Upload
amhosny64
View
219
Download
0
Embed Size (px)
Citation preview
8/13/2019 Intro. to Commercial Building Control Strategies
1/76
8/13/2019 Intro. to Commercial Building Control Strategies
2/76
IntroductiontoCommercialBuildingControlStrategiesand
TechniquesforDemandResponse
NaoyaMotegi
MaryAnnPiette
DavidS.Watson
SilaKiliccote
PengXu
LawrenceBerkeleyNationalLaboratory
MS90R3111
1CyclotronRoad
Berkeley,California94720
May22,2007
ThisworkdescribedinthisreportwascoordinatedbytheDemandResponseResearch
CenterandfundedbytheCaliforniaEnergyCommission,PublicInterestEnergy
ResearchProgram,underWorkforOthersContractNo.50003026andbytheU.S.
DepartmentofEnergyunderContractNo.DE-AC02-05CH11231.
LBNLReportNumber59975
8/13/2019 Intro. to Commercial Building Control Strategies
3/76
i
Acknowledgements
Theworkdescribed in thisreportwascoordinatedby theDemandResponseResearch
CenterandfundedbytheCaliforniaEnergyCommission(EnergyCommission),Public
InterestEnergyResearch(PIER)Program,underWorkforOthersContractNo.50003
026
andby
the
U.S.
Department
of
Energy
under
Contract
No.
DE
AC02
05CH11231.
Theauthorswishtothanktheengineersandstaffateachbuildingsite. Specialthanksto
RonHofmann forhis conceptualizationof thisprojectandongoing technical support.
Thanks also to Laurie ten Hope, Mark Rawson, and Dave Michel at the California
Energy Commission. Finally, thanks to the Pacific Gas and Electric Company who
fundedtheAutomatedCPPresearch.
We appreciate the helpful comments providedby the peer reviewers of this report:
Douglas B. Nordham (EnerNOC), Austen DLima (San Diego Gas and Electric
Company),SteveGreenbergandBarbaraAtkinson(LBNL).
Pleasecite
this
report
as
follows:
Motegi,N.,M.A.Piette,D.S.Watson,S.Kiliccote,P.Xu.2006.IntroductiontoCommercial
Building Control Strategies and Techniques for Demand Response. California Energy
Commission,PIER.LBNLReportNumber59975.
8/13/2019 Intro. to Commercial Building Control Strategies
4/76
ii
Preface
The Public Interest Energy Research (PIER) Program supports public interest energy
research and development that will help improve the quality of life in Californiaby
bringingenvironmentallysafe,affordable,andreliableenergyservicesandproductsto
themarketplace.
The PIER Program, managed by the California Energy Commission (EnergyCommission),annuallyawardsupto$62milliontoconductthemostpromisingpublic
interestenergyresearchbypartneringwithResearch,Development,andDemonstration
(RD&D)organizations,includingindividuals,businesses,utilities,andpublicorprivate
researchinstitutions.
PIERfundingeffortsarefocusedonthefollowingsixRD&Dprogramareas:
BuildingsEndUseEnergyEfficiency
Industrial/Agricultural/WaterEnd
Use
Energy
Efficiency
RenewableEnergy
EnvironmentallyPreferredAdvancedGeneration
EnergyRelatedEnvironmentalResearch
EnergySystemsIntegration
WhatfollowsisthefinalreportfortheStatewideAutoDRCollaborationProject,50003
026, conducted by Lawrence Berkeley National Laboratory. The report is entitled
Introduction toCommercialBuildingControlStrategiesandTechniques forDemand
Response.ThisprojectcontributestotheEnergySystemsIntegrationProgram.
FormoreinformationonthePIERProgram,pleasevisittheEnergyCommissionsWeb
site at: http://www.energy.ca.gov/research/index.html or contact the Energy
CommissionsPublicationsUnitat9166545200.
8/13/2019 Intro. to Commercial Building Control Strategies
5/76
iii
TableofContents
ExecutiveSummary..................................................................................................................... 1
1. Introduction ......................................................................................................................... 1
1.1. BackgroundandOverview........................................................................................ 1
1.2. Objectives ..................................................................................................................... 1
1.3. ResearchScope ............................................................................................................ 11.4. BenefitstoCalifornia .................................................................................................. 3
1.5. ReportOrganization ................................................................................................... 3
1.6. BuildingOperationandEnergyManagementFramework .................................. 4
1.7. TermsandConceptsforDRStrategies .................................................................... 6
2. DemandResponseStrategyOverview ......................................................................... 10
2.1. HVACSystems.......................................................................................................... 10
2.2. LightingSystems....................................................................................................... 14
2.3. MiscellaneousEquipment........................................................................................ 16
2.4. NonComponentSpecificControlStrategies........................................................ 16
2.5. StrategiesUsedinCaseStudies .............................................................................. 16
3. DemandResponseStrategyDetail................................................................................ 19
3.1. HVACSystems.......................................................................................................... 19
3.1.1. Globaltemperatureadjustment...................................................................... 20
3.1.2. Passivethermalmassstorage ......................................................................... 25
3.1.3. Ductstaticpressuredecrease.......................................................................... 26
3.1.4. Fanvariablefrequencydrivelimit................................................................. 27
3.1.5. Supplyairtemperatureincrease .................................................................... 28
3.1.6. Fanquantityreduction .................................................................................... 29
3.1.7. Coolingvalvelimit........................................................................................... 30
3.1.8. Chilledwatertemperatureincrease............................................................... 31
3.1.9. Chillerdemandlimit........................................................................................ 32
3.1.10. Chillerquantityreduction............................................................................... 34
3.1.11. Reboundavoidancestrategies........................................................................ 36
3.2. LightingSystems....................................................................................................... 37
3.2.1. Zoneswitching ................................................................................................. 37
3.2.2. Luminaire/lampswitching.............................................................................. 38
3.2.3. Steppeddimming ............................................................................................. 41
3.2.4. Continuousdimming....................................................................................... 42
3.3. MiscellaneousEquipment........................................................................................ 43
3.4. NonComponentSpecificStrategies ...................................................................... 45
3.4.1. Demandlimitstrategy ..................................................................................... 45
3.4.2. Pricelevelresponsestrategy .......................................................................... 46
4. ImplementationofDRStrategies.................................................................................. 47
4.1. DRStrategyDevelopmentandCommissioning................................................... 47
8/13/2019 Intro. to Commercial Building Control Strategies
6/76
8/13/2019 Intro. to Commercial Building Control Strategies
7/76
v
ListofFigures
Figure1.Examplesofloadshapes ............................................................................................. 6
Figure2.HVACDRstrategydecisiontree ............................................................................. 11
Figure3.LightingDRstrategydecisiontree .......................................................................... 15
Figure4.FrequencyofDRstrategies....................................................................................... 18
Figure5.Temperature
drift
rate
allowed
under
ASHRAE
Standard
55 .......................... 218
Figure6.Zonesetpointsdeadband.......................................................................................... 22
Figure 7. Conceptual diagram of demand savings for typical HVACbased demand
responsestrategy ............................................................................................................... 24
Figure8.Luminaireswitchingalternaterowsofluminaires ............................................ 39
Figure9.Luminaireswitchingeveryotherluminaireineachrow.................................. 39
Figure10.Lampswitching middlelampsofthreelampfixtures..................................... 40
Figure11.Lampswitchinglampsineachluminaire ......................................................... 40
Figure12.Exampleofpricelevelzonesetpointcontrol....................................................... 46
Figure13.Demandsavingsintensitybyshedstrategy(W/ft2)............................................ 51
Figure14.OATvs.averagedemandsavings ......................................................................... 52
Figure15.Wholebuildinghourlydemandvs.OATanddemandsheds .......................... 54
ListofTables
Table1.Demandsidemanagementterminologyandbuildingoperations......................... 4
Table2.BuildingHVACtypes ................................................................................................. 11Table3.HVACdemandresponsestrategies .......................................................................... 12
Table4.DRstrategiesusedinLBNLAutoDRstudies(fullyautomated) ........................ 17
Table5.DRstrategiesusedincasestudies(manualorsemiautomated) ......................... 18
Table6.Conditionsforglobaltemperatureadjustment(GTA)........................................... 20
Table7.Conditionsforpassivethermalmassstorage.......................................................... 25
Table8.Conditionsforductstaticpressuredecrease ........................................................... 26
Table9.Conditionsforfanvariablefrequencydrivelimit .................................................. 27
Table10.Conditionsforsupplyairtemperaturereset ......................................................... 28Table11.Conditionsforfanquantityreduction.................................................................... 29
Table12.Conditionsforcoolingvalvelimit........................................................................... 30
Table13.Conditionsforchilledwatertemperatureincrease .............................................. 31
Table14.Conditionsforchillerdemandlimit........................................................................ 32
Table15.Conditionsforchillerquantityreduction............................................................... 34
Table16.Conditionsforzoneswitching................................................................................. 37
Table17.Conditionsforluminaire/lampswitching.............................................................. 38
Table18.Conditionsforsteppeddimming ............................................................................ 41Table19.Conditionsforcontinuousdimming....................................................................... 42
Table20.Recommendeddatacollectionpoints ..................................................................... 49
Table21.Demandsavingsinfluencefactors........................................................................... 51
8/13/2019 Intro. to Commercial Building Control Strategies
8/76
vi
Table22.StatisticalsignificanceofOATvs.demandsavings.............................................. 53
8/13/2019 Intro. to Commercial Building Control Strategies
9/76
vii
Abstract
Demand Response (DR) isa setof timedependentprogramactivitiesand tariffs that
seektoreduceelectricityuseorshiftusagetoanothertimeperiod. DRprovidescontrol
systems thatencourage load sheddingor load shiftingduring timeswhen theelectric
grid is near its capacity or electricity prices are high. DR helps to managebuilding
electricitycostsandtoimproveelectricgridreliability.
