling, and 33% ran during

occupied hours regardless of the cooling state (Figure 4).

TABLE 3: RTU FAN CATEGORIZATION SORTING RULES

FAN OPERATION CATEGORY EQUATION

Continuous:

Occupied:

Cycling:




FIGURE 4: COMPRESSOR RUNTIME VS. FAN RUNTIME

CALIFORNIA COMMERCIAL END-USE SURVEY (CEUS)

The California Commercial End-Use Survey of 2003 estimates the magnitude of

electricity end-usages in commercial buildings [7]. The survey included a sample of

2,790 commercial facilities from the service areas of Pacific Gas and Electric (PG&E),

San Diego Gas & Electric (SDG&E), Southern California Edison (SCE), Southern

California Gas Company (SCG), and the Sacramento Municipal Utility District

(SMUD). The objective of the study is not specific to RTUs, but several details about

RTUs were gathered as part of the survey. Because of privacy concerns, this report is

not publicly available, so SCE provided an analysis of the survey data for their

service territory only.

The CEUS had significantly more classifications for the fan operation than did the

BPA study, and classified the fan operation during both occupied and unoccupied

hours. Table 4 shows that the sample of 568 RTUs and associated thermostats

indicate continuous operation of fans in 9.3% of units and continuous operation

during occupied hours in 44.9% of the units. The measured fan hours in the 2003

CEUS study is significantly less than measured during the 2009 BPA Rooftop Unit

Servicing Program, with the fan operating less during both occupied and unoccupied

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Co

mp

ress

or

run

tim

e [%

]

Fan Runtime [%]

cut-off

Continuous

Occupied

Cyclic




hours. The CEUS data also shows that programmable thermostats and EMS were

significantly less prevalent in 2003 as shown in Table 5.

TABLE 4: COMPARISON OF FAN OPERATION IN MULTIPLE STUDIES

Fan Operation

Pattern

BPA ROOFTOP UNIT SERVICING 2009-

10 (N=133)

CEUS 2003

(N=568)

Occupied Hours

Unoccupied

Hours Occupied Hours

Unoccupied

Hours

Continuous 73% 40% 44.9% 9.3%

Cycles 27% 60% 51.5% 31.9%

Manual 0.0 0.0 3.5% 1.6%

Off 0.0 0.0 0.0 42.8%

Night Cycles 0.0 0.0 0.0 9.3%

Unknown 0.0 0.0 0.1% 5.1%

TABLE 5: THERMOSTAT OPERATION ( CEUS STUDY)

CONTROL TYPE PERCENT OF SAMPLE (N=568)

Unknown 9.4

Always On 3.6

EMS 6.1

Manual 41.4

Programmable 31.3

Time Clock 8.1




SMALL HVAC SYSTEM DESIGN GUIDE

The Small HVAC System Design Guide, published by the CEC, evaluated several

parameters that effect RTU efficiency, including fan energy consumption [7]. The

2003 report presented average airflow and power measurements for evaporator fans

in 79 RTUs in California, a subset of the 215 total units monitored for the study. The

average measured airflow was 325 cfm/ton and the average measured fan power

was 0.18 kW/ton. This is in agreement with the BPA study from 2009, which

suggests that fan power averages are not specific to geography and did not change

between 2003 and 2009.




METHODOLOGY

The goal of this survey was to collect data relevant to supply fan operation from over 200

thermostats, with a target subset of over 50 “on-roof” data points. On-roof data includes

RTU nameplate information and fan power measurements. Various strategies were

developed to gain access to commercial buildings and their roofs. Rooftop data were more

difficult to obtain. Permission from the tenant or building owner to access the roof was

required. To disaggregate the data collection sample, the team collected data from different

types of commercial buildings in northern and southern California, including restaurants,

retail stores, small offices, medical facilities, warehouses, and schools.

