Construction standards ensure that homes today are airtight. While great from an efficiency standpoint, the lack of exchange between inside and outside air poses several problems. The largest concern is air quality.
Like the outdoors, there are various pollutants in our homes. These come from numerous sources, including the things we cook and clean with. If no air can escape, then this means these pollutants can accumulate and become quite potent.
While opening a window or door can let some pollutants out, doing so allows any generated heat or coolness to escape too. This is where air exchangers come in: they mediate the exchange of indoor and outdoor air, conserving some of the heating and cooling in the process.
How Air Exchangers Work
Air exchangers, known also as mechanical ventilation systems, remove moisture and toxins from the home and provide fresh, pre-heated/cooled air. They draw in and exhaust air simultaneously using fans and air ducts. During the exchange, these machines transfer heat from the outgoing stream to the incoming one. They do so without mixing them, as this would contaminate the new air.
Mechanical ventilation systems come in two forms: Heat Recovery Ventilators (HRV) and Energy Recovery Ventilators (ERV). Both can recover anywhere between 50% and 95% of the heat in air expelled from the home. The chief difference is that ERVs can recoup moisture between the two airstreams, called latent heat. This makes it useful when dehumidification is required.
ERVs require different components to conserve latent heat and are often more expensive. Depending on the climate, HRVs are typically sufficient. Places that experience dry, warm seasons are more in need of ERVs than those homes in temperate climates.