This report provides an introduction to commercial building control strategies and
techniquesfordemandresponse.Manyelectricutilitieshavebeenexploringtheuseof
critical peak pricing (CPP) and other demand response programs to help reduce
summer peaks in customer electric loads. This report responds to an identified need
amongbuildingoperatorsforknowledgetouseDRstrategiesintheirbuildings.These
strategiescanbeimplementedusingeithermanualorautomatedmethods.
The
report
compiles
information
from
field
demonstrations
of
DR
programs
in
commercialbuildings. The guide provides a framework for categorizing the control
strategies that have been tested in actual buildings. The guides emphasis is on
characterizinganddescribingDRcontrolstrategiesforairconditioningandventilation
systems.Thereisalsogoodcoverageoflightingcontrolstrategies. Theguideprovides
someadditionalintroductiontoDRstrategiesforothermiscellaneousbuildingenduse
systemsandnoncomponentbasedDRstrategies.
The core information in this report isbased on DR field tests in 28 nonresidential
buildings,mostofwhichwere inCalifornia,and the restofwhichwere inNewYorkState. The majority of the participatingbuildings were officebuildings. Most of the
Californiabuildingsparticipatedinfullyautomateddemandresponsefieldtests.
8/13/2019 Intro. to Commercial Building Control Strategies
10/76
1
ExecutiveSummary
Introduction
Demand Response (DR) isa setof timedependentprogramactivitiesand tariffs that
seek toreduceorshiftelectricityusage to improveelectricgridreliabilityandmanage
electricity costs. DR strategies provide control methodologies that enhance load
shedding or load shifting during times when the electric grid is near its capacity orelectricitypricesarehigh.Manyelectricutilitieshavebeenexploringtheuseofcritical
peakpricing(CPP)andotherdemandresponseprogramstohelpreducesummerpeaks
incustomerelectric loads.Recentevaluationshaveshown thatcustomershave limited
knowledgeofhow tooperate theirfacilities toreduce theirelectricitycostsunderCPP
(QuantumandSummitBlue2004).
Purpose
Thepurpose
of
this
report
isto
provide
an
introduction
to
commercial
building
control
strategiesandtechniquesfordemandresponse.Whileenergyefficiencymeasureshave
been widely understood by many audiences including facility managers, building
owners, control contractors, utility program managers, auditors, and policy makers,
therearenotmanydocumentsintroducingframeworksorguidelinesformeasuresand
strategiestoparticipateindemandresponseprograms.
Commercialbuildingshavebeenonlyminorparticipantsindemandresponseprograms.
This report is designed tobe an initial introduction to the technical capabilities of
existingbuildingequipmentandsystemsandtheirabilitytoprovidedemandresponsecontrolstrategies.WhilethefocusoftheguideisonDR,wehavefoundthattheprocess
ofdevelopingDRcontrolstrategiescanalsohelpidentifystrategiesforenergyefficiency
duringdailybuildingoperations.
ProjectObjectives
Thereportisauniqueguidethatcompilesinformationfromactualfielddemonstrations
of DR programs in commercialbuildings. The guide providesbackground technical
information
necessary
to
identify
and
enable
demand
response
control
strategies.
The
guideisintendedforusebybuildingprofessionalsincludingfacilitymanagers,building
owners,controlcontractors,buildingengineers,utilitypersonnel,andauditors.
ProjectOutcomes
Theguideprovidesa framework forcategorizing thecontrolstrategies thathavebeen
testedinactualbuildings.TheguidesemphasisisoncharacterizinganddescribingDR
control strategies for airconditioning and ventilation systems, plus lighting control
strategies. Theguideprovidessomeadditional introduction toDRstrategies forother
miscellaneousbuildingendusesystemsandnoncomponentbasedDRstrategies.Thesestrategiescanbeimplementedusingeithermanualorautomatedmethods.
8/13/2019 Intro. to Commercial Building Control Strategies
11/76
2
The core information in this report isbased on DR field tests in 28 nonresidential
buildings,mostofwhichwere inCalifornia,and the restofwhichwere inNewYork
State. The majority of the participatingbuildings were officebuildings. Most of the
Californiabuildingsparticipatedinfullyautomateddemandresponsefieldtests.
Heating, Ventilating, and Air Conditioning (HVAC). HVAC systems can be an
excellent resource for DR savings for the following reasons. First, HVAC systems
compriseasubstantialportionoftheelectricloadincommercialbuildings.Second,thethermal flywheel (thermal storage) effect of indoor environments allows HVAC
systems to be temporarily unloaded without immediate impact on the building
occupants. Third, it is common for HVAC systems tobe at least partially automated
withenergymanagementandcontrolsystems (EMCS).Toprovidereliable,repeatable
DRcontrol,itisbesttopreplanandautomateoperationalmodesthatwillprovideDR
savings.TheuseofautomationreducesthelaborrequiredtoimplementDRoperational
modeswhentheyaresignaled.
HVACbased DR strategies recommended for a given facility varybased onbuildingtypeandcondition,mechanicalequipment,andEMCS.Basedonthesefactors,thebest
DR strategies are those that achieve the aforementioned goals of meeting electricity
demandsavings targets while minimizing negative impacts on the occupants of the
buildings or the processes that they perform. This guide discusses the following DR
strategiesforHVACsystems,whicharebestsuitedtoachievethesegoals:
GlobalTemperatureAdjustmentofZones,and
SystemicAdjustmentstotheAirDistributionand/orCoolingSystems.
It is often difficult to estimate the demand savings achieved by HVAC strategies,
because the buildings HVAC electric load is dynamic and sensitive to weather
conditions, occupancy, and other factors. However, previous research has found that
HVAC demand as well as demand savings tend to have positive correlation with
outsideairtemperature(OAT).
Lighting.DRstrategiesforlightingcanalsobeeffectiveinreducingpeakdemand.Ona
hotsummerdaywhendaylightisinabundance,daylitand/oroverlitbuildingsarethe
best candidates for lighting demand savings. Since lighting produces heat, reducing
lighting levelswillalsoreduce thecooling loadwithin thespace (SezgenandKoomey
1998). Lighting DR strategies tend tobe simple and depend widely on wiring and
controls infrastructures. However, since lighting has safety implications and the
strategies tend tobe noticeable, they shouldbe carried out selectively and carefully,
considering the tasks in the spaceand ramificationsof reduced lighting levels for the
occupants.
DRcontrol
capability
of
lighting
systems
isgenerally
determined
by
the
characteristics
of the lighting circuit and the control system. Following is the list of lighting DR
strategiesdiscussedinthisguideinincreasingorderofsophistication:
Zoneswitching
8/13/2019 Intro. to Commercial Building Control Strategies
12/76
3
Fixtureswitching
Lampswitching
Steppeddimming
Continuousdimming
Miscellaneous Equipment. There is also demand savings potential for certain other
equipment inboth commercialand industrialbuildings.Equipmentorprocesseswith
thedemand savingpotentialsdiscussed in this reportare fountainpumps,antisweatheaters, electric vehicle chargers, industrialprocess loads, cold storage, and irrigation
waterpumps.
NonComponentSpecific Strategies. Other effective DR strategies focus on controls
settings rather than on specific equipment. Such strategies highlighted in this report
includedemandlimitstrategyandsignallevelresponsestrategy.
Conclusions
HVAC systems canbe an excellent resource for DR shed savingsbecause; 1) HVACsystems create a substantial electric load in commercial buildings, 2) the thermal
flywheel effect of indoor environments allows HVAC systems to be temporarily
unloadedwithoutimmediateimpacttothebuildingoccupants,and3)itiscommonfor
HVACsystemstobeatleastpartiallyautomatedwithEMCSsystems.
ForHVACDRstrategies,globaltemperatureadjustmentofzonesistheprioritystrategy
thatbestachievestheDRgoal.Incontrast,systemicadjustmentstotheairdistribution
and/orcoolingsystemscanbedisruptivetooccupants. DRstrategiesthatslowlyreturn
the system to normal condition (rebound avoidance) shouldbe considered to avoid
unwanteddemandspikescausedbyanimmediateincreaseofcoolingload.
Lighting DR strategies tend tobe simple and provide constant, predictable demand
savings.Since lightingproducesheat, reducing lighting levelsmay reduce thecooling
load and/or increase the heating load within the space. The resolution of lighting
controlstendstobelowerthanthatofHVACcontrols. Alsolightingsystemsareoften
not automated with EMCS. These issues canbe major obstacles for automation of
lightingDRstrategies.
IfaDRstrategycanbeachievedwithoutanyreductioninservice,thestrategyshouldbe
considered as permanent energy efficiency opportunity rather than a temporary DR
strategy. That is, it shouldbe performed on nonDR days as well. The process of
commissioning shouldbe applied to each phase of DR control strategy application,
including planning, installation, and implementation to make sure the goal of DR
controlisachieved.
Recommendations
The information in this report should be disseminated to key personnel who are
involved inDR implementation including facilitymanagers,buildingowners,controls
contractors,andauditors.Disseminating this informationwillhelpprovideacommon
understanding of DR control strategies and development procedures to enable these
8/13/2019 Intro. to Commercial Building Control Strategies
13/76
4
strategies.The report isnotanexhaustive listofallDR strategies.Further research is
needed tobetterunderstand the peak demand reduction potential and capabilitiesof
thesestrategiesforvariousbuildingtypesindifferentclimatesandoccupancypatterns.
One specific technical development needed is to explore the design and operation of
simplifiedpeakelectricdemandsavingsestimationmethodsandtools.Currentauditors
and building engineers have widely varying methods to estimate peak demand
reductions
for
various
strategies.
BenefitstoCalifornia
This guide isbased primarily on case studies in California and is intended to help
streamline the DR control strategy implementation process and increase successful
participation in DR programs in California. Peak demand reduction and demand
responsearekeypartsofthestatesenergypolicies.
