It’s a scientific fact that less energy is required to heat or cool a dry environment as opposed to a damp one. In one Dept. of Energy test, the heating and air conditioning costs of homes with crawl spaces and mechanical ventilation similar to our units saw a 17% reduction for the whole house. Each house will vary but the units will increase efficiencies of the HVAC systems. In winter the exhaust rate is minimal to keep air circulating, with hardly any impact on reconditioning air. In the summer which lasts only for a few months, the unit is on high only if needed to remedy problems. When conditions are controlled the unit runs in maintenance mode at a low rate of 40 cfm. It’s a controlled sensible ventilation that at high rate, is equivalent to running 2 bathroom fans. Once optimal conditions are achieved the unit goes into low speed to maintain the environment. HVAC systems use energy to heat and cool. Ventilation requirements are essential for improved health and maintaining the structural integrity.