A two-fold approach was undertaken to collect survey sites for the in-building thermostat

portion of the project. In southern California, the project team connected with several

commercial HVAC contractors that operate in the greater Los Angeles area. The team

briefed the contractors on the nature of the work and coordinated the site visits. One of the

HVAC contractors cooperated fully and scheduled site visits directly through the dispatch

coordinator. Each day, the dispatcher informed the field survey team about the next day’s

schedule of site visits, which allowed the field survey staff to gain access to the building or

rooftop. A key advantage in this strategy was that the field survey staff could gain access to

the building and often to the rooftop in coordination with the HVAC service technician. The

field survey team also tried this approach with a HVAC contractor in the Sacramento area,

but the level of coordination and the availability of appropriate sites resulted in limited

opportunities.

The Davis Energy Group (DEG) and the Western Cooling Efficiency Center (WCEC) used

local contacts in Davis, CA to arrange some “on-roof” surveys at a commercial office park,

City of Davis public buildings, and a city public school.

SURVEY PROTOCOL

DEG worked with WCEC and SCE to develop a Field Survey Recording form to help

the team gather the appropriate data. A copy of this form is in Appendix A. The first

page of the form provides space to enter “in building” characteristics and the second

page provides space to enter “on-roof” data.

The “in building” section of the survey focused on the following:

Characterizing the facility by commercial building type

Defining the normal occupancy period for the building for each day of the week

Documenting thermostat type and model

Reviewing thermostat programming (occupied and unoccupied schedule of

temperatures, fan scheduling)

Assessing any comfort or Indoor Air Quality (IAQ) issues with the building contact

(anecdotal information)




The “on-roof” section of the survey focused on the following:

Documenting the RTU manufacturer and model number (model number includes

nominal cooling capacity information)

Documenting the RTU physical characteristics (condenser configuration, number

of compressors, presence of economizer, refrigerant type)

Documenting supply fan data (nominal horsepower, belt or direct-drive, and

measured supply fan kW)

Manufacturer model numbers were used to research and document nominal

equipment capacities, and then added to the online survey form. Whenever possible,

photos were taken to document the building exterior, thermostat, and RTU physical

characteristics. Electrical measurements were completed using a Fluke 1735 three-

phase power logger, which is commonly used in conducting energy studies and basic

power quality logging. The accuracy of power measurement of the Fluke 1735 is

specified as 1.5% of the measured value, not including errors from the current

transducers. The current transducers were I5A/50A Clamp PQ4, for which the

accuracy varies by the measured current, with the range being 2.5% of measured

value below 2.5 amps and 0.5% of the measured value above 25 amps.

The completed surveys were uploaded to a GoogleDocs site to allow the project team

to access them.

SURVEY SCHEDULE

Field activities began in late June 2012 and continued until late September 2012.

DEG hired an engineering intern to complete most of the “in building” survey work

and some of the “on-roof” data. After an initial training period in northern California,

the intern completed site surveys in Los Angeles on July 18-31, 2012 and on

September 4-12, 2012. DEG engineering technicians also gathered “on-roof” data,

and then completed all “on-roof” power measurements. The intern and engineering

technicians worked closely with the southern California mechanical contractor to

facilitate access to the chosen sites.




RESULTS

To assess the differences between RTU and fan behaviors, the team completed surveys at

98 different sites in different climate zones and sampled 216 RTUs. Not all of RTUs were

independently controlled with their own thermostats. Some of the thermostats only

displayed the current temperature and the temperature setpoints were programmed in a

building management system. In this survey study, there were four different types of

programmed RTU operation, and the types and percentages in the sample are summarized

in Table 6.

TABLE 6: TYPES OF PROGRAMMED RTU OPERATION

PROGRAMMED RTU OPERATION TYPE PERCENT OF SAMPLE (N=212)

Programmable Thermostat 83.0%

Building Management System 9.9%

Manual 0.9%

Time-Clock 6.1%

Surveys were also completed in multiple climate zones to provide a preliminary assessment

of potential differences between RTU and fan behaviors throughout California. At a subset of

the survey sites where occupancy and thermostat data were collected, rooftop access was

also provided, allowing for collection of RTU physical data (manufacturer, model number,

number of compressors, condenser coil configuration, etc.) and measurement of the supply

fan power during operation. This section of the report summarizes the results. Full site

tabulations of the data can be found in Appendix B.

