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Green Star Reference Building HVAC Systems for EnergyPlus

Based on Table 62, 63, and 64 from the Energy Use Calculation Guide, here is a comprehensive definition of Reference Building HVAC systems translated into EnergyPlus objects and parameters.

Overview: System Type Selection

Project Type
System Type
Description

Residential

1

Air-cooled split DX heat pump (one per apartment)

Residential common areas

-

Not conditioned

Non-residential < 2,300 m²

1

Air-cooled packaged reverse cycle heat pump

Non-residential > 2,300 m² and < 1,000 kWr cooling

2

VAV with reheat, air-cooled chillers

Non-residential ≥ 1,000 kWr cooling

3

VAV with reheat, water-cooled chillers

Fire Stations

1

Package/Split DX reverse cycle

System Type 1: Package/Split DX Reverse Cycle Heat Pump

System Characteristics

Parameter
Value

Fan Control

Constant Volume

Cooling

Direct Expansion

Heating

Electric Heat Pump + Direct Electric Auxiliary

EnergyPlus Objects

!----- HVAC SYSTEM TYPE 1: PACKAGED DX HEAT PUMP -----

!----- Zone HVAC Equipment -----
ZoneHVAC:PackagedTerminalHeatPump,
    <Zone Name> PTHP,          !- Name
    <Availability Schedule>,    !- Availability Schedule Name
    <Zone Name> PTHP Air Inlet, !- Air Inlet Node Name
    <Zone Name> PTHP Air Outlet,!- Air Outlet Node Name
    OutdoorAir:Mixer,          !- Outdoor Air Mixer Object Type
    <Zone Name> OA Mixer,      !- Outdoor Air Mixer Name
    <Design Supply Air Flow>,  !- Cooling Supply Air Flow Rate {m3/s}
    <Design Supply Air Flow>,  !- Heating Supply Air Flow Rate {m3/s}
    <Outdoor Air Flow Rate>,   !- No Load Supply Air Flow Rate {m3/s}
    <Outdoor Air Flow Rate>,   !- Cooling Outdoor Air Flow Rate {m3/s}
    <Outdoor Air Flow Rate>,   !- Heating Outdoor Air Flow Rate {m3/s}
    <Outdoor Air Flow Rate>,   !- No Load Outdoor Air Flow Rate {m3/s}
    Fan:ConstantVolume,        !- Supply Air Fan Object Type
    <Zone Name> Supply Fan,    !- Supply Air Fan Name
    Coil:Heating:DX:SingleSpeed, !- Heating Coil Object Type
    <Zone Name> DX Heating Coil, !- Heating Coil Name
    0.0,                       !- Heating Convergence Tolerance
    Coil:Cooling:DX:SingleSpeed, !- Cooling Coil Object Type
    <Zone Name> DX Cooling Coil, !- Cooling Coil Name
    0.0,                       !- Cooling Convergence Tolerance
    Coil:Heating:Electric,     !- Supplemental Heating Coil Object Type
    <Zone Name> Supp Heating Coil, !- Supplemental Heating Coil Name
    <Max Supply Air Temp>,     !- Maximum Supply Air Temperature from Supplemental Heater {C}
    21.0,                      !- Maximum Outdoor Dry-Bulb Temperature for Supplemental Heater {C}
    DrawThrough,               !- Fan Placement
    <Fan Schedule>;            !- Supply Air Fan Operating Mode Schedule Name

!----- Constant Volume Fan -----
Fan:ConstantVolume,
    <Zone Name> Supply Fan,    !- Name
    <Availability Schedule>,   !- Availability Schedule Name
    0.7,                       !- Fan Total Efficiency
    <Fan Pressure Rise>,       !- Pressure Rise {Pa}
    <Design Air Flow Rate>,    !- Maximum Flow Rate {m3/s}
    0.9,                       !- Motor Efficiency
    1.0,                       !- Motor In Airstream Fraction
    <Zone Name> Mixed Air Node,!- Air Inlet Node Name
    <Zone Name> Fan Outlet;    !- Air Outlet Node Name

