The condenser is the greatest energy user in any standard air conditioning system. The condensers job is to eject heat from the building to the atmosphere. How much heat is rejected per kW gives us the EER rating, or Energy Efficiency Ratio.
In normal air conditioning systems, condensing temperature is always higher than the outside air temperature by more than 20 degrees. Utility studies have determined that summertime condensing temperatures for roof mounted air conditioners can be 140 to 150 degrees. A 10 degree rise in condensing temperature will cost 2 EER points. Likewise, a 10 degree drop in condensing temperature will result in a gain of 2 EER points. At summer condensing temperatures, de-rating roof top units to 6 to 7 EER is common. Typical modern equipment currently on roof tops is rated 9 to 11 EER. When condensing temperatures get to |
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140 degrees, this rating drops to 6 to 7 EER. This results in power consumption of 2 kw/ton/hour. With over 3,000 cooling hours per year in many climates the resulting loss of efficiency and cost of cooling is oppressive, and will continue to worsen with rate increases.
Why is purchasing new “energy efficient” rooftop equipment not the best solution? Because the efficiency of new energy efficient equipment still degrades quickly as the outdoor air temperature increases. A US Energy Solutions condenser retrofit in most climates can achieve the following benefits:
- Cool condensing temperature to the 90 degree range
- Reduce kilowatt consumption 35%
- Lower costs to $ .52 cents/ton/hr
To further enhance operating performance and lower operating cost, we can make changes to the compressor for which the net savings will be in the 50% to 60% range over the existing air cooled configuration.
US Energy Solutions can improve the net operating efficiency to a 14 EER and use less than one kw/per ton/hr (.85 kw=14 EER) and that rating will not degrade like new “efficient” equipment will.
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