Does anybody know the formula for calculating energy savings from switching Magnetic ballasts and lamps, over to electronic ballasts and lamps for 2x4 lay in troffers.

For arguments sake, lets say 4 lamp fixture w/ 34 or 40w lamps magnetic

And 4 lamps 32 watts electronic

raob x volts x nof - ranb x volts x nof

where:

raob - rated amps of old ballast
volts - duh
nof - number of fixtures
ranb - rated amps of new ballast

How about the reduction in heat generated?

If it is a massive building then yes you could figure it in. I might have info on that. I will see If I can locate it. Living in AK, you do not really think of that since we only use AC in our IT rooms. Most buildings I deal with are for the most part are well insulated Any heat loss form the lights that is picked up by the heating systems would me insignicant.

Let me put it this way .... when I converted an office building from T-12's with conventional ballasts, to T'8's with electronic ballasts .... the math gave me a very conservative number! IIRC, I was expecting savings of about $250/ month .... while the actual saving was nearly $400/mo.

Actual amp readings, before and after, showed about a 35% reduction in current drawn. This is not considering the lesser load on the air conditioning, due to the lower operating temperature.

I was changing things 'bulb for bulb.' If you are replacing 4 lamp fixtures with 3 lamp fixtures, expect further savings.

I was thinking more of this formula

# of luminares x total W per luminare x Annual operating hrs x Energy cost per KWH= First year energy cost/1000

Knowing amperage is not accurate enough. There is input amps and out put amps. Example, a 400w MH fixture has a total input of about 465W Amperage on ballast is not accurate in my experience. Need to measure True Power (watts)

See if this will help.

http://www.goodenergy.com/electricity_consulting_products/lighting_retrofit_saving_calculator.aspx