!----- DX Cooling Coil -----
Coil:Cooling:DX:SingleSpeed,
    <Zone Name> DX Cooling Coil, !- Name
    <Availability Schedule>,   !- Availability Schedule Name
    <Cooling Capacity>,        !- Gross Rated Total Cooling Capacity {W}
    <Sensible Heat Ratio>,     !- Gross Rated Sensible Heat Ratio
    <EER / 3.412>,             !- Gross Rated Cooling COP {W/W}
    <Design Air Flow Rate>,    !- Rated Air Flow Rate {m3/s}
    ,                          !- 2017 Rated Evaporator Fan Power Per Volume Flow Rate
    ,                          !- 2023 Rated Evaporator Fan Power Per Volume Flow Rate
    <Coil Air Inlet Node>,     !- Air Inlet Node Name
    <Coil Air Outlet Node>,    !- Air Outlet Node Name
    <Cooling Capacity f(T) Curve>,    !- Total Cooling Capacity Function of Temperature Curve Name
    <Cooling Capacity f(FF) Curve>,   !- Total Cooling Capacity Function of Flow Fraction Curve Name
    <EIR f(T) Curve>,          !- Energy Input Ratio Function of Temperature Curve Name
    <EIR f(FF) Curve>,         !- Energy Input Ratio Function of Flow Fraction Curve Name
    <PLF Curve>;               !- Part Load Fraction Correlation Curve Name

!----- DX Heating Coil (Heat Pump) -----
Coil:Heating:DX:SingleSpeed,
    <Zone Name> DX Heating Coil, !- Name
    <Availability Schedule>,   !- Availability Schedule Name
    <Heating Capacity>,        !- Gross Rated Heating Capacity {W}
    <COP>,                     !- Gross Rated Heating COP {W/W}
    <Design Air Flow Rate>,    !- Rated Air Flow Rate {m3/s}
    ,                          !- 2017 Rated Supply Fan Power Per Volume Flow Rate
    ,                          !- 2023 Rated Supply Fan Power Per Volume Flow Rate
    <Coil Air Inlet Node>,     !- Air Inlet Node Name
    <Coil Air Outlet Node>,    !- Air Outlet Node Name
    <Heating Capacity f(T) Curve>,    !- Heating Capacity Function of Temperature Curve Name
    <Heating Capacity f(FF) Curve>,   !- Heating Capacity Function of Flow Fraction Curve Name
    <EIR f(T) Curve>,          !- Energy Input Ratio Function of Temperature Curve Name
    <EIR f(FF) Curve>,         !- Energy Input Ratio Function of Flow Fraction Curve Name
    <PLF Curve>,               !- Part Load Fraction Correlation Curve Name
    <Defrost EIR f(T) Curve>,  !- Defrost Energy Input Ratio Function of Temperature Curve Name
    -8.0,                      !- Minimum Outdoor Dry-Bulb Temperature for Compressor Operation {C}
    ,                          !- Outdoor Dry-Bulb Temperature to Turn On Compressor {C}
    5.0,                       !- Maximum Outdoor Dry-Bulb Temperature for Defrost Operation {C}
    200.0,                     !- Crankcase Heater Capacity {W}
    ,                          !- Crankcase Heater Capacity Function of Temperature Curve Name
    10.0,                      !- Maximum Outdoor Dry-Bulb Temperature for Crankcase Heater Operation {C}
    ReverseCycle,              !- Defrost Strategy
    Timed,                     !- Defrost Control
    0.058333,                  !- Defrost Time Period Fraction
    autosize;                  !- Resistive Defrost Heater Capacity {W}

