When you walk through a bright and airy underground home, it might not dawn on you at that time, but there are ventilation systems at work there, to keep the air fresh. Subsurface habitats need air exchange systems due to the buildup of CO2, mold spores, tobacco smoke and sometimes even radon in underground areas.

Earth-sheltered and underground homes are certainly nothing new to MOTHER EARTH NEWS' readership. After all, this magazine has been touting the advantages of such dwellings (low fuel costs. While fully subterranean homes can feel like grim bunkers, homes built partially into hills, cliffs and bluffs peek out from underground through glassy ‘eyes’ to gain daylight access and views of their surroundings.

Most earth-sheltered homes have state of the art systems for incoming air, so that it can be properly filtered.

As much as people who live 'down to earth' lifestyles like to keep things simple, a ventilation system really should be at least partially automatic.

Exchange This, Please ..
Underground homes benefit greatly from ventilators that recover energy. They are called air to air heat exchangers, and they remove the polluted or stale air from your home, replacing it with fresh air from outdoors.
In order to conserve the most energy, these ventilators pass the warm air moving outdoors through a component inside, a heat exchanger. There, heat that is headed outdoors is actually transferred into the incoming air, which is cool. This process will keep you warmer in the winter, and save a lot of energy, since your heater won't be needed for warming incoming cold air.

Humid Beings ..
During the summer months, the outgoing air works to cool the warm, incoming air, which maintains comfort in warmer weather. Ventilators that work on the energy-recovery system can be run with humidistats or timers. Although they tend to remove any excess humidity, you can even set them up to add more humidity to the air in your home, as needed.

Underground House and Ventilation

When you're looking into purchasing an energy-recovery ventilator, keep in mind that they may sound more technically difficult than their workings actually are. The ventilator you want is different from a heat recovery ventilator. In the unit you want, the heat exchanger will transfer some water vapor into your incoming air. Heat recovery ventilators only transfer heat.
You can keep the humidity of your earth-sheltered house more constant when your unit transfers some moisture to the air coming in, which is generally less humid. This helps your home to maintain a more constant level of humidity. The core of the heat exchanger will also stay warm, which minimizes freezing problems in colder climates.

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Breathe Light Into the Room ..
Some earth-covered homes also feature skylights that can be opened, which is a much simpler way of allowing air flow from the front of the house to the back. But that system only works when someone remembers to open those skylights. You may also see conduits or tubes in the front of the house (below the level where they would affect the natural look) that run from the front to the back of the house.

Many people who dwell in earth homes also have plants, to bring nature in. Plants generate oxygen from the carbon dioxide we breathe out, though not on a large enough scale to ventilate an entire house (the Biosphere in Arizona discovered this quickly). Some homeowners may use a combination of systems, including a 'passive stack' system.

Earth Berm House with Vent on Top

For smaller homes, tubes or conduits can move air enough to vent the structure, and with the temperature differences, it works fairly consistently. Homeowners will sometimes rig a mechanical assist to this system, to be sure of proper ventilation at all times.

Conclusion ..

When planning and designing your underground house be sure your contractor covers the ventilation system in detail upfront. You'll breathe a lot easier if you do. :)

Written by Kevin Knatloa

First Published on November 05, 2012

Updated November 22, 2013

External Links

Heat Exchangers and Energy Recovery Ventilators
http://www.ag.ndsu.edu/pubs/ageng/structu/ae1393.pdf

Also called 'earth shelter' or 'solar' homes, subterranean homes have been talked about since the seventies for their ability to conserve energy. The production cost of these homes' architecture and well-engineered plans have been very highly priced, historically.

You can purchase a kit that has all the materials along with the directions included in it. On the other hand, you can buy the materials yourself, especially if you have some experience with these endeavors and know what you are doing. People who are doing this for the first time will most likely need the advice of an expert underground home contractor and builder.

Subterranean homes give you a steady all-year round temperature. These types of 'underground' homes feature excellent cooling and heating efficiencies and ample yard space. Unique architecture is another feature of these types of homes. Nearly disaster proof, subterranean homes offer comfort and safety that you can find in an easy-to-install kit for your convenience.

The Truth of the Matter

Subterranean homes sometimes give the misconception of being as dimly lit and damp as caves. People have the notion that underground-dwelling places are automatically dirty, dark and unsafe. This cannot be further from the truth. Although it is true that the underground dome homes are modeled according to the architecture of igloos, the interior of these homes are as attractive and as modern as regular homes.

Subsurface House

As a matter of fact, the fact that light travels much more effectively through homes that are subterranean ensures a well-light, bright and sunny home. You can even have your own subterranean home kit customized to fit your needs and design preferences.

Subterranean home kits begin approximately six feet underground, where the temperature is a consistent fifty degrees all year round. Too chilly for comfort, you can manipulate the parts of the home that is exposed to sunshine, saving you eighty percent of energy compared to a regular home's system for heating. Kits of subterranean homes do not need cooling in the summer, saving you the need to acquire an air-conditioner.

What is the Secret?

The key to the success of many subterranean designs are the dome-like structures. The dome that is built with the house lets it withstand all the pressures that the earth produces around it. Prize fighters. Rectangular homes have a harder time withstanding this kind of weight unless they have numerous support beams.

Subterranean home kits normally come with materials, directions and plans. There are other kits that let you purchase all the separate materials yourself and build the house according to specific instructions. If you can afford to live 'on site' as you build your home, you will be able to enjoy building your home at a fraction of the cost of normal subterranean home construction built by a contractor and crew.