hVac controls guide for Plans examiners and Building inspectors

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Performance PathMany building energy codes allow buildings to satisfy the code requirements either by meeting each specificrequirement or by demonstrating that the building performs as well or better than a reference buildingdesign that satisfies the specific requirements. Both ASHRAE 90.1 and the IECC offer a performance pathto compliance. However, even buildings following the performance path must meet some mandatoryrequirements relating to HVAC controls.Thermostatic control of heating and cooling and control of ventilation are required for all buildings; as aresome controls relating to supplemental heaters in heat pumps, humidity and commissioning. These nearlyuniversal requirements are discussed in the following section on control requirements for all systems. Latersections turn to requirements that may not be satisfied by buildings taking the performance path.10 Performance Path
Control Requirements for All SystemsThermostatic Control of Heating and CoolingThermostatic controls are required in each conditioned building zone. These devices must be capable ofsetting the zone’s target temperature for heating and cooling. They must also prevent simultaneous heatingand cooling of the zone and allow for a range of allowable temperatures, known as a deadband, in whichneither heating nor cooling is provided. Finally, the thermostatic controls must allow the system to scheduleunoccupied periods and occupied periods, allowing for a system start up period between. During theunoccupied period, heating and cooling target temperatures can be set back to conserve energy by allowing agreater range of space temperatures.Plan ReviewSuggested Compliance Check(s):• Check mechanical floor plans to verify that there is at least onethermostat per distinct occupancy area (figure 1).• Review the mechanical floor plans and mechanical schedule to locate control sequences and verifythat the design engineer has specified deadband, set back and scheduling capabilities (figures 2-4).** If the building is equipped with a building automation system (BAS), then these capabilities will most likely beprovided by the BAS. The BAS specifications or manual should indicate that the required capabilities are present.Control Requirements for All Systems 11
Page 2 and 3: ContentsIntroduction ..............
Page 5 and 6: Commercial buildingControl requirem
Page 7 and 8: Prescriptive requirementsfor Comple
Page 9: Code Requirements andCompliance Che
Page 13 and 14: Figure 4: Sample control sequence s
Page 15 and 16: d) Automatic setback and shutdown c
Page 17 and 18: Figure 9: VSD installed on a supply
Page 19 and 20: Figure 13: Motorized damperFigure 1
Page 21 and 22: Building InspectionSuggested Compli
Page 23 and 24: 4) The supply of outside air is red
Page 25 and 26: ) Control strategyEconomizers must
Page 27 and 28: 4) The supply of outside air is red
Page 29 and 30: must be positioned well down the du
Page 31 and 32: Figure 23: BAS screen shot indicati
Page 33 and 34: Code SectionsIECCASHRAE2009: NA 200
Page 35 and 36: Figure 27: Illustrated control sequ
Page 37 and 38: Code SectionsIECCASHRAE2009: 503.4.
Page 39: Building InspectionSuggested Compli
Page 42 and 43: Building InspectionSuggested Compli
Page 44 and 45: Figure 38: Sample control sequence
Page 46: Building Technology ProgramThe U.S.

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