Lighting's affect on compressor load

[TeamESI]

Hello everyone,

I'm new to the site. Lots of great stuff here.

I'm trying to understand what how lighting affects the load on a compressor. For example, if a cold storage facility is lit using 400 watt metal halide fixtures, and the fixtures are replaced one for one with an LED fixture using 170 watts, how much of the compressor load would be reduced and how would that translate to $'s.

There was a grocery store near me who recently retrofitted the lighting in their frozen reach in display cases from fluorescent to LED. The owner showed me the calculation for compressor load reduction that he was shown. I wanted to run this past everyone to get feed back.

There were 3 constances to the formula:

1. $KWh rate = $0.09
2. Electrical Wattage to Compressor BTU/hr conversion = 3.412
3. EER compressor efficiency BTU/hr = 7.49

For the entire store, the retrofit reduced 43,756 of lighting KWh. The formula for compressor KWh savings is as follows:

Lighting KWh removed x Electrical Wattage to Compressor BTU/hr conversion / EER compressor efficiency BTU/hr x $KWh rate = $'s saved

or

43,756 x 3.412 / 7.49 x $0.09 = $1,793.94

Questions I have:

1. Agree or disagree with the formula?
2. If the formula is correct, would the same formula apply in a large cold storage facility when removing a fixture that uses 465 watts and replacing it with one using 170?
3. Are there any potential drawback when reducing that much lighting load in a large facility?

Hope this wasn't too long. Thanks for your consideration.