ECM parameters
Every parameter in the ECM Explorer and the Existing Building Parameters panel, by tab.
On this page
How to read a row
Each row has up to three buttons:
- Existing (gray) - Your building as calibrated.
- Energy Code (blue) - What the selected energy code requires. Shown only where the code sets a value.
- Customized (light blue) - The value you set. Select it, then move the slider.
Sliders that improve a building only go one way. For example, the roof R-value slider runs from the existing value up, and the lighting power slider from the existing value down. Values are shown with one decimal place.
A parameter appears only when it applies to your building’s systems. The conditions are listed in each table. If the building has a second HVAC zone, the Operations and Air-side tabs are split into (Main) and (Sub).
Envelope
The external walls, windows, roof and floor of the building. The info icon next to the heading shows the window-to-wall ratio (WWR).
| Parameter | What it is | Unit or options |
|---|---|---|
| Roof | Effective R-value of the roof insulation | ft²·h·°F/Btu, up to 60 |
| Exterior Walls | Effective R-value of the wall insulation | ft²·h·°F/Btu, up to 25 |
| Windows | Assembly U-value | Btu/h·ft²·°F, down to 0.1 |
| Window SC-value | Shading coefficient of the windows | down to 0.1 |
| Window Film | Add window film | As-is, use |
| Infiltration | Air leakage during off-hours | CFM/ft², down to 0.2 |
Space Use
Lighting
| Parameter | What it is | Unit or options |
|---|---|---|
| Interior Lighting | Lighting power density | W/ft², down to 0.4 |
| Lighting Control - During Unoccupied | Share of lighting turned off when unoccupied | 0 to 0.5 (0–50%) |
| Lighting Control - During Occupied | Share of lighting turned off when occupied | 0 to 0.5 (0–50%) |
Plug loads
Energy codes don’t require plug load reductions, but buildings with high plug loads can save a lot here.
| Parameter | What it is | Unit or options |
|---|---|---|
| Plug Load | Plug load density | W/ft², 0.1 to 1.2 |
| Plug Load Control - During Unoccupied | Share of plug load turned off when unoccupied | 0 to 0.5 (0–50%) |
| Plug Load Control - During Occupied | Share of plug load turned off when occupied | 0 to 0.5 (0–50%) |
Process loads
Loads that aren’t lighting, heating, ventilation, cooling or water heating, such as data equipment.
| Parameter | What it is | Unit or options |
|---|---|---|
| Base Load | Internal heat gains from process equipment | kW, down to 0 |
Load profile charts
The Lighting Load Profile and Plug Load Profile charts show a 24-hour profile as a fraction of the peak, for weekdays (M–F), Sat and Sun. Choose Typical Operation or 24/7 Operation for buildings with floors running 24/7. The Existing line comes from the calibrated model. The Customized line follows your lighting or plug load density, the control reductions, and the HVAC startup and shutdown times on the Operations tab. The profiles themselves can’t be edited.
Operations
Operational measures don’t change the asset score, because the asset score uses typical operation schedules.
| Parameter | What it is | Unit or options | Shown when |
|---|---|---|---|
| HVAC Startup - Weekdays | When the HVAC turns on | Midnight to 8 am | Always (“24/7” if every floor runs 24/7) |
| HVAC Shutdown - Weekdays | When the HVAC turns off | Midnight to 4 pm | Always |
| Days of Operation | Last operating day of the week, from Monday | Fri, Sat, Sun, Hol | Always |
| 24/7 Conditioned Floors | Above-ground floors running 24/7 | Number of floors | Main zone |
| Floors with Lights Off | Conditioned above-ground floors with the lights off | Number of floors | Main zone |
| Unconditioned Floors | Above-ground floors that aren’t conditioned | Number of floors | Main zone |
| Unconditioned Basements | Below-ground floors that aren’t conditioned | Number of floors | Main zone |
| Occupancy during Summer Break - Lighting and Plug Loads | Whether the building is occupied over the summer | occupied, unoccupied | University buildings |
| Occupancy during Summer Break - Predominant HVAC | Whether the HVAC runs over the summer | use, off | University buildings |
| Cooling Setpoint | Occupied cooling temperature | °F, 65 to 80 | Always |
| Heating Setpoint | Occupied heating temperature | °F, 64 to 78 | Always |
| Cooling Setback | Unoccupied cooling temperature | °F, 70 to 90 | Always |
| Heating Setback | Unoccupied heating temperature | °F, 44 to 70 | Always |
| DOAS Scheduling | When the dedicated outdoor-air unit runs | occupied, 24 hrs | PTAC, PTHP, VRF, WSHP and fan coil systems |
Air-side
The air distribution systems, usually a large share of the energy cost.
