A building must have at least one HVAC system, and every block must have an HVAC system assigned to it (either an Air Handler or Zone Equipment component). The Asset Scoring Tool will not model unconditioned spaces (spaces with no heating and no cooling), except for parking garages. Select the Heating & Cooling icon from the asset score toolbar to create or edit the equipment of the HVAC system(s) supplying your building.
Create an HVAC system
Add HVAC components to your building by selecting the Add (plus) icon from among the following available selections on the Heating and Cooling page:
HVAC system entries may be edited by selecting the blue "Edit" icon, and/or may be deleted by selecting the yellow "trash can" icon.
Note: Required fields in each of the data entry screens are indicated with a red star (*). If a non-required field is left blank, the tool will infer a value based on system type, building age, and location.
The tool uses standard equipment life to calculate the year of manufacture which influences the inference of system efficiency. The standard equipment life assumed for the different system types are listed below:
|System Type||Standard Equipment Life|
|Air Source Heat Pump||15 years|
|Packaged roof top unit||15 years|
Assign HVAC components to building blocks
After creating an HVAC system, either Air Handler or Zone Equipment components must be assigned to each of the blocks in the building. View the Assign Use Types and Components section for instructions on assigning components to buildings and blocks.
After assigning either Air Handler or Zone Equipment components to a block, click on the block to open an HVAC Systems window to view the system assignment and additional option inputs.
HVAC assigned components are referred to and are listed as 'Primary Heating/Cooling Systems', except Dedicated Outdoor Air Systems (DOAS) or Exhaust Fans which are listed as 'Ventilation Systems', or Baseboards and Radiators which are listed as ‘Secondary Heating/Cooling Systems’.
Only one HVAC system may be assigned to a block, except for DOAS, which need a Zone Equipment Primary Heating/Cooling System, and Baseboards, Radiators and Exhaust Fans, which must be paired with a Primary Heating/Cooling System to complete an HVAC system entry.
Thermal Zone Layout
A thermal zone is an air volume at uniform temperature plus all the heat transfer and heat storage surfaces bounding or inside of that air volume. It is not a geometric concept. Zone Layout refers to how the building is divided into thermal zones. Thermal zones are a fundamental part of building energy simulation and can be thought of as rooms or collections of rooms inside the building that have similar thermal loads, share a common thermostat, or are served by the same HVAC system.
Energy Asset Score Data Entry Options for Thermal Zone Layout
Thermal Zone Layout – Pull-down menu selections:
I don't know – If selected, the thermal zone layout will be set to single zone by default.
Single Zone – The floor is an open space served by a single HVAC system; this option is typically used for smaller buildings.
Perimeter and Core – The floor is divided into four perimeter zones and one core zone; this option is typically used for larger buildings or for buildings with varying loads in perimeter versus core spaces. For a perimeter and core layout, specify the Perimeter Zone Depth.
Perimeter Zone Depth – Menu item available if perimeter and core selected as the thermal zone layout type. Enter a value in feet per the layout in the following Thermal Zone Layout figure:
Note: Enter Single zone for the Thermal Zone Layout if width in a block is less than 2.5 times the perimeter zone depth.
Other HVAC System Data Entry Options
Secondary Heating Fraction – Available input if a Secondary Heating/Cooling System (Baseboard or Radiator) has been assigned to a block. A value of 1.0 will be visible if the Primary Heating/Cooling System is a Window Air Conditioner. A default value of 0.2 will be visible and editable if the Primary Heating/Cooling System is a PTAC or FPFCU. Enter a value less than or equal to 1.0 for the fraction of heat served by the selected baseboard system.
CO Sensors – Check box Menu item available if either of the Parking Garage use types are selected as the building use type. Select if Carbon Monoxide (CO) sensors designed for exhaust fan control in parking garages are installed and in use. CO levels in parking garages must be controlled or ventilated when concentrations approach unsafe levels. Automatic CO sensing devices may be employed to modulate the ventilation system to maintain safe CO concentrations.
Note: Parking garages are typically not heated or cooled. Select "No Heating" and "No Cooling" for Parking Garage (Ventilation Only) use types.
Percent Area DCV Control – Available input if Demand Control Ventilation has been checked for an Air Handler, and if either of the ‘Advanced System Parameters’ or ‘Generate a verified Total HVAC System Performance Ratio’ boxes are checked in Settings. Enter a value from 1-100 to represent the percentage of total area ventilated by the DCV in the block.