The team completed site surveys in Los Angeles, Orange, and Riverside in southern

California, and Yolo and Solano in northern California. The graphs in this section provide

basic descriptive information about the survey sites. Figure 5 shows the total number of

sites surveyed in each county.




FIGURE 5: SURVEY SITES BY COUNTY

Approximately two-thirds of the total sites in northern California are in or around Davis, CA.

Within each of these counties, seven main types of commercial buildings are used in this

study, including food/liquor, health care, office, restaurant, retail, and school. Miscellaneous

commercial sites, such as theaters and automotive repair shops, are included in the study.

Figure 6 shows 83% of the survey buildings were retail, restaurant, and office sites.

Figure 7 presents the number of “in building” surveys by building type and location. Fast

food restaurants represent close to half of the “in building” surveys; office and retail sites

represent one-third of the building types.

0

5

10

15

20

25

30

35

40

45

50

55

60

Yolo Los Angeles Orange Riverside Solano

Nu

mb

er

of

Site

s

County




FIGURE 6: SURVEY SITES BY FACILITY TYPE AND COUNTY

FIGURE 7: NUMBER OF RTU “IN BUILDING” SURVEYS BY FACILITY TYPE AND REGION

13

1

9

6

1

1

1

11

9

12

5

4

2

29

1

2

Los Angeles

Orange

Riverside

Solano

Yolo

Co

un

ty

Facility Type

0

10

20

30

40

50

60

70

80

90

Restaurant Office Retail Store Misc School Food/Liquor Health Care

Nu

mb

er

of

RTU

s

Northern CA Southern CA




Figure 8 plots the number of RTUs per site surveyed “on-roof”, by location (N=northern

CA, S=southern CA) and building type. Each black dot represents an individual data point;

the red dot and line represents the mean value and the standard error of the mean.

Interestingly, for each of the facility types, southern California sites always had more RTUs

per site than northern California. This could be an artifact of the small dataset. Nameplate

data (make and model number) collected during the “on-roof” survey were researched on

the Web to derive nominal equipment capacity (in tons).

FIGURE 8: NUMBER OF RTUS PER SITE BY REGION (N OR S) AND FACILITY TYPE (INDIVIDUAL SITE VALUES SHOWN IN BLACK)

Figure 9 provides a breakdown of observed RTU capacities. The majority of the RTUs

surveyed were found to be between four and ten tons per RTU, with capacity ranging from 3

to 25 tons. Average capacity for the 115 RTUs was 6.50 tons, with a standard deviation of

3.33 tons.

0

2

4

6

8

10

12

14

16

RTU

s/Si

te

Data Point Avg. for Facility TypeError Bars Denote One

Standard Error of the MeanN = northern CaliforniaS = southern California




FIGURE 9: OBSERVED RTU NAMEPLATE NOMINAL CAPACITY

Figure 10 and Figure 11 characterize the distribution of thermostats and RTU manufacturers

surveyed in the sample. Although Honeywell thermostats were by far the most common (63

observations), the total number of different thermostat manufacturers (22) was greater

than anticipated. In terms of RTU manufacturers, Lennox, Trane, and Carrier were the most

commonly observed (representing two-thirds of the units), with the remaining one-third

comprised of six other manufacturers.

