Closing vents in unused rooms increases duct pressure and wastes energy

Residential HVAC systems are designed for a specific static pressure. Closing vents raises duct pressure, which forces air through leaks, increases fan energy consumption, and can cause the evaporator coil to freeze. Per ASHRAE research, homes with closed vents use 5-10% MORE energy than homes with all vents open. The correct approach for zoning is a variable-speed system with zone dampers.