8/13/2019 Intro. to Commercial Building Control Strategies
14/76
1
1. Introduction
1.1. Background and Overview
Demand Response (DR) isa setof timedependentprogramactivitiesand tariffs that
seek toreduceorshiftelectricityusage to improveelectricgridreliabilityandmanage
electricity costs. DR strategies provide control methodologies that enhance load
shedding or load shifting during times when the electric grid is near its capacity or
electricitypricesarehigh.Manyelectricutilitieshavebeenexploringtheuseofcritical
peakpricing(CPP)andotherdemandresponseprogramstohelpreducesummerpeaks
incustomerelectric loads.Recentevaluationshaveshown thatcustomershave limited
knowledgeofhow tooperate theirfacilities toreduce theirelectricitycostsunderCPP
(QuantumandSummitBlue2004).
1.2. Objectives
Thepurposeofthisreportistoprovideanintroductiontocommercialbuildingcontrol
strategiesandtechniquesfordemandresponse.Whileenergyefficiencymeasureshave
been widely understood by many audiences including facility managers, building
owners, utility program managers, auditors, and policy makers, there are not many
documents introducing frameworks or guidelines for measures and strategies to
participateindemandresponseprograms.Commercialbuildingshavebeenonlyminor
participants in demand response programs. This report is designed tobe an initial
introduction to the technical capabilities of existingbuilding equipment and systems
andtheirability toprovidedemandresponsecontrolstrategies.Whilethe focusof the
guideisonDR,wehavefoundthattheprocessofdevelopingDRcontrolstrategiescan
alsohelpidentifystrategiesforenergyefficiencyduringdailybuildingoperations.
Thisreportwillhelpunderstandtechnicalaspectsofdemandresponsecontrolstrategies.
HVAC systems are often complex combinations of components with minimal sensor
points, limited trend logging, and poorlycommissioned sequences of operation. The
processofdevelopingDRcontrolstrategieswillprovidevaluablepeakdemandsavings
in
addition
to
new
insights
for
improving
energy
efficiency
during
dailybuilding
operations. The report is the first guide that compiles information from actual field
demonstrations of DR programs in commercial buildings. The guide provides the
technical information necessary to install demand response control strategies for
audiencesincludingfacilitymanagers,buildingowners,andauditors.
1.3. Research Scope
This report provides an introduction to commercial building control strategies for
demand response that havebeen fieldtested in actual commercialbuildings. Thesestrategiescanbeimplementedusingeithermanualorautomatedcontrolmethods.The
authorscompiledinformationfromactualfielddemonstrationsincommercialbuildings
that have participated in DR programs in California and New York. Thus, the guide
8/13/2019 Intro. to Commercial Building Control Strategies
15/76
2
providesaframeworkforcategorizingcontrolstrategiesthathavebeentestedinactual
buildings.Theguideemphasizesstrategiesforairconditioningandventilationsystems.
There is also ample coverage of lighting control strategies. In addition, the guide
provides some introduction toDR strategies forotherbuilding enduse equipment. It
alsodiscussesnoncomponentbasedDRstrategies.
Thereportisauniqueguidethatcompilesinformationfromactualfielddemonstrations
of DR programs in commercialbuildings. The guide providesbackground technicalinformationnecessary to identifyandenabledemandresponsecontrolstrategies. The
guideisintendedforusebybuildingprofessionalsincludingfacilitymanagers,building
owners,controlcontractors,buildingengineers,utilitypersonnel,andauditors. Itmay
alsobeofinteresttoresearchers,energyplanners,andpolicymakers.
Thedemandresponsecontrolstrategiesdiscussedinthisguidewouldberecommended
foreithersemi orfullyautomatedDR,thoughtheymaybeusedformanualDRaswell.
SeeSection1.6onLevelsofAutomationforDRfordefinitionsofDRautomationtypes.
LawrenceBerkeleyNationalLaboratory(LBNL)hasbeenconductingaseriesofresearchprojectsanddemonstrationsoffullyautomatedDRstrategies(referredtoasLBNLAuto
DR) (Piette et al. 2005a, 2005b, and 2006). This report is based on the cumulative
experiencesandfindingsfromtheLBNLAutoDRdemonstrationstudiesalongwiththe
othercasestudiesreferencedinthisreport.
The core information in this guide isbased on DR field tests in 28 nonresidential
buildings, most of which were in California. DRdata from the Energy Commissions
EnhancedAutomationcasestudiesinCaliforniawerealsoevaluated(CEC2006a),along
with case studies from New York (NYSERDA 2006). Case studies to date have
emphasized certain types ofbuildings, while otherbuilding types have not yetbeen
studied. The majority of the participants havebeen officebuildings. Otherbuilding
typesincludeseveralretailsites,asupermarket,publicassemblybuildings,acafeteria,a
postoffice,amuseum,ahighschool,datacenters,andlaboratorybuildings.Thesample
didnot includeanyhotelorhealthcarebuildings,butmanyofthestrategiesdiscussed
maybeapplicabletothesebuildingtypes.MostoftheCaliforniabuildingsparticipated
infullyautomateddemandresponsefieldtests.
It is also important to consider the HVAC systems that the case studies and
demonstrationbuildingsused.Builtupvariableairvolume(VAV)systemswithcentral
coolingplantsdominatethesample,althoughmanyofthesmallerbuildingsuserooftop
packagedunitsystems.ManyofthelesscommonHVACsystemswerenotincludedin
thecasestudies.Thisreportdidnotidentifyanywatersourceheatpumporgascooling
sitesthathaveimplementedDRstrategies.
Thisguidefocusesonsummerpeakdemandreductionstrategies,althoughlightingDR
strategies can be utilized to reduce winter demand as well. Most of the examplesintroducedinthisreportarebasedoncasestudiesinthenorthernorcentralCalifornia
region,whichhasamildorhotanddry climate.This reportdoesnot include careful
considerationoftheapplicationofDRtofacilitiesinhotandhumidclimates.
8/13/2019 Intro. to Commercial Building Control Strategies
16/76
3
This guide is intended as a starting point for organizing and presenting such
information.Although the information isbasedona limitednumberofbuildings, the
authors compiled the existing case study data because of the need for organized
informationonthissubject.Theinformationinthisguidehasbeenevaluatedbyseveral
professionalengineersandenergyanalyststobringbuildingHVACandcontrolstheory
intothediscussionofDRstrategies.
1.4. Benefits to California
This guide isbased primarily on case studies in California and is intended to help
streamline the DR control strategy implementation process and increase successful
participation in DR programs in California. Peak demand reduction and demand
responsearekeypartsofthestatesenergypolicies.
1.5. Report Organization
Thissectiondiscussestheguidesbackground,objectives,organization,anddefinitions,
terms, and concepts.Section 2provides anoverviewof the characteristics ofdemand
response control strategies. These control strategies are presented in four categories:
HVAC, lighting, miscellaneous equipment, and nonendusespecific measures. In
Section 3, ten HVAC strategies, four lighting strategies, six miscellaneous equipment
strategies, and two nonendusespecific strategies are described in detail along with
their system requirements and sequences of operation. The appendices provide more
detailed descriptions and case study examples of each strategy. Section 4 discusses
commissioningandtheEMCSdatacollectionprocedure;measurementandverificationofdemandresponsestrategiesisveryimportanttoachievesuccessfuldemandresponse.
StatisticalfindingsfromtheDRstrategycasestudiesarealsointroducedinthissection.
ThisreportreviewedDRstrategiesthathavebeendemonstrated inactualbuildings in
previousresearchactivities,including;
EnhancedAutomation CaliforniaEnergyCommission(CEC2006a)
RealTime Price Response Program Independent System Operator New
England(ISONewEngland2003) AutomatedDemandResponse LawrenceBerkeleyNationalLaboratory(LBNL)
(Piette2005a,2005b)
AutomatedCriticalPeakPricing LBNL(Piette2006)
DemandShiftingwithThermalMass LBNL(Xu2004,2006)
Peak Load Reduction Program New York State Energy Research and
DevelopmentAuthority(NYSERDA2006andSmith2004)
NewYorkTimes LBNLandNewYorkTimes(Kiliccote2006)
DemandResponse
Program
Evaluation
Quantum
Consulting
and
Summit
Blue
Consulting(QuantumandSummitBlue2004)
8/13/2019 Intro. to Commercial Building Control Strategies
17/76
4
1.6. Bui lding Operation and Energy Management Framework
Thissectionprovidesbackground information forvariousenergyanddemandcontrol
activities.Italsoprovidesdefinitionsoftermsandconceptsusedinthisguide.
During the past few decades, knowledge and use of practices to minimize energy
consumption in commercial building design and operations has been improved to
achievegreater
levels
of
energy
efficiency.
Related
to
reduction
of
energy
use
isenergy
cost minimization. Electricity cost minimization inbuilding operations requires close
attentiontothestructuresofelectricitytariffs,whichconsiderthetimeandthequantity
ofelectricityused.Electricitypricing structurescanbecomplex, including timeofuse
charges, demand ratchets, peakdemand charges, and other related features. New
demand response programs and tariffs that utilities or independent system operators
(ISO) offer provide greater incentives to consider the use of sophisticated building
operationaland control strategies that reduceelectricityuseduringoccasionalevents.
Following are three definitions forbuilding design and operational control strategies.
Table 1 provides insight into the motivations, design, and operation of these three
strategies(Kiliccote2006).
Energy Efficiency and Conservation: Energy efficiency lowers energy use while
providing the same levelof service.Energy conservation reducesunnecessaryenergy
use. Both energy efficiency and conservation provide environmental protection and
utilitybillsavings.Energyefficiencymeasurescanpermanentlyreducepeakdemand
byreducingoverallconsumption.Inbuildingsthisistypicallydonebyinstallingenergy
efficientequipment
and/or
operating
buildings
efficiently.
Energy
efficient
operations,
a
key objective of newbuilding commissioning and retrocommissioning (for existing
buildings),requirethatbuildingsystemsoperateinanintegratedmanner.