0%

5%

10%

15%

20%

25%

30%

35%

40%

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

Pe

rce

nt o

f Sam

ple

Rated Tonnage for RTUs Surveyed




FIGURE 10: THERMOSTAT MANUFACTURERS BY FACILITY TYPE

FIGURE 11: RTU MANUFACTURERS BY FACILITY TYPE

1

1 7

10 4

1 1

2 17 31 12 1

1

11 3

15 2

2

1

2

1

1 1 2 3

1

1

2

1

1

2

9 3

1 2 4

1 4

4 5 1 13 11

1

1

8

14

2

63

1

14

17

4

1

7

2

1

2

1

1

2

12

7

5

25

1

1Source

Braeburn

Carrier

Emerson

Honeywell

Invensys

Johnson Controls

Lennox

Lux

Lux1500

LuxPro

Maple Chase

Nest

Novar

Proliphix

Ritetemp

Robert Shaw

TCS Basys Controls

Totaline

Venstar

White-Rodgers

York

Food/Liquor Health Care Misc. Office Restaurant Retail School Total

The

rmo

stat

Man

ufa

ctu

rer

Facility Type

4 2 2

2

5 3

4 10 9 2

2

1

7

6 20 1

8 3

3 3 20

1

8

2

8

26

9

27

11

26

1

American Standard

BDP

Bryant

Carrier

Goodman

Lennox

Rheem

Trane

York

Food/Liquor Health Care Misc. Office Restaurant Retail School Total

RTU

Man

ufa

ctu

rer

Facility Type




The descriptive data presented up to this point characterizes the sites, building types, RTU

characteristics, and thermostat manufacturer. To investigate the energy implications of the

supply fan and thermostat control, the data need to be evaluated from a quantitative

perspective by defining operational characteristics of the RTU supply fan based on

field-observed thermostat programming. Table 7 defines potential fan operation states

based upon whether the building is occupied or not, the thermostat is programmed or

operated manually, and whether the fan setting is “auto” or “off”. For example, continuous

fan operation can occur in either occupied or unoccupied conditions, but the thermostat

must be scheduled for operation, with the fan set in the “on” mode.

TABLE 7: CHARACTERIZATION OF FAN OPERATIONS IN TERMS OF OCCUPANCY STATE, SYSTEM SETTING, AND FAN SETTING

OCCUPANCY STATE SYSTEM SETTING FAN SETTING

FAN OPERATION OCCUPIED UNOCCUPIED SCHEDULE MANUAL AUTO ON

Continuous

Cycles

Manual – Auto

Manual – On

Off

Unknown

Similar to the results shown in Table 4: Comparison of fan operation in multiple studies

Table 4, Table 8 presents the results, for the six categories, found from the RTU survey

data. Figure 12 and Figure 13 summarize the data based on this classification for both

occupied periods of the day and unoccupied. The data are categorized by region and facility

type with the x-axis label including the total number of sites per category, and the columns

denoting the number of sites within each category. Overall, 76 out of 193 sites were found

to operate the supply fans continuously during occupancy. During non-occupied periods,

132 of 193 sites were found to have the supply fan cycling in response to cooling operation,

with none of the supply fans operating continuously.

TABLE 8: FAN OPERATION PATTERNS FOR OCCUPIED AND UNOCCUPIED STATES

ROOFTOP UNITS (N=193)

FAN OPERATION PATTERN OCCUPIED UNOCCUPIED

Continuous 39.4% 32.1%

Cycles 58.5% 36.3%

Off 0.0 29.5%

Unknown 2.1% 2.1%




FIGURE 12: FAN OPERATION CHARACTERISTICS DURING OCCUPANCY BY REGION AND FACILITY TYPE

FIGURE 13: FAN OPERATION CHARACTERISTICS DURING NON-OCCUPIED PERIODS BY REGION AND FACILITY TYPE

Figure 14 summarizes the hours of fan operation by facility type for the 76 RTUs that

operated the supply fans continuously, either with manual or scheduled thermostat control.

For manually control thermostat, the number of daily fan operating hours was determined

to be equal to the occupancy period of the day; for scheduled RTUs, the fans were assumed

to operate 24 hours per day.

23

3

16 36

21 1

106 7

6

11

23

5

2 2

53

1

291

1 3 1

9

31

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%P

erc

en

t o

f Sa

mp

le

Unknown

Manual - On

Manual - Auto

Cycles

Continuous

N = northern CaliforniaS = southern California

2 2

5 4

1

32

1

19

23

3

1636

2

1 1

106

7

6

11 23

5

31

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Pe

rce

nt

of

Sam

ple

Unknown

Cycles

Continuous

Off





FIGURE 14: HOURS OF CONTINUOUS FAN OPERATION BY FACILITY TYPE

For RTUs that do not operate the supply fans continuously, both the length of the business

day and control of the thermostat (manual control vs. programmed cooling setpoints)

dictate the number of supply fan operating hours. Figure 15 plots the average number of

business hours per business day for each of the facility types in both northern and southern

California. Many commercial buildings operate their systems both before and after normal

building occupancy times to accommodate unusual schedules, as well as to ensure that the

building is conditioned prior to occupancy.

