Learning Outcomes

Upon completion of this training one should be able to:

•Identify the influence of codes on pump & hydronic design

•Understand HVAC loads & their impact on equipment selection

•Compare hydronic HVAC system types & pipe configurations

•Determine appropriate applications for variable speed pumps

•Utilize life cycle cost economics to justify the use of variable speed pumps in both new and renovated systems

1

Overview

• Building energy use & related energy codes

• HVAC load calculations• HVAC system applications• Service hot water

applications• Economics• Specifications• Obstacles to adoption

2

Building Energy Use & Related Energy Codes

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Why Design Sustainably Conscious Buildings?In 2010, the DOE approximated that U.S. buildings accounted for:

• 41% of total energy use• 74% of electric consumption• 40% of CO2 emissions• 12% of potable water use

• By 2025, it is projected that buildingswill be the largest consumers of global energy – greater than transportation and industry combined.

http://www.eia.gov/totalenergy/data/annual/index.cfm#consumption

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Why Design Sustainably Conscious Buildings?

5

2012 Department of Energy, Building Energy Data Book

Commercial Energy End-Use

2006 U.S. Energy Information Administration (EIA) 6

Future Building Market

• Existing U.S. building stock is ~275 billion ft2

• Over next 30 years:• 52 billion ft2 will be demolished• 150 billion ft2 will be remodeled• 150 billion ft2 will be new construction

• By 2035, approximately 75% of U.S. building stock will be new or renovated

7Energy Information Administration, Courtesy of Architecture 2030

Energy Codes & Standards

International Code Series – Jurisdictions Adopt

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Energy Codes & Standards

ASHRAE Standards – Designer Reference

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Energy Codes - Commercial

ANSI/ASHRAE/IES Standard 90.1-2010

• Significant changes compared with 2007

• Continuous maintenance publishing every 3 years

• ~30% increase in building performance from 2004 version

• Consensus based document

• Cost justification required

• Only addresses energy 10

Energy Codes - Commercial

ANSI/ASHRAE/USGBC/IES Standard 189.1-2011

• Builds on ASHRAE Standard 90.1• Does not require cost justification• Addresses design & operation

‒Site Sustainability‒Water use Efficiency‒Energy Efficiency‒Indoor Environmental Quality‒Environmental Impact‒Construction & Operation

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ASHRAE Standard 189.1-2011

• Does not specifically address pumps or hydronic systems

• If criteria is not defined in ASHRAE Standard 189.1, then ASHRAE Standard 90.1 is the referenced minimum code

• Includes requirements for the measurement of energy consumption using meters

‒Enhances the potential for building audits

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Auditing

• Audit levels I, II, III defined by ASHRAE• Benchmarking – Energy Star portfolio• Meter requirement in ASHRAE Standard 189.1 or LEED

• LEED - 3 points from Performance Measurement• Push for benchmarking and auditing

‒ San Francisco‒ New York

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Energy Star Portfolio Manager

• Online energy management tool created by U.S. EPA • Tracks and assesses energy and water consumption across a portfolio of buildings

• Used by more than 200,000 commercial • Advantages to a building owner:

‒ Benchmark energy use‒ Determine energy-use intensity (kBTU/ft2) ‒ Track changes in energy and water use over ‒ Compare against national sample of similar buildings

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ASHRAE Standard 90.1-2010 Pump Applications

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ASHRAE Standard 90.1-2010 Scope• Applies to all buildings

‒ New construction‒ Additions to existing facilities‒ New & replacement equipment / components‒ Excludes residential buildings <3 stories in height

• Defines the minimum efficiency requirements

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ASHRAE Standard 90.1-2010 Structure• Multiple sections: Envelope, HVAC, Service Water Heating, Power, Lighting, & Other Equipment

• Mandatory Provisions• Prescriptive Path or Energy Cost Budget (ECB)• Appendices (Normative)

‒ A Assembly U-, C-, and F-Factor Determination‒ B Building Envelope Climate Criteria‒ C Envelope Trade-Off Methodology‒ D Climate Data

