Balanced Ventilation is a Winning Proposition
Most clients have only minimal knowledge about these systems. Do you know how to explain their benefits?
Although balanced ventilation systems with dual fans are top-of-the-line when it comes to making homes healthier and more comfortable, homeowners need help understanding them.
The most comfortable and energy-efficient balanced ventilation option is the heat, or energy recovery, ventilator. In an HRV the fans push supply and exhaust air simultaneously through a heat exchanger core, where heat from the warm air stream (stale exhaust air in winter and fresh incoming air in summer) is transferred to the cooler stream. An ERV does the same while also transferring moisture from the more humid to the less humid air stream, reducing interior condensation in winter and lowering the latent load on the air conditioner in summer.
The Pros
This technology's most compelling benefits relate to air quality and energy savings.
Air quality is a natural homeowner worry in airtight new or newly remodeled homes. What many homeowners don't realize, however, is that an HRV or ERV makes that airtight building shell a perfect opportunity to ensure healthy indoor air.
For fresh air, older homes relied on infiltration through gaps in the building shell. But even the draftiest of those homes may not get enough infiltration on a calm winter day to meet the minimum ventilation standards set by ASHRAE 62.2, so it's easy for moisture, pollutants and odors to build up inside. Balanced ventilation eliminates the problem by not leaving the fresh air supply to chance. The tighter the shell, the more predictable the air supply. As a Building Science Corporation publication puts it: "Once you eliminate big holes it becomes easy to control air exchange between the inside and the outside."
Homeowners will also be glad to learn that most HRVs include filters that remove dust and other contaminants from the incoming air stream.
When it comes to energy, the Department of Energy estimates that these units transfer 70% to 80% of the heat in the warm air stream to the colder one. During winter, that's less heat lost to the outdoors, and less cold air delivered to the home's rooms.
One benefit that is not emphasized enough is this technology's versatility. The HRV can be installed as a standalone unit with dedicated ductwork, or integrated with the home's air handler. Exhaust ducts can even be run to the home's baths. What homeowner wouldn't be happy to eliminate those noisy bath fans?
Not for all homes
HRVs do have a higher installed cost when compared to an exhaust-only system, which makes them most attractive to homeowners who pay a lot of money for space conditioning: people who live in very hot or cold climates with high electric rates. But those regions still represent a large potential market.
Of course, the choice between an HRV and an ERV depends on factors that include the size of the home, its airtightness and the prevailing climate. And these units have to be correctly balanced to deliver their promised benefits. That puts the HVAC pro with knowledge about this technology in a strong position to help homeowners save money and breathe easier.