02468

1012141618202224

Ho

urs

of

Fan

Op

era

ton

Data Point Avg. of Facility Type Error Bars Denote OneStandard Error of the Mean





FIGURE 15: THE AVERAGE NUMBER OF BUSINESS HOURS PER BUSINESS DAY BY FACILITY TYPE

The following series of graphs explore the thermostat programming in terms of variations in

cooling setpoints during occupied and unoccupied periods by facility type and location.

There are three different kinds of temperature and occupancy schedules as follows:

Manual (M): A manual cooling schedule is the result of the varying comfort

level of the business or the limitations of the thermostat, i.e.

non-programmable. When a thermostat is turned on, set, and adjusted while

the business is occupied, it is assumed that cooling is on during normal

business hours only. This assumption is made because there is no way to

determine whether business operators, with manually operated cooling,

habitually turn off or increase the temperature set-point to prevent

unnecessary cooling during unoccupied hours.

Daily (D): A daily cooling schedule is programmed in the thermostat and can

vary on an hourly basis throughout the day.

Weekly (W): A weekly cooling schedule is programmed in the thermostat

and can vary on an hourly and daily basis.

It was important to note that thermostat and cooling programs could be overridden by the

end user at any point in time, which introduced error into the analysis.

Figure 16 plots the ratio of actual conditioned hours divided by occupied hours for each of

the building types. A value of 1.0 would suggest space conditioning only occurring during

occupied periods. Values less than 1.0 represent facilities where the cooling system is only

enabled (by schedule or manually) for a fraction of the full day. Values greater than 1.0

indicate extended conditioning hours.

8

10

12

14

16

18

20

22

24

26

Ho

urs

/Day






FIGURE 16: RATIO OF AVERAGE DAILY AVAILABLE COOLING HOURS TO BUSINESS OCCUPANCY HOURS

Supply fan power readings allowed the characterization of fan energy use according to a

kW/nominal ton metric, based on the RTU nameplate data. Supply fans are either belt-drive

or direct-drive, so additional disaggregation was warranted. Figure 17 shows the range of

measured fan power per nominal ton, depending on the drive method. On average, the belt-

drive supply fans draw 0.154 kW/ton (standard error of the mean of 0.009 kW/ton) and the

direct-drive supply fans drew 0.139 kW/ton (standard error of the mean of 0.008 kW/ton).

Although the minimum power per ton measurements are close for the two drive methods,

the maximum measurements differ significantly. This difference could be due to properties

other than the motor, such as a high resistance distribution system, dirty air filters, etc.

Figure 18 plots belt-drive and direct-drive fan kW/ton, as a function of RTU capacity (tons)

and Table 9 provides similar data in a tabular form. For the sample of units surveyed, the

direct-drive fans are limited to RTUs of 5 tons or less, representing 58% of the surveyed

RTUs in the <= 5 ton size range. For both drive types, Table 9 shows almost no trend. It

appears that the fan kW/ton remains constant except for the 8.5 tonnage data. However,

given there are only two 8.5 ton belt-drive datapoints, there is no statistical basis to

indicate a trend without further data. The limited sample of larger RTUs (10 tons and

greater) also does not suggest a clear trend in the larger sized units. Due to the limited

numbers of RTU data points that have both tonnage and fan power readings, it is difficult to

determine with adequate certainty if there is a valid correlation between average fan power

per ton and RTU tonnage. Further study in this area is warranted to determine if units in the

5 to 10 size range might be preferred candidates for potential fan efficiency measure

strategies.