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ASHRAE Standard 90.1-2010 Section 6

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Section 6 HVAC

6.1 General

6.2 Definition of Compliance

6.4 Mandatory Provisions

6.3 SimplifiedApproach

6.5 Prescriptive

Path6.7 Submittals

Section 11 ECB

ASHRAE Standard 90.1-2010 Section 6

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Section 6 HVAC

6.1 General

6.2 Definition of Compliance

6.4 Mandatory Provisions

6.3 SimplifiedApproach

6.5 Prescriptive

Path6.7 Submittals

Section 11 ECB

ASHRAE Standard 90.1-2010 Section 6

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Section 6 HVAC

6.1 General

6.2 Definition of Compliance

6.4 Mandatory Provisions

6.3 SimplifiedApproach

6.5 Prescriptive

Path6.7 Submittals

Section 11 ECB

ASHRAE Standard 90.1-2010 Section 6

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Section 6 HVAC

6.1 General

6.2 Definition of Compliance

6.4 Mandatory Provisions

6.3 SimplifiedApproach

6.5 Prescriptive

Path6.7 Submittals

Section 11 ECB

ASHRAE Standard 90.1-2010 Mandatory• Section 6.4 Primary topics include efficiencies and controls

• Section 6.4.1 Equipment Efficiencies‒ No specified efficiencies for pumps

‒ Pump efficiencies are being developed

‒ No defined criteria for pump selection

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ASHRAE Standard 90.1-2010 Mandatory• Section 6.4.2 Calculations

‒ Design load calculations for heating and cooling

‒ Pump head calculation for the purpose of pump sizing

‒ Determined in accordance with generally accepted engineering standards and handbooks

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ASHRAE Standard 90.1-2010 Mandatory• 6.4.3 Controls

• 6.4.4 HVAC System Construction and Insulation

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ASHRAE Standard 90.1-2010 Prescriptive Path• 6.5 Prescriptive Path• 6.5.1 Economizers• 6.5.1.2 Water Economizer

‒ Required for specific OA temperature and humidity

• 6.5.1.2.2 Maximum Pressure Drop< 15’ head for pre-cooling coils and water to water heat exchanger

≥ 15’ head secondary loop required so this pressure drop is not seen by the circulating pump

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Water Cooled Chiller Piping

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Return

Supply

CoolingTower

Evaporator

Condenser

Primary Pump

Secondary Pump

CondenserPump

Head PressureControl Valve

Loads

ChillerSediment andAir Separator

Air SeparatorAnd Exp Tank

Water Cooled Chiller w/ Water Economizer

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Return

Supply

CoolingTower

Condenser

Primary Pump

Evaporator

Secondary Pump

CondenserPump

Head PressureControl Valve

Loads

Chiller

Heat ExchangerEconomizerCondenserPump

Chiller Operation

ValvePosition:Open

Sediment Separator

Air SeparatorAnd Exp Tank

Water Cooled Chiller w/ Water Economizer

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Return

Supply

CoolingTower

Condenser

Primary Pump

Evaporator

Secondary Pump

CondenserPump

Loads

Chiller

Heat ExchangerEconomizerCondenserPump

Economizer Mode

ValvePosition:Closed

Sediment Separator

Air SeparatorAnd Exp Tank

ASHRAE Standard 90.1-2010 Prescriptive Path• 6.5 Prescriptive Path• 6.5.1 Economizers• 6.5.1.2 Water Economizer

‒ Required for specific OA temperature and humidity

• 6.5.1.2.2 Maximum Pressure DropFeet of head for water to water heat exchanger< 15’ acceptable≥ 15’ head secondary loop required so this pressure drop is not seen by the circulating pump

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Water Cooled Chiller w/ Water Economizer