Table 1. Demand side management terminology and building operationsEfficiencyandConservation
(Daily)
PeakLoadManagement
(Daily)
DemandResponse(Dynamic
EventDriven)
Motivation
EconomicEnvironmentalprotectionResourceavailability
TOUsavingsPeakdemandcharges
Gridpeak
Price(economic)Reliability
Emergencysupply
DesignEfficientshell,equipment,systems,andcontrolstrategies
LowpowerdesignDynamiccontrolcapability
OperationsIntegratedsystemoperations
DemandlimitingDemandshifting
DemandsheddingDemandshiftingDemandlimiting
Initiation Local Local Remote
Peak Load Management: Daily peak load management hasbeen conducted in many
buildingstominimizetheimpactofpeakdemandchargesandtimeofuserates.Typical
peak load management methods include demand limiting and demand shifting.
8/13/2019 Intro. to Commercial Building Control Strategies
18/76
5
Demand Limiting refers toshedding loadswhenpredeterminedpeakdemand limits
areabouttobeexceeded.Demandlimitscanbeplacedonequipment(suchasachiller
or fan), systems (such as a cooling system), or a wholebuilding. Loads are restored
whenthedemandissufficientlyreduced.Thisistypicallydonetoflattentheloadshape
when the monthly peak demand is predetermined. Demand shifting is achievedby
changing the time that electricity isused. Thermal energy storage is an example of a
demand
shifting
strategy.
Thermal
storage
can
be
achieved
with
active
systems
such
as
chilled water or ice storage, or with passive systems such as precooling ofbuilding
mass.InCalifornia,timedependentvaluation(TDV)1isalsoinuseforbuildingenergy
code compliance calculations requiredby the statebuilding energy code (Title 24) to
take into account the time that electricity is used during the year (CEC 2005). TDV
acknowledgesthatsomeefficiencymeasuresreducesummerpeakelectricdemandmore
thanothers.
DemandResponse:Demandresponseisdynamicandeventdrivenandcanbedefined
asshorttermmodifications incustomerenduseelectric loads in response todynamicprice and reliability information. Demand response programs may include dynamic
pricing and tariffs, priceresponsive demand bidding, contractually obligated and
voluntarycurtailment,anddirectloadcontrolorequipmentcycling.Asdiscussedabove,
Demand limiting and shifting canbe utilized for demand response. DR can alsobe
accomplishedwithdemandshedding,whichisatemporaryreductionorcurtailmentof
peakelectricdemand.Ideallyademandsheddingstrategywouldmaximizethedemand
reductionwhileminimizinganylossofbuildingservices.
Figure 1 illustrates concept of typical electric load shapes for each energy/demandcontrolactivitydescribedabove.
1Time dependent valuation (TDV) is an energy cost analysis methodology that accounts for
variationsincostrelatedtotimeofday,seasons,geography,andfueltype. InCalifornia,under
TDV thevalueofelectricitydiffersdependingon timeofuse (hourly,daily, seasonal)and the
valueofnaturalgasdiffersdependingonseason.TDVisbasedonthecostforutilitiestoprovide
theenergyatdifferenttimes.
8/13/2019 Intro. to Commercial Building Control Strategies
19/76
6
0
1
2
3
4
5
6
7
8
9
10
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
0:00
Time of day
Buildingdemand
Baseline
Energyefficiency
Demandlimiting
Demand
shedding
Demandshifting
*Thischartisconceptual;thedataarenotfromactualmeasurements.
Figure 1. Examples of load shapesLevelsofAutomation forDR:Varying levelsofautomation forDRcanbedefinedas
follows. Manual Demand Response involves a laborintensive approach such as
manually turning off or changing comfort set points at each equipment switch or
controller. SemiAutomated Demand Response involves a preprogrammed load
sheddingstrategyinitiatedbyapersonviacentralizedcontrolsystem.FullyAutomated
DemandResponsedoesnotinvolvehumanintervention,butisinitiatedbyanEnergy
ManagementControlSystem(EMCS)inahome,building,orfacilitythroughreceiptof
anexternalcommunicationssignal,receiptofwhichinitiatespreprogrammedsheddingstrategies.
Recent evaluations have shown that customers have limited knowledge of how to
operatetheirfacilitiestoreducetheirelectricitycostsundercriticalpeakpricingorCPP
(Quantum and Summit Blue 2004). While lack of knowledge of how to develop and
implementDRcontrolstrategies isabarrier toparticipation inDRprograms likeCPP,
anotherbarrieristhelackofautomationinDRsystems.MostDRactivitiesaremanual
andrequirepeopletofirstreceiveemails,phonecalls,andpagersignals,andsecondly
forpeopletoactonthesesignalstoexecuteDRstrategies(Piette2006).
1.7. Terms and Concepts for DR Strategies
Thetermsdefinedbelowdescribekeyconceptsofdemandresponsecontrolstrategies.
Thesetermsareusedthroughoutthisreport.
Reductioninservice:Demandresponsestrategiesachievereductionsinelectricdemand
by temporarilyreducing the levelofservice in the facility.HVACand lightingare the
systemsmost commonlyadjusted toachievedemand response savings in commercialbuildings.Thegoalofdemandresponsestrategiesistomeetthedemandsavingstargets
while minimizing any negative impacts on the occupants of the buildings or the
processesthattheyperform.
8/13/2019 Intro. to Commercial Building Control Strategies
20/76
7
Occupant satisfaction: Occupant satisfaction shouldbe maintainedby adjusting DR
strategies tominimizethereduction inservice,so that theoccupantsdonotnotice the
changeinservice(detectability),oratleastsothattheoccupantscanacceptthechanges
(acceptability). Many studies have addressed the effect of temperature changes or
lighting changes on occupant detectability, acceptability, and task performance.
Newsham et al. conducted an extensive literature search on these studies (Newsham
2006).
OnecommonquestionregardingDRstrategies is: Ifyoucanuseastrategy forashort
period,whynotuseitallthetime?Eveniftheoccupantsdonotnoticethereductionin
service,theoccupantsproductivitymaybehigherwhenthespaceconditionsarecloser
to the occupants desirable conditions. Differencesbetween the impacts of shortterm
and longterm space condition changes are yet unknown. Daily demand savings
associatedwithreductioninserviceshouldbeconsideredcarefully.SeeLinkstoretro
commissioningbelowfordiscussionofrelatedtopics.
Sharedburden:DRstrategies thatshare theburdenevenly throughout the facilityare
least likely to have negative effects onbuilding occupants. For example, if it were
possibletoreducelightinglevelsthroughoutanentirefacilityby25%duringaDRevent,
impacts tooccupantsmightbeminimal.However, turningoff allof the lights inone
quadrantofanoccupied spacewouldnotbeacceptable. InHVAC systems, strategies
thatreduceloadevenlythroughoutallzonesofafacilityaresuperiortothosethatallow
certainareas(suchasthosewithhighsolargains)tosubstantiallydeviatefromnormal
temperature ranges. By combining demand savings from shed in each component of
HVAC and lighting systems (and other loads, if available), the impact on eachcomponentisminimizedandthedemandsavingspotentialisincreased.
Closedloop control: Comfort is maintained in modernbuildings through the use of
closed loop controls. Sensors are used to measure important parameters such as
temperature,andactuatorsadjustdampersorvalvestomaintainthedesiredsetpoints.
Theeffectofthevalveoractuatoronthecontrolledzoneorsystemismeasuredbythe
sensor, hence closing the (control) loop. Control subsystems for which there is no
feedbackfromsensorsareknownasopenloopcontrols.
TomaintainpredictableandmanagedreductionsofserviceduringDRevents,strategies
shouldmaintaintheuseofclosedloopcontrolwhereverpossible.However,closedloop
control may become an obstacle to achieve demand savings when the final target
parameter cannotbe changed through centralized control. (For example, pneumatic
control systems cannot change zone setpoints from centralized control, while typical
directdigitalcontrolsystemscan.)Forinstance,ifsupplyairtemperatureisraisedina
closedloopcontrolsystemtoreducechillerdemand,thefanspeedsuptodelivermore
air to satisfy the zone setpoints and fails to shed HVAC demand, unless the zone
setpointsareincreased.
Granularity of control: For the purposes of DR control inbuildings, the concept of
granularityreferstotheamountoffloorareacoveredbyeachcontrolledparameter(e.g.
8/13/2019 Intro. to Commercial Building Control Strategies
21/76
8
temperature).Ifthespacehasmanyzonesthatcanbeseparatelycontrolled,thecontrol
strategyisconsideredhighlygranular.InHVACsystems,theabilitytoeasilyadjustthe
temperaturesetpointofeachoccupiedspace isahighlygranularwaytodistribute the
DR shed burden throughout the facility. Less granular strategies such as making
adjustments tochillersandothercentralHVACequipmentcanprovideeffective shed
savings,butcancausetemperatureinsomezonestodriftoutofcontrol.Granularityof
control
can
also
allow
building
operators
to
create
DR
shed
behaviors
that
are
customized for their facility.Anexamplewouldbe to slightly increasealloffice zone
temperaturesetpoints,butleavecomputerroomsetpointsunchanged.
Resolutionofcontrol:Higherresolutionofcontrolincreasestheflexibilitytoadjustthe
levelofDRcontrolwithinadesirablerange.Higherresolutionofcontrolalsoenhances
thecapabilityoframpingup thechangeofDRcontrolparameters.HVACparameters
canoftenbecontrolledwithhighresolution;inmanysystemstemperaturesetpointscan
beadjustedbyas littleas0.1F.Although somemodern fluorescentdimmingballasts
can adjust individual lamps light output in 1% increments, most commercial lampballastsareonlycapableofturninglampsonoroff.