0

0.5

1

1.5

2

2.5

3

Rat

io

Data Point Avg. Ratio Error Bars Denote OneStandard Error of the Mean

D = Daily, M = Manual, W = Weekly

N = northern CA, S = southern CA




FIGURE 17: MEASURED SUPPLY FAN KW/TON BY SITE

FIGURE 18: FAN POWER PER TON BY DRIVE TYPE VERSUS RTU TONNAGE

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

Belt Direct

kW/t

on

Data Point Avg. for Drive Type Error Bars Denote One Standard Error of the Mean

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0 5 10 15 20 25 30

kW/t

on

Tonnage

Belt

Direct




TABLE 9: AVERAGE FAN POWER PER TON BY DRIVE TYPE AND RTU TONNAGE

BELT DIRECT

CAPACITY (TONS) COUNT AVERAGE [KW/TON] COUNT AVERAGE [KW/TON]

2.5 0 0 1 0.12

3 2 0.11 6 0.12

4 6 0.15 4 0.13

5 11 0.15 14 0.15

6 2 0.15 0 0

7.5 11 0.16 0 0

8.5 2 0.32 0 0

10 10 0.14 0 0

12.5 1 0.14 0 0

15 1 0.06 0 0

25 1 0.14 0 0

Another investigation examined the variation in fan power measurements at different

facilities and regions. The fan power per ton was categorized into the seven facility types

and then further filtered for northern and southern California. In Figure 19, individual data

points are plotted as open circles, the mean is shown with a solid red circle, and the error

bars represent the standard error of the mean. For this limited dataset, surveyed southern

California restaurant sites demonstrated a higher kW/ton than other facility types. This

observation, although anecdotal at best, is indicative for the need for further study.




FIGURE 19: MEASURED SUPPLY FAN KW/TON BY REGION AND FACILITY TYPE

The thermostat setpoints during the occupied and unoccupied periods for each facility type,

location, and thermostat type (M, D, or W) are shown in Figure 20 and Figure 21,

respectively. As seen in Figure 20, some of the designated daily and weekly schedules

appear to be inaccurate. Because these survey data were collected throughout the summer,

it is reasonable to expect that very few commercial businesses would be maintaining

setpoints during occupied periods at temperatures above 78°F, let alone 80°F1. It was

observed that of the 136 thermostat schedules, 25 may well have been programmed

incorrectly. “Incorrect” was defined as irregular temperature setpoints and schedules or

abnormally high temperature setpoints, such as a thermostat programmed with lower

cooling setpoints in the middle of the night, and higher setpoints during “normal” mid-day

occupancy periods. Many of these thermostats were operated manually, apparently

indicating that the building occupants were not able to correctly program the thermostat.

For example, if a cooling setpoint steadily decreases to 72°F, jumps to a setpoint of 80°F for

fifty minutes, and then returns to 72°F, the schedule is not programmed properly.

Conversely, in Figure 21, it is not practical for some of the businesses to cool the

conditioned space during unoccupied hours. For instance, some of the restaurants, offices,

and schools were operating their air conditioning systems to maintain temperature setpoints

below 75°F during unoccupied periods. The extreme case of cooling during unoccupied

period was one of the northern California offices that had a daily unoccupied setpoint of

1 One particular bar/restaurant establishment did have a corroborated mid-day setpoint of 80°F. They

operated numerous ceiling fans in lieu of lower cooling setpoints for much of the day. Later at night

when occupancy increased, the setpoints were lowered.

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

kW/t

on






62°F. This facility can save energy by reprogramming the thermostat or at least turning it

off while the facility is unoccupied. This may also work for other sites.

FIGURE 20: INDIVIDUAL SITE OCCUPIED THERMOSTAT SETPOINTS (BY REGION-FACILITY-SCHEDULE TYPE)

FIGURE 21: INDIVIDUAL SITE UNOCCUPIED THERMOSTAT SETPOINTS IN BLACK (BY REGION-FACILITY-SCHEDULE TYPE)

55

60

65

70

75

80

85

90

95

100

Tem

pe

ratu

re [F

]

Data Point Avg. Setpoint Error Bars Denote One Standard Error of the Mean

D = Daily, M = Manual, W = WeeklyN = northern CA, S = southern CA

55

60

65

70

75

80

85

90

95

100

Tem

pe

ratu

re [F

]

Data Point Avg. Setpoint Error Bars Denote One Standard Error of the Mean

D=Daily, M=Manual, W=Weekly

N = northern CA, S = southern CA




DISCUSSION

The survey results indicated that the supply fans ran continuously of 40% of packaged RTUs

serving commercial buildings. The other 60% cycled with calls for cooling or heating. In

one-third of the surveyed units, the supply fan operated continuously during unoccupied

hours, another 36% of the fans cycled during unoccupied hours, and the remainder of the

fans were set to off. While these proportions varied by building type, the sample sizes for

each building type were not sufficiently large to make more detailed conclusions.