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Return

Supply

CoolingTower

Condenser

Primary Pump

Evaporator

Secondary Pump

CondenserPump

Loads

Chiller

Heat ExchangerEconomizerCondenserPump

Economizer Mode

ValvePosition:Closed

EconomizerChilled WaterPump

SedimentSeparator

Air SeparatorAnd Exp Tank

ASHRAE Standard 90.1-2010 Prescriptive Path• 6.5.2 Simultaneous Heating and Cooling• 6.5.2.2 Hydronic Coils

‒ Cannot cool water previously heated‒ Cannot heat water previously cooled‒ Defines change over temperature / time‒ Prohibits 3 pipe system configuration

• Common return pipe

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ASHRAE Standard 90.1-2010 Prescriptive Path• 6.5.4 Hydronic System Design & Control• 6.5.4.1 Hydronic Variable Flow System

‒ Total pump system power > 10hp & control valves designed to modulate flow based on load

‒ Design variable fluid flow - reduce pump flow rate to ≤ 50% design flow rate

‒ Control shall be based on flow or min. differential pressure

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ASHRAE Standard 90.1-2010 Prescriptive Path• 6.5.4.1 Hydronic Variable Flow System (continued)

‒ CHW pump in variable flow system > 5hp, controls are required that will result in pump motor demand of ≤ 30% of design wattage at 50% of design water flow

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Acceptable Operating Range

ASHRAE Standard 90.1-2010 Prescriptive Path• 6.5.4.2 Pump Isolation

‒ More than one Boiler/Chiller: need to be able to automatically reduce flow when a boiler or chiller is off

• 6.5.4.3 Chilled & Hot Water Temperature Reset Controls‒ Required when >300,000 BTUh system capacity unless variable flow is used to reduce pumping energy

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ASHRAE Standard 90.1-2010 Prescriptive Path• 6.5.4.4 Hydronic Heat Pump & Water Cooled AC• 6.5.4.4.2 Total pump system power > 5hp

‒ Controls to result in pump motor demand of not more than 30% of design wattage at 50% of design water flow.

‒ Based on variable speed drives

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ASHRAE Standard 90.1-2010 Prescriptive Path• 6.5.4.5 Pipe Sizing

‒ Variable flow allows smaller pipe sizes

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Pipe Sizing

• 6.5.4.5 Pipe Sizing‒ Variable flow allows smaller pipe sizes

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Pipe Sizing

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System CriteriaOperating hours: 1800 hrs/yrMax Flow: 200 GPM

Constant Flow SystemPipe size: 4” PipeHead Loss: 2.5’/100’Velocity: 5.5 fps

Variable Flow SystemPipe Size: 3” PipeHead Loss: 9’/100’Velocity: 9 fps

ASHRAE Standard 90.1-2010 Submittals• 6.7 Submittals• 6.7.2.3 System Balancing• 6.7.2.3.3 Hydronic System Balancing

‒ 1st minimize throttling losses‒ 2nd trim impeller or adjust pump speed

• except when pump ≤ 10hp or throttling loss ≤ 5% of nameplate horsepower above that required if the impeller were trimmed

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ASHRAE Standard 90.1-2010 Section 7• Section 7 – Service (domestic) Water Heating• 7.4.4.4 Circulating Pump Controls

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Building Rating / Certification

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Building Rating / Certification

Typically owner driven – NOT code•Domestic Building Rating Systems

‒ LEED‒ Energy Star‒ Building EQ‒ Green Globes

•International Building Rating System‒ BREEAM

•Pull the design market‒ progressive compared to the push of

the building codes42

Leadership in Energy and Environmental Design (LEED)™• Developed by the U.S. Green Building Council

• Rating system for buildings

• Sustainable site development

• Water savings

• Energy efficiency

• Material selection

• Indoor environmental quality

• Points / Credit System – Platinum, Gold, Silver, & Certified

• Third-party verification

• Accredited Professionals 43

Energy Star

• Developed by the U.S. Environmental Protection Agency

• Calculations are based on source energy• Label based on building energy us

• 50 indicates average energy performance• 75 or better indicates top performance

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Building Energy Quotient (bEQ)