Rebound: At the end of each DR event, the affected systems must return to normal
operation.When lighting strategies areused forDR,normaloperation is regainedby
simplyreenablingall lightingsystems totheirnormaloperation.Lightscomebackon
as commandedby time clocks, occupancy sensors, or manual switches. There is no
reasonforlightingpowertojumptolevelsthatarehigherthannormalforthatperiod.
However, without special forethought, HVAC systems tend to use extra energy
followingDReventstobringsystemsbacktonormalconditions.Extraenergyisusedto
removeheatthatistypicallygainedduringthereducedservice levelsoftheDRevent.
ThispostDReventspikeisknownasrebound. Tominimizethechanceofhighdemand
chargesandtoreducenegativeeffectstotheelectricgrid,reboundshouldbeminimized
throughuseofagracefulreturntonormalstrategy.ThesimplestcaseiswheretheDR
eventendsorcanbepostponeduntilthebuildingisunoccupied.Ifthisisnotpossible,
strategies that allow HVAC equipment to slowly ramp up or otherwise limit power
usageduringthepostDRperiodshouldbeused.
Links to retrocommissioning:Assuming theHVACand lightingsystemsarealready
operatedtoachieveoptimaloccupantsatisfactionandminimizeenergyconsumptionin
their normal operation, the implementation of DR may cause a reduction in service.
However,therearemanycasesinrealitywherethesystemsarenotoperatedoptimally.
Inthesecases,itmaybepossibletoreduceelectricdemandwithoutreductioninservice.
Ifafacilityfindssuchastrategy,itshouldbeconsideredapermanentenergyefficiency
opportunityratherthanatemporaryDRstrategy,andshouldbeperformedonnonDR
daysaswell.
Planning a DR strategy can be a good opportunity to examine the sequence and
parameters of building control. While facility managers may be concerned about
deviations from current operation only for energy efficiency, they may be more
8/13/2019 Intro. to Commercial Building Control Strategies
22/76
9
motivated if the goal isboth energy efficiency and DRbecause the occupants canbe
morepermissiveunderaDRsituationinmanycases.Onceconfirmedthatthestrategy
doesnotnegatively impactthelevelofservice,thestrategycanbeoperatedonadaily
basis.
TheLBNLAutoDRstudies foundseveralcaseswhereDRstrategiesmerely impacted
thelevelofserviceandincorporatedthestrategiesintheirdailyoperation(Pietteetal.
2005a,2005b,2006).Inoneexample,aductstaticpressureresetstrategywasusedforabuildingwithpneumaticzone controls.Through thiseffort todevelop shorttermDR
strategies,theductstaticpressurewasresettooperatelowerduringalloperatinghours.
In another case, reduction in service actually improved occupant comfort or
productivityinsomezonesthatwereovercooledduringnormaloperation.Thesecases
can be viewed as classic retrocommissioning opportunities, identified through the
processofdevelopingDR strategies. Inother instances,when examining electric load
shapes, the team found equipment, such as fans or process equipment, running
unnecessarilyatnight.Inaddition,ifsystemsinafacilityareoperatingpoorlyduetodesignorcommissioning
issues, it maybe more difficult to implement effective DR strategies. For example, if
zones are overcooled due to excessive minimum airflows or low supply air
temperatures, raising zone temperature setpoints during a DR event will not save
energy.
DRstrategycommissioning:Theprocessofcommissioningshouldbeapplied toeach
phase of DR control strategy application including planning, installation, and
implementationtomakesurethatthegoalofDRcontrol tomaximizedemandsavings
andminimizeimpacttooccupants isachieved.Thecommissioningprocedureandkey
issuesaredescribedinSection4.1.
DesignofDRcontrol strategieswould ideally takeplaceduring thenewconstruction
commissioning phase and be incorporated into the commissioning process. A
demonstrationof this concept isbeingplannedat theNewYorkTimesHeadquarters
building(Kiliccoteetal.2006).
8/13/2019 Intro. to Commercial Building Control Strategies
23/76
10
2. Demand Response Strategy Overview
This section provides an overview of demand response control strategies. These
strategies are categorized into four areas: HVAC, lighting, miscellaneous equipment,
andnoncomponentspecificmeasures.Thedetailsofeachstrategyaredescribedinthe
followingsection.
2.1. HVAC Systems
HVAC systems canbe an excellent resource forDR shed savings for several reasons.
First,HVACsystemscreateasubstantialelectricdemandincommercialbuildings,often
more thanone thirdof the totaldemand.Second, the thermalflywheeleffectof indoor
environments allows HVAC systems tobe temporarily unloaded without immediate
impacttothebuildingoccupants.Third,itiscommonforHVACsystemstobeatleast
partiallyautomatedwithEMCS.
However,therearesignificanttechnicalchallengestousingcommercialHVACsystemstoprovideDRsavings.Thesesystemsaredesigned toprovideventilationandthermal
comfort to the occupied spaces. Operational modes that provide reduced levels of
service or comfort are rarely included in the original design of these facilities. To
provide reliable, repeatable DR sheds it isbest to preplan and automate operational
modes that will provide DR savings. The use of automation reduces labor costs
associatedwiththeimplementationofDRoperationalmodes.
HVACbasedDRstrategiesrecommendedforagivenfacilityvarybasedonthetypeand
conditionofthebuilding,mechanicalequipment,andEMCS.Basedonthesefactors,thebestDR strategiesare those thatachieve theaforementionedgoalsofmeetingelectric
demand savings targets while minimizing negative impacts on the occupants of the
buildingsortheprocessesthattheyperform.ThefollowingDRstrategiesareprioritized
toachievethesegoals:
GlobalTemperatureAdjustmentofZones
SystemicAdjustmentstotheAirDistributionand/orCoolingSystems
It is often difficult to estimate the demand savings that willbe achievedby HVACstrategies,becauseHVACcoolingloadisdynamicandsensitivetoweatherconditions,
occupancy, and other factors. However, previous research has found that the HVAC
demand and its demand savings tend to have positive correlation with outside air
temperature(OAT).
In all field tests that used HVACbased DR strategies, upon initiation of DR events,
temperatures in occupied zones drifted from normal levels at rates well within the
acceptablerateofchangespecificationallowedinASHRAEStandard552004(ASHRAE
2004).DRstrategiesused toreturnHVACsystemstonormaloperationshouldalsobe
designed to limit the rate of temperature change so as to not exceed the ASHRAE
standard. DR strategies that slowly return the system to normal condition have the
additionalbenefitoflimitingrebound.
8/13/2019 Intro. to Commercial Building Control Strategies
24/76
11
HVAC strategies canbe categorizedby the system targeted for control modification.
Theseincludezonecontrol,airdistribution,andcentralplant,inorderofrecommended
priority. Where practical, DR strategies that use temporary modifications to zone
temperaturesetpointsarerecommended.Thisrecommendationisbasedonmaximizing
DRshedsavingseffectivenesswhileminimizingthepotentialforoccupantdiscomfort.
Figure2showsthebasicconceptoftheHVACDRstrategydecisiontree.
START
Zone
control
DDC zone
control?
Y NDDC zone
control?
Y N
Central plant
control
Air
distribution
control
Air distribution
System DDC?
Y NAir distribution
System DDC?
Y N Central plant
DDC?
Y NCentral plant
DDC?
Y N
Do not try DR
at this time
Figure 2. HVAC DR strategy decision tree
BuildingHVACtypes
Building HVAC types are characterized using the following four primary system
attributesand the secondaryattributes listed inTable2.Theprimaryattributes are (1)
constant air volume (CAV) or variable air volume (VAV), and (2) central plant with
chilled water system or packaged units. Applicable DR strategies depend on these
system types. Applicability based on these attributes is described in each strategy
section.Manyofthe lesscommonHVACsystems, includingwatersourceheatpumps
andgascoolingsystems,arenotincludedinthisstudy.
Table 2. Bui lding HVAC typesType Primarysystemattribute Secondarysystemattribute
TypeACAVsystemwithcentralplant(CAVCentral)
Singlezone/multizoneSingleduct/dualductWithreheat/withoutreheatTypeofchiller
TypeBVAVsystemwithcentralplant(VAVCentral)
Singleduct/dualductWithreheat/withoutreheatTypeofchiller
TypeCCAVsystemwithpackageunits(CAVPackage)
Singlezone/multizoneSingleduct/dualductWithreheat/withoutreheat
TypeD
VAVsystemwithpackageunits(VAVPackage) Singleduct/dualductWithreheat/withoutreheat
CAV:Constantairvolume VAV:Variableairvolume
8/13/2019 Intro. to Commercial Building Control Strategies
25/76
12
Table3provides shortdefinitionsofDR strategies and theirapplicabilitybybuilding
HVAC type.Onecan findabuildingHVAC type that is theclosest toonesbuilding,
andlookforthosestrategiesthatareappropriate.EveniftheHVACtypematches,the
strategieslistedheremayormaynotbefeasible,dependingonthecontrolattributesof
yourbuilding.
Table 3. HVAC demand response strategies
Category
DRStrategy
Definition
A
B
C
D
Globaltemperature
adjustment
Increasezonetemperaturesetpointsforan
entirefacilityX X X X
Zone
control Passivethermal
massstorage
Decreasezonetemperaturesetpointspriorto
DRoperationtostorecoolingenergyinthe
buildingmass, andincreasezonesetpointsto
unloadfanandcoolingsystemduringDR.
X X X X
Ductstaticpressure
decrease
Decreaseductstaticpressuresetpointsto
reducefanpower.X X
Fanvariable
frequencydrivelimit
Limitordecreasefanvariablefrequencydrivespeedsorinletguidevanepositionsto
reducefanpower.
X X
Supplyair
temperatureincrease
IncreaseSATsetpointstoreducecooling
load.X X X X
Fanquantity
reduction
Shutoffsomeofmultiplefansorpackage
unitstoreducefanandcoolingloads.X X X X
Air
distribution
CoolingvalvelimitLimitorreducecoolingvalvepositionsto
reducecoolingloads.X X
Chilledwater
temperatureincrease
Increasechilledwatertemperaturetoimprovechillerefficiencyandreducecooling
load.
