Lighting and Facilities Calculators
Lumen method lighting, LED retrofit payback, heater power, fan and pump affinity laws, data centre PUE and rack cooling calculators.
These calculators cover building and plant loads: how many luminaires reach a target illuminance, what an LED retrofit saves and how long it takes to pay back, what heater rating raises a volume of liquid by a set temperature, how much energy slowing a fan or pump saves, and how a data centre overhead and cooling load compare with its IT load.
Where to start
- Lighting Level (Lumen Method): Number of luminaires for a target illuminance.
- LED Retrofit Savings and Payback: Energy, cost saving and payback from replacing old fittings with LED.
- Fan and Pump Affinity Laws: Flow, head and power at a new speed, with the energy saved.
- Data Centre PUE: Power usage effectiveness from total facility power and IT load.
All 13 calculators in this category
Lighting
- Lighting Level (Lumen Method): Number of luminaires needed for a target illuminance. Open in Elecmetric
- LED Retrofit Savings and Payback: Energy, cost saving and payback from replacing old fittings with LED. Open in Elecmetric
- Lumens, Lux and Area (any two): Enter any two of luminous flux, illuminance and area. The third is calculated, with an optional factor for lumens that do not reach the surface.
- Candela, Lux and Distance (any two): Enter any two of luminous intensity, illuminance and distance. The third is calculated with the inverse-square law and the angle of incidence.
- Candela and Lumens from Beam Angle: Convert between luminous intensity (candela) and luminous flux (lumens) for a beam of a given full angle. Enter one of the two.
- Lumens and Watts (luminous efficacy): Enter any two of luminous flux, electrical power and luminous efficacy. The third is calculated.
- Lighting Power for a Target Lux: Lamp lumens and electrical watts needed to reach a target illuminance on an area, with utilisation and maintenance factors.
- Millicandela and Lumens from Beam Angle: Convert between luminous intensity in millicandela (mcd, as on LED data sheets) and luminous flux in lumens for a beam of a given full angle. Enter one of the two.
- Illuminance from Lamp Power (watts to lux): Estimate the average lux on an area from the electrical watts of the lamps, their luminous efficacy, the area and the utilisation and maintenance factors.
Industrial Electrical
- Heater Power for Heating a Liquid: Electrical heater rating to raise a volume of water or similar liquid by a set temperature in a set time. Open in Elecmetric
- Fan and Pump Affinity Laws: Flow, head and power at a new speed, showing the energy saved by slowing a fan or pump. Open in Elecmetric
Data Center Electrical
- Data Centre PUE: Power usage effectiveness from total facility power and IT load. Open in Elecmetric
- Rack Heat Load and Airflow: Convert IT power to heat load, cooling tons and the airflow needed for a given air temperature rise. Open in Elecmetric
What these calculators do not cover
The lumen method gives an average illuminance estimate, not a point-by-point layout, and does not replace a lighting design to the applicable standard. Savings and payback depend on the tariff, hours and prices you enter. The cooling results are heat load conversions, not a cooling system design.
Cross-check: all 13 calculators listed here are compared with 195 reference calculations written separately from the engine. This confirms the arithmetic and selection rules. It does not confirm that a standard table or convention matches your standard or manufacturer data.
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