Measured supply fan power in this survey was slightly lower than results from previous

studies. Table 10 compares the results of this study with those of previous works. Direct-

drive supply fans were found to have a lower demand per nominal ton than belt-drive

supply fans. However, direct-drive fans were not observed in RTUs above 5 tons nominal

capacity.

TABLE 10: SUPPLY FAN POWER DENSITY

STUDY FAN POWER DENSITY (KW/NOMINAL TON)

SCE Survey 0.15

Bonneville Power Administration RTU Pilot Servicing Program 0.18

CEC Small HVAC System Design Guide 0.18

Observations from the field survey team provide additional insights into how commercial

building owners and occupants interact with their RTU. The surveyed sites include a range

of building occupants including restaurant franchises, owner-occupied commercial sites,

tenant-occupied sites, and public buildings. The best-maintained and operated RTUs tended

to be those owned by a city, public entity, or larger organizations that have an institutional

focus on maintenance, as well as the financial allocation in the budget for regular upkeep.

Typically, the larger commercial sites need to manage and regularly schedule RTU

maintenance because of the sheer number of the systems and all the potential issues that

can arise. These larger operations also tended to control and monitor unit operation

remotely through building management systems and are therefore were better equipped to

quickly identify and fix performance problems. Among owner-occupied establishments,

there was a perceived wide range of understanding about how the RTU is controlled and

maintained. Some people were very much in tune with both the RTU and control settings,

while others were not. For the tenant-occupied establishments, the landlord or property

management company generally handles maintenance issues and the tenants often have

little knowledge about the process. The feedback from the field suggests that some

landlords seem to monitor and maintain RTUs regularly, while others only fix issues when

there are significant complaints from the employees or clientele. In the latter category,

some of the RTUs on older buildings had been repaired repeatedly to the point of being

barely serviceable.




A fair number of people interviewed on-site were not aware how the thermostats in their

establishment were set up. This was most true for tenant-occupied buildings. Examples

included verbal reporting of fan settings or cooling setpoints that didn’t match reality, e.g.

employees stating the fan is set to Auto not On, and the fan setting (on the thermostat) was

found to be set to On. Another example was one employee would state that the system is

not programmed, while a second employee stated that the system does have a program.

Despite seeing a large number of newer, programmable thermostats, most were not

programmed at all or were programmed incorrectly. In many of these cases it looked as

though someone had tried programming the thermostat but either gave up or decided to

run the system manually. Among the smaller business establishments surveyed, the

majority used their thermostats as on/off switches, turning them to Auto when they started

to feel warm (often around 12-1 PM) and then switching them to Off at the end of the

business day.




CONCLUSIONS

Survey results indicated that the supply fans ran continuously during building occupancy at

about 40% of the surveyed RTUs. The other 60% cycled with calls for cooling or heating. In

a third of the surveyed units, the supply fan also operated continuously during unoccupied

hours, with another 36% of the fans cycling during unoccupied hours. During occupied

periods, the SCE survey data is consistent with the CEUS data, with a slightly greater

weighting of supply fan cycling operation relative to continuous fan operation. During

unoccupied periods, the SCE data indicate a much greater occurrence of continuous fan

operation relative to the CEUS data (32.1% vs. 9.3%). Cycling fan operation was found in

36.3% of the surveys, which is slightly lower than the combined “cycles” and “Night cycles”

data from the CEUS study. Relative to the BPA study results, the SCE findings show much

less continuous fan operation during occupancy, and 30% “fan off” during unoccupied

periods relative to zero observed operation in the BPA study.

The measured supply fan power in the SCE survey was slightly lower than results from the

previous BPA and CEC studies. Additionally, the SCE survey results found that direct-drive

supply fans were found to have a lower demand per nominal ton than belt-drive supply

fans. This area may warrant further study.