X X
Chillerdemandlimit Limitorreducechillerdemandorcapacity. X X
Central
plant
Chillerquantity
ReductionShutoffsomeofmultiplechillerunits. X X * *
SlowrecoverySlowlyrestoreHVACcontrolparameters
modifiedbyDRstrategies.** ** ** **
Sequential
equipmentrecovery
RestoreHVACcontroltoequipment
sequentiallywithinacertaintimeinterval. **
**
** **
Rebound
avoidance
ExtendedDRcontrol
Period
ExtendDRcontrolperioduntilafterthe
occupancyperiod.** ** ** **
*Thestrategycanbeappliedtopackagesystemsbyreducingshuttingoffsomeofthecompressors.
**ApplicabilityofreboundavoidancestrategiesisdeterminedbytheDRstrategiesselected.
ZonecontrolstrategiesGlobalTemperatureAdjustment
This strategy requires zone level direct digital control (DDC) that can be easily
programmedtorespondgloballytodemandresponsecommands.Somecontrolsystem
manufacturersprovideproducts thatenable thezonesetpointsofall thermostats tobe
changed globally by one parameter. This software feature is known as global
temperatureadjustment(GTA).ForcontrolsystemsthatdonotofferGTAasastandard
feature,itcanusuallybeprogrammedduringtheinstallationorretrofitprocess,atacost
8/13/2019 Intro. to Commercial Building Control Strategies
26/76
13
somewhathigher than if itwereastandard feature.Thisstrategyhasproven tobean
effectiveandminimallydisruptivetechniqueforachievingHVACdemandresponse.
Airdistributionstrategies
Insystemsforwhichglobaltemperatureadjustmentofzones isnotanoption(suchas
those that are not DDC), strategies that make temporary adjustments to the air
distributionormechanicalcoolingsystemscanbeemployedtoenabledemandresponse.
IftheHVAC(fans,chillers,orboth)isaconstantvolumesystem(withoutVAV),direct
controloftheequipmentmaybeconsidered.
If the HVAC system is VAV, a combination of multiple parameter controls canbe
considered.Within a closed loop system, fansand chillers always try tomaintain the
required set points by changing HVAC parameters. For example, a supply air
temperature(SAT)increasemightreducechilledwaterflowtosavecoolingenergy,but
fanpowermightrisetoincreaseairflowtomaintaincoolingzonesetpointsattheVAV
boxes
(which
try
to
compensate
for
warmer
supply
air
by
supplying
more
air).
To
achieve a demand reduction, the fan and chiller control strategies may require
simultaneous modifications. One may want to limit or fix the chilled water supply
temperature, and simultaneously limit or fix the variable frequency drive (VFD)
percentagetoreducefanpower.
While effective in achieving load reductions, the use of systemic adjustments to air
distribution systems and/or mechanical cooling systems for DR purposes has some
fundamental drawbacks. In these strategies, the DR burden is not shared evenly
between all the zones. Centralized systemic HVAC DR shed strategies can allowsubstantialdeviations in temperature,airflow,andventilationrates insomeareasofa
facility.Centralizedsystemicchanges to theairdistributionsystemand/ormechanical
cooling systems allow zones with low demand or those that are closer to the main
supply fan to continue to operate normally and hence these zones do not contribute
towardloadreductioninthefacility.Zoneswithhighdemand,suchasthesunnysideof
thebuildingorzonesattheendsoflongductruns,canbecomestarvedforair.Aftera
VAV box is fully opened, its zone setpoint is no longer under control. Increased
monitoringof
occupied
areas
should
be
conducted
when
using
these
strategies.
Coolingstrategies
Most modern centrifugal, screw, and reciprocating chillers have the capability of
reducing theirpowerdemands.This canbedoneby raising the chilled water supply
temperature setpoint orby limiting the speed, capacity, number of stages, or current
drawofthechiller.Thenumberofchillersrunningcanalsobereducedinsomeplants.
As mentioned above, reducing the central plant load can typically achieve larger
demand savings than canbe achievedby reducing the air distribution load. These
strategiesmaycausesomeairdistributionload increases,whichareusuallymorethan
compensatedforbycentralplantloadreductions.
8/13/2019 Intro. to Commercial Building Control Strategies
27/76
14
Reboundavoidancestrategies
As mentioned in section 1.7, HVAC systems tend to experience rebound, using extra
energy following DR events in order tobring systemsback to normal conditions. To
minimize the chance of high demand charges and to reduce negative effects on the
electric grid, rebound shouldbe minimized through use of a gradual return to the
normalstrategy.ThesimplestcaseiswheretheDReventendsorcanbepostponeduntil
thebuildingisunoccupied.Ifthisisnotpossible,strategiesthatallowHVACequipmentto slowly rampup or otherwise limit power usage during the return to normal state
shouldbeused.
2.2. Lighting Systems
Onahotsummerdaywhendaylight isabundant,daylitand/oroverlitbuildingsare
thebest candidates for demand reduction using the lighting system. Since lighting
producesheat,reducinglightinglevelswillalsoreducethecoolingloadwithinthespace
and allow the HVAC strategies to work for extended periods of time. Research has
shownthateachkWhoflightingsavingscanalsoprovideadditionalcoolingsavingsby
reducing the cooling load. This savings varies in quantity by building type and
characteristics,climatezone,andseasonoftheyear.AnLBNLstudyestimatedthat,ona
nationalannualaverage,1kWh lightingsavings induces0.48kWhcoolingsavings for
existingcommercialbuildings(SezgenandKoomey1998).
Lightingdemandshedstrategies tend tobesimpleanddependwidelyonwiringand
controlsinfrastructures.However,sincelightingistypicallyassociatedwithhealthand
safetyandtheshedstrategiestendtobevisible,theyhavetobecarriedoutselectively
andcarefullyconsideringthetasksperfomedinthespaceandramificationsofreduced
lightingfortheoccupants.Typically,theresolutionoflightingcontrolstendstobelower
thanthatofHVACcontrols.Also,lightingsystemsareoftennotautomatedwithEMCS.
These issuescanbemajorobstacles forautomationof lightingDRstrategies,although
lightingstrategiesarepopularlyusedinmanualDR.
Estimating the demand savings potential of lighting strategies depend on how the
demandsavings
are
achieved.
Demand
response
control
capability
of
lighting
systems
is
generallydeterminedbythecharacteristicsoflightingcircuitandcontrolsystem.There
are two ways to implement demand response control with lighting, absolute reduction
and relative reduction. Absolute reduction is achievedby programmingpreset lighting
level for times when demand response is required. This maybe configured in many
differentwaysbasedonthelightingcontrolstrategies,i.e.halfthefixtureson,onethird
ofthelampsineachfixtureon,oralllampsat70%offulllightoutput.
Theproblemwithanabsolutereductionapproachisthatitdoesnotyieldanysavingsor
mayevenincreaselightingelectricityconsumptionifthelightinglevelsarethesameasor lower than the preset levels at the time demand response is initiated. Therefore,
althoughthisapproach iseasyto implementwithcurrent lightingcontrolsystems,the
demandsavingsestimatevariesdependingonthebuildinguseandoccupancy.
8/13/2019 Intro. to Commercial Building Control Strategies
28/76
15
Relativereductionmeansreducingloadswithrespecttotheleveloflightingatthetime
ofdemand response. Insteadof reducing toapreset level,acertainpercent reduction
over the current value is achieved during a demand response event. Implementation
requires that the light output from the lamp or power output from the ballast is
communicatedback to the lighting control system, so central closed loop control is
required.Systemswithsuchsophisticatedcontrolstendtobenewerandmoreexpensive.
The
decision
to
implement
absolute
or
relative
lighting
reduction
depends
on
the
buildinglightinginfrastructure,thelightinguse inthebuilding,andthecapabilitiesof
theinstalledlightingcontrolsystem.
FollowingisalistoflightingDRstrategiesinincreasingorderofsophistication.
Zoneswitching
Fixtureswitching
Lampswitching
Steppeddimming
Continuousdimming
START
Central lighting
control?
Y NCentral lighting
control?
Y N
Dimmable
ballast?
Y NDimmable
ballast?
Y N
Zone
switching
Zone
switching?
Y NZone
switching?
Y N
Bi-level
switching?
Y NBi-level
switching?
Y N
Do not try DR
at this time
Fixture
switching
Continuous
dimming
Lamp
switching
Stepped
dimming
Bi-level
infrastructure?
Y NBi-level
infrastructure?
Y N
Step dimming
capability?
Y NStep dimming
capability?
Y N
Figure 3. Light ing DR strategy decision tree
Figure 3 presents a decision tree to assist in strategy development. Each strategy isdescribedindetailinsection3below.
Controlstrategyplanningprocedure
While the decision tree in Figure 3 shows the decision process, within a facility it is
common to find various vintage of equipment and control systems for lighting, as
retrofits tend to happen in stages depending on the varying tasks and their lightingrequirementswithinthespaces.Itisimportanttostartwiththereflectedceilingplanof
a facility tounderstand the zones, circuits, and control infrastructures. Granularityof
controlsdescribeshowmuchfloorareaiscoveredbyagivencontrolparametersuchas
8/13/2019 Intro. to Commercial Building Control Strategies
29/76
16
a photosensor. Less granular strategies affect more occupants and tend tobe more
disruptive. More granular strategies require welldesigned and wellimplemented
infrastructuresandallowoccupantstobetteracceptDRstrategyimplementation.
