When it comes to intake air for your compressor, cooler outdoor air is better than hot indoor air. Denser air requires less energy to compress. Though most compressors are located inside a plant building, many times the suction could easily be ducted to draw air from outside the building. Outside air will generally be cooler and, in some cases, much cooler than ambient air near the compressor. According to some estimates, lowering the intake air temperature from 90F to 70F will lower operating costs by almost 3.8%.