| Parameter | What it is | Unit or options | Shown when |
|---|---|---|---|
| DX Cooling | Cooling efficiency | EER, up to 15 | DX cooling |
| Min Fan Operation - System Level | Minimum fan flow of the air handler | Fraction, 0.2 to 1.0 | VAV systems |
| Min Airflow Ratio - Zone Level | Minimum flow of the VAV boxes | Fraction, 0.2 to 1.0 | VAV systems |
| DX Compressor | Compressor speed control | one-spd, variable | Heat pumps, VRF, WSHP |
| Heat Pump Heating | Heating efficiency | COP, up to 4.5 | Heat pumps, VRF, WSHP |
| Furnace Heating | Furnace efficiency | Fraction, up to 0.95 | Gas or oil furnaces |
| Cooling Supply Air | Supply-air temperature in cooling | °F, 54 to 59 | Zones with cooling |
| Heating Supply Air | Supply-air temperature in heating | °F, 90 to 120 | Zones with heating |
| Indoor Fan Operation - During Occupied | Fan mode while occupied | intermittent, continuous | Always |
| Zone Fan Operation - During Unoccupied | Fan behavior at night | cycle-on-first, stay-off, cycle-on-any, zone-fans-only | Always |
| Interior Fan Speed | Supply fan speed control | one-spd, two-spd, variable (VAV: one-spd, two-spd, optimized, captured) | Always |
| Air-side Economizer - Availability | Whether an economizer is used | off, use | Systems with cooling: PSZ-AC, PSZ-HP, PVAV, VAV, SZ-CV-HW, SZ-CV-ER |
| Air-side Economizer - Integrated | Whether the economizer works together with cooling | off, use | Same as above |
| Air-side Economizer - Drybulb High Limit | Outdoor temperature above which the economizer stops | °F, 50 to 75 | Same as above |
| Supply Air Temperature Reset | Reset of the supply-air temperature | off, use | VAV systems |
| Demand Control Ventilation | Outdoor air based on occupancy | off, use | VAV systems |
| Motorized Damper | Outdoor-air damper control | use, off | Always |
| Cooling Capacity Optimization | Cooling capacity as % of existing | %, 50 to 100 | Always |
| Heating Capacity Optimization | Heating capacity as % of existing | %, 50 to 100 | Always |
| Minimum Outside Air | Outdoor air as % of total airflow | %, 10 to 40 | Always |
| Exhaust Air | Exhaust as % of total airflow | %, 0 to 15 | Always |
For VAV systems whose fan speed is captured, a chart compares the calibrated fan curve with the ASHRAE reference curve.
Water-side 1: chilled water plant
Shown when the building has a chiller plant, or a cooling tower for water-cooled DX or WSHP. The info icon shows the captured chiller capacity.
| Parameter | What it is | Unit or options | Shown when |
|---|---|---|---|
| Chiller Type | Compressor type | screw, scroll, recip, centfgl | Air- or water-cooled chillers |
| Chiller Condenser Type | Condenser cooling | air-cooled, water-cooled | Chillers without a water-side economizer |
| Water-side Economizer | Free cooling through the cooling tower | off, use | Water-cooled chillers with a water-side economizer |
| Chiller Performance | Chiller efficiency | kW/ton, down to 0.4 | Chillers |
| Chiller Size | Capacity as % of existing | %, 50 to 120 | Chillers |
| Cooling Tower Fan Control | Tower fan speed control | one-speed, two-spd, variable | Water-cooled chillers, water-cooled DX, WSHP |
| Cooling Tower Pump Head | Condenser water pump head | ft, down to 10 | Same as above |
| Chilled Water Loop Configuration | Chilled water pumping | primary-only constant, primary-only variable, primary/secondary | Chillers |
| Primary CHW Pump Head, Secondary CHW Pump Head | Pump heads of a primary/secondary loop | ft, down to 10 | Primary/secondary loops |
| Primary-only CHW Pump Head | Pump head of a primary-only loop | ft, down to 10 | Primary-only loops |
| Chilled Water Temperature | Chilled water supply temperature | °F, 41 to 45 | Chillers |
| Chilled Water Snap Control | Turn chilled water off by outdoor temperature | off, use | Chillers |
| Chilled Water Temperature Control | Chilled water temperature reset | fixed, OA reset, load reset | Chillers |
Water-side 2: hot water plant
Shown when the building has a boiler or a hot water plant. The info icon shows the captured boiler capacity.
| Parameter | What it is | Unit or options |
|---|---|---|
| Boiler Type | Boiler kind | gas, cond (condensing), steam, elec |
| Boiler Performance | Thermal efficiency | %, up to 99 |
| Boiler Size | Capacity as % of existing | %, 50 to 120 |
| Hot Water Pump | Pump head | ft, down to 10 |
| Hot Water Loop | Hot water supply temperature | °F, 125 to 185 |
| Hot Water Snap Control | Turn hot water off by outdoor temperature | off, use |
| HW (CHW) Snap | Outdoor temperature for the snap control | °F, 45 to 70 |
| Hot Water Temperature Reset | Hot water temperature reset | fixed, OA reset, load reset |
Water Heater
Shown when the building has a domestic water heater. Savings are based on the captured occupancy schedule, the water heater capacity and, for gas water heaters, the gas use.
| Parameter | What it is | Unit or options |
|---|---|---|
| Water Heater Type | Fuel or technology | gas, elec, heat pump |
| Water Heater Performance | Efficiency | % (EF or Et) or COP. Code values: gas 80, electric 96, heat pump 3.6 |
| Peak Demand | Hot water demand | GPM |
Solar PV
Generation is based on monocrystalline panels with 21% efficiency.
| Parameter | What it is | Unit or options |
|---|---|---|
| Solar PV capacity | Inverter size | kW, 0 to 999 |
| Mount Tilt | Panel tilt angle | degrees, 20 to 65. The blue button suggests a tilt based on the building’s latitude. |
Electrification
Shown when the building heats with gas or fuel oil. These options replace the heating system chosen on the other tabs, for an electrification study.
Space Heating Source is a list: As-Built/Existing, Electric Resistance, Air-source Heat Pump, Electric Boiler and Variable Refrigerant Flow (VRF). Options that don’t fit the building’s air distribution are grayed out. The heat pump is modeled at 3.0 COP, and VRF at 11 EER and 3.3 COP. The rest of the existing system is assumed to stay as it is: for example, a gas furnace in a rooftop unit can be replaced with electric resistance heat or a heat pump.