2.3. Miscellaneous Equipment
DR can target other equipment besides HVAC and lighting. If the equipment is
independentfromanycriticaloperation,thesequenceofcontroldoesnotrequiresuchcareful consideration. One issue of shedding miscellaneous equipment is that this
equipment is often not connected to the EMCSbut rather isoperated standalone. In
commercialbuildings,thedemandresponsepotentialofmiscellaneousequipmentshed
is usually insignificant compared to HVAC or lighting shed. On the other hand, in
industrialsites,significantdemandreductioncanbeachievedbytemporallyunloading
processloadswithoutjeopardizingtheprocessorproductquality
2.4. Non-Component-Specific Control Strategies
The demand response control strategies mentioned above can be controlled in a
sophisticatedmannerwiththeuseofanadvancedEMCS.CombinationofDRstrategies
are programmed in the EMCS to coordinate appropriate strategiesbased on various
conditionalparameterssuchasoutsideair temperature,wholebuildingdemand level,
orelectricitypricelevel.Thesestrategiesmayrequireahighlevelofprogrammingeffort.
2.5. Strategies Used in Case Studies
Table4andTable5summarizetheDRstrategiesusedduring4yearsintheLBNLAuto
DRstudiesand theothercasestudies.The listcontains56participants(35commercial
and 9 industrialbuildings). All 40 LBNL project sites implemented the strategies as
fullyautomatedDR,whiletheothercasestudiesusedeithermanualorsemiautomated
DR.
8/13/2019 Intro. to Commercial Building Control Strategies
30/76
17
Table 4. DR strategies used in LBNL Auto-DR studies (fully-automated)
Building use 20
03
20
04
20
05
20
06
Globaltemp.adjustment
Du
ctstaticpres.
Increase
SA
TIncrease
Fa
nVFDlimit
CH
Wt
emp.
Increase
Fa
nqty.reduction
Pre-cooling
Co
olingvalvelimit
Bo
ilerlockout
Fa
n-coilunitoff
Electrichumidifieroff
Ch
illerdemandlimit
Slowrecovery
Ex
tendedshedperiod
Co
mmonarealightdim
Officearealightdim
Tu
rnofflight
Dimmableballast
Bi-levelswitching
An
ti-sweatheatershed
Fo
untainpumpoff
No
n-criticalprocessshed
Office X
Office X
Office X X
Office X
Office X X X X X
Office X X X X X
Office X X
Office X X
Office X
Office X X
Hi-tech office X X X X X X X X
Hi-tech office X
Office, data center X X X X X
Office, data center X X
Office, lab X X X X X X
Office, lab X X X X X X X
Office, lab X X
Office, lab X X
Research facility X X
Cafeteria, auditorium X
Archive storage X
Library X X X
Highschool X X
Junior Highschool X X
Detention facility X
Retail X X X X
Retail X X
Retail X X
Retail X X
Furniture retail X
Furniture retail X
Supermarket X X X
Supermarket X
Supermarket X
Supermarket X
Museum X X
Distribution center X X
Manufacture, office X X
Bakery X
Material process X
Participation HVAC Lighting Other
*Somesitesparticipatedin2003or2004studystoppedduetoineligibilitytoparticipateinCPP.
*IntheParticipationcolumn, indicatestheyearofparticipation,andindicatesthatthesite
wasintheprocessofdevelopingtheDRstrategiesindicatedincolumnstotheright.
8/13/2019 Intro. to Commercial Building Control Strategies
31/76
18
Table 5. DR strategies used in case studies (manual or semi-automated)
Building useRerefenced
studies Globaltemp.adjustment
Duct
staticpres.Increase
SAT
Increase
FanVFDlimit
CHW
temp.Increase
Fanqty.reduction
Pre-cooling
Fan-coilunitoff
Chillerdemandlimit
Chillerqty.reduction
Commonarealightdim
Officearealightdim
Turn
offlight
Dimm
ableballast
Bi-levelswitching
Non-
criticalprocessshed
Elevatorcycling
Shut
offcoldstorage
Wwa
terpumppeakshift
Office Quantum X X X
Office Quantum X X X X X X X
Food process Quantum X X X
Glass process Quantum X
Chemical repackage Quantum X X X
Packing & cold storage Quantum X X X X
Packing & cold storage Quantum X X
Retail NYSERDA X X
Cement process NYSERDA X
Office NYSERDA X X X
Irrigation NYSERDA X
Lumber process SCE X
Office SCE X X
Office DOE Project X X X X X X X X
Library ISO New England X X
HVAC Lighting Other
Figure4illustratesthenumberofsitesforeachstrategyused.Themostpopularstrategy
usedwasglobal temperatureadjustment,ofwhichnearlyhalfof the listed sitesused.
DuctstaticpressureincreaseandSATincreasewerethesecondmostpopularstrategies.
0 5 10 15 20 25
Global temp. adjustment
Duct static pres. Increase
SAT Increase
Fan VFD limit
CHW temp. Increase
Fan qty. reduction
Pre-cooling
Cooling valve lim it
Turn off light
Dimmable ballast
Bi-level switching
# of sites
Fully-Automated Manual or Semi-Automated
Figure 4. Frequency of DR strategies
8/13/2019 Intro. to Commercial Building Control Strategies
32/76
19
3. Demand Response Strategy Detail
Thissectiondescribesthedetailsofthesystemoperationmethodsofdemandresponse
strategies.Eachstrategy isexplainedwithsystemrequirements,sequenceofoperation
andspecific issues toconsider.The information is firstsummarized in table formand
thenexplainedbelow.
3.1. HVAC Systems
ThissectiondescribesthedetailsofHVACDRcontrolstrategies.Table6throughTable
15summarizethekeyinformationonthestrategy,andthedetailsareexplainedbelow
thetable. Definitionsofitemsinthetablearelistedbelow,
DefinitionBriefdefinitionoftheDRcontrolstrategy.
HVACtypeApplicableHVACtypesasdefinedinTable2.
Target loads HVAC system component or equipment whose electric load is
targetedtobereducedbytheDRstrategy.
Category DR approach: demand shed, demand shift, or demand limit as
definedinSection1.6.
System applicabilityHVACorcontrolsystemcharacteristicsrequired touse
theDRstrategy.
Sequence
of
operation
Detailed
sequence
of
operation
used
to
program
the
EMCStoimplementtheDRcontrolstrategy.
EE potentialPotentialofachievingsavings fromenergyefficiencyaswellas
DRbyapplyingtheDRstrategyduringregularpracticeoutsideofDRevents.
ReboundRiskof reboundpeakandnecessityof reboundavoidancestrategy
fromapplyingtheDRstrategy.
Cautions Miscellaneous issues to be considered when the DR strategy is
appliedto
mitigate
and
avoid
any
risks.
Applied sites Number andbuilding type of the LBNL AutoDR participant
sites that applied the DR strategy. None indicates the DR strategy was not
implemented at the LBNL AutoDR sites, but was used in some other case
studiesoratan excandidate site that implemented the strategybut couldnot
automateit.
8/13/2019 Intro. to Commercial Building Control Strategies
33/76
20
3.1.1. Global temperature adjustment
Table 6. Condi tions for g lobal temperature adjustment (GTA)
Definition Increasezonetemperaturesetpointsforanentirefacility.
HVACtype All
Targetloads Airdistribution,cooling
Category
Demandshed
System
applicability
1.DDCzonecontrol
2a.Globaltemperatureadjustment(GTA)capabilityatzonelevel,or
2b.CapabilitytoprogramGTAateachVAVbox.
Option1:Absolutesetpointadjustment
Globallyadjust(increase)allzonecoolingsetpointstoacommon
value(e.g.76F),TcF
Globallyadjust(decrease)orleaveunchangedallzoneheating
setpointstoacommonvalue(e.g.68F),ThF
(Tc:DRmodecoolingsetpoint,Th:DRmodeheatingsetpoint)Sequenceof
operationOption2:Relativesetpointadjustment
Globallyadjust(increase)allzonecoolingsetpointsbyacommon
differentialtemperaturefromtheirpriorsetpoint(e.g.2F),TcF
Globallyadjust(decrease)orleaveunchangedallzoneheating
setpointsbyacommondifferentialtemperaturefromtheirprior
setpoint(e.g.2F),ThF
(Tc:DRmodecoolingsetpoint,Th:DRmodeheatingsetpoint)
EEpotentialSomeoccupantsmaybemorecomfortableduringDRevents. This
wouldindicatemakingpermanentchangestothesetpoints.
Rebound Reboundavoidancestrategyrequired.
CautionsAdjustzonetemperaturesetpointsinmultiplestepsifalongshed
durationisrequired.
Appliedsites
15officebuildings,6retailstores,2laboratoryfacilities,2schools,
1manufacturingfacility,1museum,1archivestorage,1detention
facility
Global Temperature Adjustment (GTA) of occupied zones is a strategy that allows
commercialbuildingoperators toeasily adjust the space temperature setpoints for an
entirefacilitybyonecommandfromonelocation.Typically,thisisdonefromascreen
onthehumanmachineinterface(HMI)totheEMCS.Infieldtests,GTAwasshowntobe
the most effective and least objectionable strategy of the HVAC DR strategies tested
(Pietteetal.2005a,2005b,and2006).Itismosteffectivebecauseitreducestheloadofall
associatedairhandlingandcoolingequipment.Itisleastobjectionablebecauseitshares
the
burden
of
reduced
service
level
evenly
between
all
zones.
GTA
based
DR
strategies
can be implemented either automatically based on remote signals or manually by
buildingoperators.
8/13/2019 Intro. to Commercial Building Control Strategies
34/76
8/13/2019 Intro. to Commercial Building Control Strategies
35/76
22
thesevendorsprovidedsomeofthelargestshedsandrequiredtheleastamountofset
uplabor.
For sites that have EMCS controlled space temperature zones,but lack GTA, it can
typically be added in the field. To add GTA to an existing site, each EMCS zone
controllermustbeprogrammedtolistenforaglobalGTAcommandfromthecentral
EMCS system. In addition, the central system must be programmed to send GTA
commandstoallrelevantzonecontrollersontheEMCSdigitalnetwork.TypicallyGTAcommandsaresentinaglobalbroadcasttoallcontrollerssimultaneously.
