Lighting Control Calculator

Lighting power density check per ASHRAE 90.1 with dimming zone, sensor, and control device counts.

Floor area (sq ft)

Building type (1-10)

Installed lighting (W)

Lighting zones

Daylight zones

Tab to move between fields

Code LPD limit (W/sq ft)

0.82

Actual LPD (W/sq ft)0.82

Max allowed watts8,200

Occupancy sensors8

Daylight sensors3

Control relays8

Contactor panels1

Est. annual savings (kWh)9,379

Est. annual savings ($)$1,125.00

Code CompliantYes

Lpd Margin (%)0%

Time Clocks1

How to Use This Calculator

Enter the total floor area in square feet and select the building type (1–10) to look up the ASHRAE 90.1 LPD limit.
Enter installed lighting wattage if known, or leave at 0 to use the code maximum for budgeting.
Enter the number of separately controlled lighting zones and the number of daylight zones with windows or skylights.
Read the ASHRAE 90.1 LPD limit (W/sq ft), maximum allowed watts, and whether your design is code compliant.
Use the occupancy sensor, daylight sensor, and control relay counts to size your lighting control system.
Review the estimated annual energy savings in kWh and dollars from controls.

What each input means

Floor area (sq ft): Total floor area of the space or building.
Building type (1-10): 1=Office, 2=Retail, 3=School, 4=Hospital, 5=Hotel, 6=Warehouse, 7=Restaurant, 8=Manufacturing, 9=Parking, 10=Religious.
Installed lighting (W): Total installed lighting wattage. Leave 0 to use the code maximum.
Lighting zones: Number of separately controlled lighting zones.
Daylight zones: Zones with access to daylight (windows/skylights) requiring photo sensors.

Code LPD limit (W/sq ft): Maximum lighting power density per ASHRAE 90.1 Table 9.5.1.
Actual LPD (W/sq ft): Installed or calculated lighting power density.
Max allowed watts: Total wattage allowed by code for this building type and area.
Occupancy sensors: Occupancy/vacancy sensors needed (one per zone).
Daylight sensors: Photosensors for daylight-responsive dimming.
Control relays: Switching/dimming relays (one per zone).
Contactor panels: Lighting relay panels (24 relays each).
Est. annual savings (kWh): Estimated annual energy savings from controls.
Est. annual savings ($): Estimated annual cost savings at $0.12/kWh.

Identify Input Parameters
4 parameters
Floor area (sq ft) = 10000, Building type (1-10) = 1, Installed lighting (W) = 0, Lighting zones = 8 = 5 input(s) provided
Calculate Code LPD limit
Code LPD limit = lpdEntry.lpd
0.82 = 0.82
Calculate Actual LPD
Actual LPD = actualWatts / floorAreaSqFt
0.82 = 0.82
Calculate Max allowed watts
Max allowed watts = lpdLimit * floorAreaSqFt
8200 = 8200