• Developed by ASHRAE• Newest of the rating systems• Label based on building energy

use• Design performance• Operation performance• Requires an ASHRAE-certified Building Energy Assessment Professional

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Green Globes

• Developed by Energy and Environment Canada• Third-party verification• Four levels of ratings

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HVAC Load Calculations

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Building Loads

• Heating and cooling load calculations performed as required per ASHRAE Standard 90.1 Section 6 HVAC

• Important to minimize over-sizing and maximizing efficiency

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Purpose of Loads

• Load used to select system and size equipment• Size of the system limits equipment options

Example: Small water cooled chillers not readily available

• Other factors also influence the system selection: ‒ Owner priorities‒ Space availability‒ Acoustics‒ Exterior equipment restrictions‒ Etc.

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Load Calculation

• Software often used to perform the analysis because of the complexity

• Goal of the calculation is to establish the peak load experienced by the building

• Complexity is a result of the many variables that must be considered

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Load Calculation

• Heating• Cooling

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Load Calculations

• Items accounted for in a peak load calculation• Weather conditions • Envelope (walls, floors, windows, roof, etc.)• Thermostat set point (summer vs. winter)

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Climate Zones

Marine (C) Moist (A)Dry (B)

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Cooling Loads

• Loads considered specific to cooling‒ Internal loads (people, equipment, lights, plug

loads)‒ Time of day and orientation (sun position)

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Heating Loads

• Heating peak load does not include the heat gain from sun and internal loads

• Worst case for heating occurs at night‒ No sun, people, or equipment loads

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Building Examples

1. Multi-use Facility2. Medical Office Building3. Hospital4. Campus w/ central plant

1

3

2

56

4

Multi-use Facility

• Occupancy – 140 persons• 6 a.m. – 6 p.m. Monday - Friday

• Building Characteristics• Single story• 20,000 square feet (250’ x 80’)• Standard construction

57

Medical Office Building

• Occupancy – 400 persons• 8 a.m. – 5 p.m. Monday - Friday

• Building Characteristics• Three stories• 40,000 square feet (200’ x 200’)/floor• Standard construction

58

Hospital

• Occupancy – • Patient areas: 24 hours per day• Office areas: 8 a.m.– 5 p.m. Monday-Friday

• Building Characteristics:• Four story with basement• 140,000 square feet per floor• Standard construction

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Climate Zones

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Chicago

Houston

Anchorage

Peak Loads

Heating

Cooling

61

62

37%26%

47%10%

32%

Multi-use3%

Operational Load

• Peak is a worst case moment in time• Many variable change even during a peak day

‒Change in outside temp from morning to night‒Fluctuation in occupancy ‒Equipment/Lighting loads are not consistent‒Changes in thermostat set points

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Operation vs Peak

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15% Over-sizedCooling

Design Heating Peak

Design Cooling Peak

Simultaneous Heating & Cooling

25% Over-sized Heating

Over-sizing

• Result of conservative initial assumptions• Exaggerated by the idea that bigger is better• Belief that safety factors is needed to protect themselves from under-sizing the equipment

• Select components that are the next size larger to be ‘safe’ when between sizes

BIGGER IS NOT BETTER IN HVAC DESIGN!

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Conservative Design

Justification for over-sizing:• Systems may not be installed per the plans• Weather extremes will exceed the design values• Changes in number occupants, thermostat set points, equipment/lights, etc. from that initially defined

• Changes in operation i.e. control settings and/or sequenced altered from that in the specification

• Changes in operational characteristics as a result of maintenance (or lack there of) and age of the system

66

Poor Design Practice

• Rules of thumb • Time / budget

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Better Design

• Designers do not always look at the part load operation when selecting and specifying equipment

• Redundancy is required on some projects (N+1)• May be good practice when not required

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Revised CoolingDesign Peak

Revised Heating Design Peak

Impact of over-sizing

• Pumps must meet operational loads therefore affecting the position on the pump curve compared to the original (over-sized) selection

• Affects the pump efficiency

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