Manufacturersofferdifferent typesofVAVzone setpointconfigurationmethods.The
followingtwoexamplesarecommonVAVzonesetpointconfigurations.
1. Definezonecoolingsetpointsandzoneheatingsetpointsseparately.
2. Definethemidpointbetweenzonecoolingsetpointsandzoneheatingsetpoints
andthewidthofthedeadband.2Increasingthedeadbandmakescoolingsetpoints
higher and heating setpoints lower. Raising the midpoint makesboth coolingandheating setpointshigher.Figure 6 shows the change in thedeadband and
required airflow change in a VAV system.3 Increasing the cooling setpoints
reducestherequiredairflow.
Heating
setpoint
Cooling
setpoint
Min
CFM
AirflowCFM
Deg-FThNew
setpoint
TcNew
setpoint
Original
deadband
New deadband
ThTh TcTc
Setpoint-airflow relationship
with original deadband
Setpoint-airflow relationship
with new deadband
Figure 6. Zone setpoints deadband
2Deadband in thecontextofzone temperaturecontrolhas twodefinitions;1) the temperature
range between actuation and deactuation of the cooling or heating system, and 2) the
temperature range where no cooling or heating (beyond that required to provide freshair) is
provided.Although the firstdefinitionhasbeenhistoricallyused, theseconddefinition isalsocommonlyused.Thisreportusestheseconddefinition.
3 Figure 5 shows proportional control for illustrative purposes. Most zone controllers use
proportionalandintegralcontrolalgorithms.
8/13/2019 Intro. to Commercial Building Control Strategies
36/76
23
IfGTAofzonesisavailable,itistherecommendedHVACDRstrategyforcommercial
buildings.Infieldtests,sitesthatusedHVACDRstrategiesotherthanGTAusuallydid
sobecausethatfeaturewasnotavailableatthesite.ReasonsthatGTAwasnotavailable
include:1)Space temperaturewasnotcontrolledby theEMCS (e.g.useofpneumatic
controlsinoccupantzones),and2)SpacetemperaturewascontrolledbytheEMCS,but
thespacetemperaturecontrollersdidnotincludetheGTAfeature.
WhiletheGTAstrategyreducestheserviceleveloftheoccupiedspaces,itdoessousinga closedloop control strategy in a highly granular fashion. This causes the DR shed
burden tobeevenlysharedbetweenallbuildingoccupantsandkeepsallzonesunder
control.Sincenoneof thezonesare starved forairflow, there isno riskofventilation
ratesdroppingbelowspecifieddesignlevels.
SometimesiftheHVACsystemsareoversizedandthechillersarenotcontrolledbythe
percentage of zones asking for cooling, the GTA strategy has tobe combined with
supplyair temperature reset.One typicalexample isabuildingwithmultiple rooftop
units,wherethecompressorsarecontrollednotbyhowmanyzonesaredirectlyaskingfor cooling, but by meeting the supply air temperature setpoints. If the units are
oversizedortheminimumsupplyairflowrateistoohigh,GTAmaynotworkandthe
zone temperatures will not follow the new setpointsbecause of the excessive cooling
providedby theminimumair flow. In thatcase, theSATsetpointhas tobe increased
about3~5oFintheGTAperiodtoreducetheminimumcoolingdeliveredbytheHVAC
system.
TheGTA strategyworkswellwithmostbuiltupHVAC systems,where typically the
chillersshutoffifthepercentageofzonesthataskforcoolingislessthanapredefined
threshold.InGTA,ifnozonesaskforcoolingoncethenewsetpointisabovethecurrent
zone temperatures, thechillersnormally shutoffautomatically.Sometimes, insteadof
being completely shut off, the chillers will onlybe reduced to a partial capacity, to
maintaincoolingforsomehotspotsthatarepoorlybalancedorotherwiseoverloaded.
Thermalzonesthatarepoorlydesignedorpoorlybalancedcanalsoposechallengesdue
to overcooling. If minimum fresh air requirements are overcooling many zones, shed
savingsfrom
aGTA
DR
strategy
alone
may
not
be
effective.
This
problem
can
be
solved
by increasing the supply air temperature in addition to raising the zone temperature
setpoints.
DemandsavingscomponentsofGTA
Demand savingsby theGTA strategy consistsof twoparts, steadystate savingsand
transientsavings. Whenzonesetpointsareraised,coolingisturnedofforreducedtoits
minimaloperationuntilzonetemperaturesreachthenewsetpoints(transientsavings).
After zone temperatures are stabilized at the new setpoints, the cooling load is still
lowerthanthebaselinecoolingloadduetoasmallerdifferencebetweenzonesetpoints
andOAT(steadystatesavings).
8/13/2019 Intro. to Commercial Building Control Strategies
37/76
24
Transient savings can be achieved by the thermal mass storage effect of building
structuremass,includingfloorslabandinteriorandexteriorwalls,furniture,andother
materials. When zone setpoints are increasedby the GTA strategy, the thermal mass
componentshave stored coolingenergy.The thermalmass coolsdown the indoorair
anddisplaces the cooling loaduntil it runsoutof stored cooling energy.Durationof
transient savings can widely vary depending on factors includingbuilding structure,
outside
air
flow
rate,
internal
heat
gain,
and
solar
heat
gain
through
windows.
Figure7 illustratesaconceptualdiagramofdemandsavings (notactual fielddata)by
theGTAstrategywithzonesetpoint(ZTsetpoint)increasefrom72Fto76F. Thezone
temperture (ZT read) is also shown. A case study of this strategy is introduced in
AppendixA,sectionA.1.
0
100
200
300
400
500
11
:00
11
:30
12
:00
12
:30
13
:00
13
:30
14
:00
14
:30
15
:00
15
:30
16
:00
16
:30
17
:00
17
:30
18
:00
18
:30
19
:00
Time
WholeBuildingPower[kW]
70
75
80
85
90
95
Temperature[F]
Baseline DR demand ZT SP ZT read
Transient Savings
Steady-State Savings
Figure 7. Conceptual d iagram of demand savings for typical HVAC-based demand
response strategy
8/13/2019 Intro. to Commercial Building Control Strategies
38/76
25
3.1.2. Passive thermal mass storage
Table 7. Conditions for passive thermal mass storage
DefinitionDecreasezonetemperaturesetpointsduringoffpeakhourspriortoacurtailmentto
storecoolingenergyinthebuildingmass,andthenincreasezonesetpointstounload
fanandcoolingsystemduringacurtailment.
HVACtype All
Targetloads Airdistribution,cooling
Category
Demandshiftordemandshed
System
applicability
1.DDCzonecontrol
2a.Globaltemperatureadjustment(GTA)capabilityatzonelevel,or
2b.CapabilitytoprogramGTAateachVAVbox.
3.Mediumtohighbuildingmass.
Sequenceof
operation
DecreasezonetemperaturesetpointsbyTc1Fpriortoacurtailment.
IncreasezonetemperaturesetpointsbyTc2Fduringacurtailment.
EEpotentialOccasionallyproducestotalenergyusagesavingsinmildclimates,especiallywhen
nighttimefreeventilationcoolingisused. However,totalenergyusagemayincrease
dependingonclimate,buildingtype,andprecoolingschedule.Rebound Reboundavoidancestrategyrequired.
Cautions
ThisstrategyisapplicabletodayaheadDRprograms,wheretheeventnotificationis
sentonthedaybefore. Iftheeventnotificationisonthesameday,thereisnot
sufficienttimetostoreenoughcoolingenergy. Thepassivethermalmassstorage
controlisverycomplicatedandhastobedoneproperly. Testing,adjusting,and
balancingcontrolschedulesarerecommendedinthepreparationphase.Avoidover
coolingduringtheprecoolingperiodtopreventcoldcomplaintsfromoccupants.
Appliedsites 1officebuilding,1museum
Precooling the thermalmassof thebuildingcanbeused toreduce thepeak load.Forexample,insummer,thebuildingmasscanbecooledduringnonpeakhourstoreduce
thecoolingloadinthepeakhours.Asaresult,thecoolingloadisshiftedintimeandthe
peak demand is reduced. Thebuilding mass canbe cooled most effectively during
unoccupiedhoursbecauseitispossibletorelaxthecomfortconstraints.
Thermalmasscontrolstrategiesdiffer in theway theystoreandreleaseheat from the
mass.Thebuildingmassmaybecooledbynaturalormechanicalventilation,withor
withoutmechanicalcooling.Precoolingcanbeperformedeitherduringtheunoccupied
hoursorduringtheoccupiednonpeakhours,usuallyinthemorning.Inclimateswitha
large diurnal temperature swing, it may be possible to precool the building mass
withoutmechanicalcooling.
Ifthereissufficientprecoolingandthedaytimecoolingloadisrelativelylow,itmaybe
possible for the indoorair temperature toremainwithin thecomfortrangeduring the
peakhourswithoutanymechanicalcooling.Coolingenergystored inthemasscanbe
dischargedduringthepeakhoursbyeitherzonaltemperatureresetordemandlimiting
thecooling
plant
and
distribution
system
(Xu
2004).
Adetailed
simulation
study
of
the
passivethermalmassstoragestrategyissummarizedinAppendixA,sectionA.2(Braun
etal.2001).
8/13/2019 Intro. to Commercial Building Control Strategies
39/76
26
3.1.3. Duct static pressure decrease
Table 8. Conditions for duct static pressure decrease
Definition Decreaseductstaticpressure(DSP)setpointstoreducefanpower.
HVACtype B(VAVCentral),D(VAVPackage)
Targetloads Airdistribution,cooling(occasionally)
Category Demandshed
System
applicability
1.AllzonecontrolsystemsincludingpneumaticandDDC
2.DDCforairhandlingunit
Sequenceof
operationLowerDSPsetpointsbyX%.
EEpotentialTuningDSPsetpointscansavefanpowerconsistentlywithouta