Impacts of ventilation strategies on energy consumption and indoor air quality in single-family residences

Abstract

This report compares the impacts of five different ventilation strategies on the overall energy consumption of superinsulated houses in the Northwestern United States. The strategies examined are: (1) natural ventilation, (2) balanced ventilation with an air-to-air heat exchanger, (3) exhaust ventilation without heat recovery, (4) exhaust ventilation connected to a heat pump to provide space heating, and (5) exhaust ventilation connected to a heat pump to heat domestic water. A modified Transient System Simulation (TRNSYS) residential load model incorporating the Lawrence Berkeley Laboratory (LBL) infiltration model, and a modified TRNSYS domestic hot water model, are used to simulate the energy consumption associated with each strategy. The domestic hot water model is used to determine the amount of useful heat supplied by an exhaust ventilation heat pump as a function of hot water demand schedule and storage tank size. The simulations are made for cities with: (1) a moderate coastal climate, (2) a windy cold climate, and (3) a calm cold climate. They show that total energy consumption (space heat + domestic hot water) can be reduced by 9 to 21% by using mechanical ventilation systems with heat recovery. These savings, compared with energy savings of 18 to 21% achieved by superinsulating the same houses, indicate that the choice of ventilation strategy can have a significant effect on energy consumption. The comparisons also show that for the same effective ventilation rate, houses with mechanical ventilation systems (especially those with exhaust fans) have uniform ventilation and therefore better indoor air quality.