Q+A with Rob Troxler of Phi Builders and Architects on the eco-benefits of HRV and ERV systems

HRV (heat recovery ventilation) and ERV (energy recovery ventilation) systems are becoming a standard component of today’s well-insulated, energy-efficient “tight” homes. They filter air to mitigate toxins and purify the home while saving heat energy. Rob Troxler of Phi Builders and Architects explains why he selected an HRV system for a home on the Saint George peninsula featured in Back to Natural , page 92.

Q. Why was an HRV needed?
A. The owners wanted a very tight, efficient home with good air sealing and a high R-value. This necessitated a way to turn over the air to keep the interior healthy and balanced. We determined that an HRV (rather than an ERV) would be necessary based on the energy efficiency of the unit, projected humidity levels within the dwelling, seasonal considerations (windows open in summer versus air-conditioning, for example), and the insulation level (high R-value) of the building. HRVs tend to be best for removing humidity in winter more than summer, while ERVs moderate humidity better in summer than winter.

Q. What model was selected?
A. We chose the Lifebreath 155 Max HRV for its efficiency: it recovers 85 percent of heat energy. It’s the best option for a cold winter with minimal humidity, such as on an island in Maine. The head unit is located in the attached garage, and ducting runs to various areas of the house for optimized airflow, with a remote keypad control unit located in the entry of the home.

Q. Have there been any drawbacks?
A. There’s certainly an electrical cost to run the HRV that is not necessarily offset by the increased efficiency of the home. This said, the long-term health (both home health and the health of the home’s occupants) should be increased with this system in place—something that should create a potential cost savings over the years. To the cynical, an HRV may be just another mechanical thing that will eventually fail, but if a sincere attempt is made to consider and weigh all of the various factors before installing an HRV, the benefits should far offset any potential downside.