Underground Home Ventilation

When you build an underground home, there are few things more important than adequate ventilation. Otherwise, you may be exposed to excess CO2 and suffer a lack of oxygen. The use of an energy-recovery ventilator, also known as an ERV, or a heat-recovery ventilator, also known as an HRV, is of vital importance in underground homes.

Converted Underground Missile Silo Home

Most builders of earth homes will choose a central fan-integrated system, an exhaust-only system or a balanced ventilation system that uses an ERV or a HRV for proper ventilation.

A balanced ventilation system is not cheaply installed, but they do offer you a reasonable cost of operation, compared to any other ventilation systems.

An ERV or HRV delivers fresh air to the interior of your home. Neither one was designed to make up for kitchen or bath exhaust fans or combustion appliances. They are not designed to heat your home. They both use electrical energy in order to operate their fans. In addition, they may lose cooling or heating energy since they are moving heated or cooled air from your home.

HRV fans will pull fresh air into your home while they exhaust the stale air. Usually, the fresh air is brought into the bedrooms and living room, and stale air is pulled from the laundry and bathrooms. Both types of air will stream through your HRV. In addition, the appliance core will allow some of the heat from the stream of warmer air to transfer to the air stream that is cooler. By this method, the system can recover some heat before it is expelled from your house.

ERV or HRV - Huh?

An ERV will accomplish the same things as an HRV. Additionally, the ERV will allow some moisture in the humid air stream to transfer to the dryer air stream. Transferring this moisture does not mean that much of the two air streams is mixed.

Underground homes have more need of ventilation than conventional homes. ERV's or HRV's can provide fresh air for your health, remove any odors from your home, lower indoor humidity and dilute pollutants from your indoor air. Using proper ventilation, you can keep your home's air fresh and healthy for you and your family.

When you are ventilating your home, the system should account for the fact that lower humidity is better than high humidity. But proper ventilation can only reduce the indoor humidity if the air outside is dryer than the air indoors. Colder air isn't as humid as warmer air, so the only time a ventilation system will help in lowering your indoor humidity is when the weather outside is cold. When you ventilate your home in hot weather, it may even raise the humidity level.

Choosing between ERV's and HRV's does not depend only on climate. You can use ERV's in cold climates, contrary to HRV sellers' claims, and in humid climates, an ERV won't act like a dehumidifier, as their sellers sometimes claim.

When your HRV or ERV works to ventilate your air-conditioned house, the air coming in is cooled by the air going out. This only works if your house is air conditioned, though. If your inside air is warm, too, there isn't much heat exchange.

I'm Venting!

Whether you use an ERV or HRV, you'll be satisfying your underground home's need for proper ventilation in every season, even though they do have their minor downfalls.