Under-Floor Heating and Cooling. With rising energy costs, consumers demand solutions for lowering their heating and cooling costs. Access floor plenum systems (under-floor air) can provide energy savings up to 20%–30% over traditional overhead ceiling air systems, due to: An increased number of ventilation systems Higher supply air temperatures Reduced AHU (air handler unit) capacitance Reduced fan power Access floor plenum systems also offer personalized comfort control by room or even by floor area, providing optimum temperatures for individual work areas. Cleaner air is another benefit of under-floor heating and cooling systems. Conventional overhead HVAC is designed to force cool, clean air down from the ceiling. Because hot air rises, this cool air must mix with the warmest, most polluted air before reaching the occupants.