!----- Supplemental Electric Heating Coil -----
Coil:Heating:Electric,
    <Zone Name> Supp Heating Coil, !- Name
    <Availability Schedule>,   !- Availability Schedule Name
    1.0,                       !- Efficiency
    <Supplemental Heating Capacity>, !- Nominal Capacity {W}
    <Coil Air Inlet Node>,     !- Air Inlet Node Name
    <Coil Air Outlet Node>;    !- Air Outlet Node Name

Key Parameters for System Type 1

Parameter
Reference Building Value
Notes

Cooling EER

Per NCC Section J clause J5.11 or MEPS

Convert to COP: COP = EER / 3.412

Heating COP

Equal to EER if only EER specified

Use AEER/ACOP if specified

Auxiliary heat activation

Outdoor temp < 4°C AND last thermostat stage

Per ASHRAE 90.1 G3.1.3.1

Fan efficiency

Per NCC J5.4(b) minimum

Based on fan type and motor power

System Type 2: VAV with Air-Cooled Chillers

System Characteristics

Parameter
Value

Fan Control

Variable Volume

Cooling

Chilled Water (Air-Cooled Chillers)

Heating

Heating Hot Water (Fossil Fuel Boiler)

EnergyPlus Objects - Air Side

EnergyPlus Objects - Chilled Water Plant (Air-Cooled)

EnergyPlus Objects - Heating Hot Water Plant

System Type 3: VAV with Water-Cooled Chillers

System Characteristics

Parameter
Value

Fan Control

Variable Volume

Cooling

Chilled Water (Water-Cooled Chillers)

Heating

Heating Hot Water (Fossil Fuel Boiler)

Key Differences from System Type 2

The air-side system is identical to System Type 2. The differences are in the chiller plant:

Key Reference Building Parameters Summary

Chiller Specifications

Parameter
Air-Cooled (Type 2)
Water-Cooled (Type 3)

Number of chillers

2

3

Sizing

55% each

45%, 45%, 15%

CHW supply temp

6.5°C

6.5°C

CHW return temp

12.5°C

12.5°C

CCW entering temp

N/A

29.5°C

CCW leaving temp

N/A

25.0°C (controlled)

Efficiency

NCC Section J or MEPS minimum

NCC Section J or MEPS minimum

Chiller Part-Load Multipliers (for IPLV)

Capacity (kWr)
75% Load
50% Load
25% Load

Air-Cooled

< 700

1.143

1.556

1.521

≥ 700

1.235

1.736

1.725

Water-Cooled

< 350

1.192

1.368

1.089

350-499

1.053

1.142

1.142

500-699

1.112

1.232

1.232

≥ 700

1.1065

1.174

1.181

Boiler Specifications

Parameter
Value

Number

2

Sizing

60% each

Fuel

Natural gas

HHW supply temp (design)

80°C

HHW return temp (design)

65°C

Efficiency

Per NCC J5.9(d) minimum

Part-load curve

Linear: 100% efficiency at full load, 70% at 15% load

Temperature Reset Schedules

Chilled Water:

Outdoor Air Temp
CHW Supply Temp

< 16°C

10.0°C

16-24°C

Linear 10.0 to 6.5°C

> 24°C

6.5°C

Heating Hot Water:

Outdoor Air Temp
HHW Supply Temp

< 8°C

80°C

8-16°C

Linear 80 to 60°C

> 16°C

60°C

VAV System Parameters

Parameter
Value

Supply air temp difference

11 K below room temp

Minimum turndown

40% of design or OA rate (whichever greater)

Fan part-load curve (Method 1)

P = 0.0013 + 0.1470×PLR + 0.9506×PLR² - 0.0998×PLR³

Economizer

Required per NCC Part J5

Cooling Tower Parameters (System Type 3)

Parameter
Value

Number

2

Sizing

50% each

Fan type

Axial, variable speed

Design leaving temp

29.5°C or 5.5K approach (whichever greater)

Design range

4.5 K

Control setpoint

20°C leaving temp

Minimum approach

3 K on wet bulb

Fan power

Per NCC J5.12(a)

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