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3.1.10 Systems Simulation

General

The Rating Software shall be capable of modeling:

  • The baseline building systems defined in Chapter 6,
  • The lighting, water heating, HVAC and miscellaneous equipment detailed in Chapter 6
  • All compulsory and required features as listed in Appendix A and detailed in Chapter 6
  • The capability to model multiple zone systems serving at least 15 thermal blocks.

The Rating Software shall be capable of modeling plenum air return.

Terminal Characteristics

The Rating Software shall be capable of simulating the effect on space temperature and energy use of:

  • Limited capacity of terminal heating devices;
  • Limited capacity of terminal cooling devices; and
  • Limited rate of air flow to thermal blocks.

HVAC Systems and Equipment

The Rating Software shall be capable of simulating the effect on energy use and space temperature in thermal blocks served by the HVAC system, including:

  • Limited heating capacity of an HVAC system;
  • Limited cooling capacity of an HVAC system;
  • Temperature rise of supply air due to heat from supply fan, depending on the location of the fan;
  • Temperature rise of return air due to heat from return fan;
  • Temperature rise of return air due to heat from lights to return air stream; and
  • Fan power as a function of supply air flow in variable air volume systems.

Central Plant Systems and Equipment

The Rating Software shall be capable of simulating the effect on energy use of limited heating or cooling capacity of the central plant system.

If the Rating Software is not capable of simulating the effect of limited heating or cooling capacity of the central plant system on space temperature in thermal blocks dependent on the central plant system for heating and cooling, then it shall issue a warning message when loads on the central plant system are not met.

Equipment Performance Curves

The Rating Software shall be capable of modeling the part load efficiency and variation in capacity of equipment as follows:

  • Furnaces as a function of part load;
  • Boilers as a function of part load, supply hot water temperature, and return hot water temperature;
  • Water-cooled compressors including heat pumps and chillers as a function of part load, evaporator fluid, or air temperature and condensing fluid temperature;
  • Air-cooled compressors including heat pumps, direct expansion cooling and chillers as a function of part load, ambient dry-bulb temperature, and wet-bulb temperature returning to the cooling coil;
  • Evaporative cooling systems as a function of ambient wet-bulb temperature; and
  • Cooling towers as a function of range, approach and ambient wet-bulb temperature.

Economizer Control

The Rating Software shall be capable of modeling integrated air- and water-side economizers.

The Rating Software shall be capable of modeling electronic enthalpy air-side economizer controls that vary the high limit as a function of both temperature and enthalpy.

Air Side Heat-Recovery

The Rating Software shall be capable of modeling heat recovery between the exhaust air stream and the outside air stream. The software shall account for auxiliary energy uses associated with heat recovery systems, including pumping energy, frost control, and system control.

Heat-Recovery Water Heating

The Rating Software shall be capable of modeling heat recovery water heating from the following sources:

  • Double bundled chiller;
  • Refrigerant desuperheater as part of a packaged HVAC unit;
  • Heat exchanger on the condenser water loop; and
  • Heat-recovery water-to-water heat pump operating off of the condenser or chilled water loop.

Heat-Pump Water Heaters

The Rating Software shall be capable of modeling heat-pump water heaters. The algorithm must allow the evaporator coil to be located in:

  • Any thermal block;
  • Any plenum; and
  • Outside.