Modern homes typically are tightly constructed, with a prime focus on energy efficiency. This is a good thing for saving energy, and it saves your household on electric and gas bills. There is a potential downside to an airtight house, though. Unless the home has an effective ventilation system, there’s no way to exchange stale inside air with fresh outside air, other than opening windows. This is where a balanced ventilation system — for example, a heat recovery ventilator — can play an important role in preserving indoor air quality. The bonus with an HRV (or its close relative, an energy recovery ventilator), is that it also helps with home heating and cooling.
In any ventilation system that draws fresh outside air into the home, a problem arises when the outside air adds to the heating or cooling load inside. A heat recovery ventilator (or HRV) addresses this issue by maintaining separate but parallel airstreams, incoming and outgoing. As the air moves in both directions, heat energy from one airstream is transferred into the other. In the winter, heat from outflowing air transfers over to the incoming cold air, making the injection of outside air less of a challenge for your heating system. In the summer, heat from inflowing outside air is transferred over to the air that’s leaving the house.
An HRV has an additional capability: It not only transfers heat energy but also transfers moisture. As a result, during cold winter weather, when the air gets especially dry, some of the marginally more humid indoor air that’s being exhausted will transfer over to the dry inflowing air to help maintain a comfortable humidity level inside. To a limited extent, an ERV may serve the opposite purpose during hot, muggy summer weather, helping your A/C dehumidify the indoor air.
HRVs and ERVs don’t work in every climate (they’re less effective in areas with mild winters and summers), and they can be relatively expensive to install.
For more information on the benefits HRV/ERVs can provide your Portland area home, please contact us at Roth Heating & Cooling.