The survey found programmable thermostats or EMS at a majority of the RTUs, which

provides the opportunity for features like programmed operation and night setback

operation. However, lack of understanding of these controls resulted in bypassing these

opportunities. Better awareness could result in better comfort levels in the conditioned

spaces as well as lower energy consumption.

Based upon the observations made during this survey, RTU supply fan energy efficiency

measures should not assume a continuous fan operation during occupied hours. This

assumption would result in calculated energy savings higher than actual results.

Calculations of fan energy savings should assume that the fan is operating when there is a

call for heating or cooling in addition to supply fan operating hours run independent of

compressor operation, which varies highly throughout the sample.




REFERENCES

[1] Itron, Inc., "California Commercial End-Use Survey," California Energy Commission, Sacramento, 2006.

[2] California Energy Commission, "2008 Building Energy Efficiency Standards," December 2008. [Online].

Available: http://www.energy.ca.gov/title24/2008publications/CEC-400-2008-003/CEC-400-2008-003-

CMF.PDF. [Accessed 21 October 2012].

[3] California Energy Commission, "Past Building Energy Efficency Standards," 26 July 1978. [Online]. Available:

http://www.energy.ca.gov/title24/standards_archive/1978_standards/CEC-400-1978-001.PDF. [Accessed 31

October 2012].

[4] Northwest Council, "BPA Rooftop Unit Pilot Servicing Program," 2010.

[5] AHRI, "http://www.ahrinet.org/," October 2011. [Online]. Available:

http://www.ahrinet.org/App_Content/ahri/files/standards%20pdfs/ANSI%20standards%20pdfs/ANSI%20AHRI

%20Standard%20340-360-2007%20with%20Addenda%201%20and%202.pdf.. [Accessed 21 October 2012].

[6] Itron, Inc., "California Commercial End-Use Survey," California Energy Commission, Sacramento, 2003.

[7] Architectural Energy Corporation, "Small HVAC System Design Guide," California Energy Commission,

Sacramento, 2003.




APPENDIX A: SURVEY DATA COLLECTION FORM




Survey Site Business Name

Survey Site ID # (DDMM-X)

Survey Site Contact Name

Survey Site Contact Phone

Facility Type (Take photo of

exterior)

Circle One: School (room), (office) or (public area);

Small office (office space), (public area);

Retail (sales area), (office);

Convenience Store;

Restaurant;

Health Care;

Warehouse;

Other (describe)

~ Age of Building & RTU Bldg RTU (estimate, if possible)

Normal Business hours (circle

days)

Open from: to: On Days: M T W R F S S



RTU Programmed Operation 24 hour, time-clock, building management system

Fan Control Mode On or Auto

Programmed Cooling Setpoint

Temperature (enter time period,

days of week, and temperature

setting during unoccupied

periods)

Temp from: to: Days: UnOcc T:

Thermostat Manufacturer (Take Photo of Thermostat)

Thermostat Model #

Any comfort or IAQ complaints?

RTU service interval (if

information available)

Select from: Only when problems; annual service; monthly

service; or _______ times per year

Photo Checklist Outside Front___ Interior Space ___ Thermostat___

Interior Exposed Ductwork ____




Assess whether site contact seems amenable to future energy efficiency projects

( Yes / No / Uncertain )

RTU Make (Photo of RTU)

RTU Model #

Refrigerant type (nameplate)

Condenser coil configuration Circle those that apply: 1 sided, 2 sided, 3 sided, 4 sided, flat

or “V”

Economizer installed? (Photo of economizer)

If yes, comment on condition Does economizer appear to be operational?

Number of compressors

Supply Fan nominal hp (nameplate)

Supply fan drive Select from: belt drive, direct drive, VFD option

Photo Checklist RTU(s)– capture condenser coil views___ Economizer___

Compressors ___ Exposed Rooftop Ductwork ____

Field Measurements

Supply fan Watts Watts or kW

Supply fan amps Amps

Supply fan voltage & phase

(single, 3)

Volts, phase




APPENDIX B: SURVEY DATA BY SITE

Appendix B.pdf

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