Guest Post by J C Sherrill

I am a heating and cooling contractor in North Carolina and have been following the Tiny House Blog for a few years. I have some concerns with a small indoor air space and I would like to share some information and offer some guidance to help improve your indoor air quality. The information contained could save someone’s life.

When people breathe, cook, or take showers it adds moisture to the indoor air. Small indoor air spaces can become problems from indoor pollutants and moisture. Moisture is measured as RH/relative humidity. Moisture in the air is not usually a problem in a home but when you shrink the air space and have the same volume of moisture content it can make matters much worse than you would have in a larger home where the indoor air could be better diluted by having a greater volume of air space. Going to the restroom could also become an odor problem when your entire home is only as big as some bathrooms.

Ways to improve your indoor air quality:

Ventilation is one way to improve the indoor air. Windows are passive where fans are mechanical and require power. Source containment is another. A good example would be a full floor to ceiling shower door vs. a shower curtain. No indoor plants, the dirt in the pot may also contain mold. Do not cook inside or use a microwave and an electric burner whenever possible. Use an outdoor grill for most cooking. Place a lid on your pots while cooking. Do not burn oil lamps or candles. Candles produce tremendous amounts of soot.

Another problem with tiny homes is that they are mostly built outside any building code inspection requirements and by amateurs. Tiny homes are situated for off grid or partially off grid when it comes to heating and cooking. This is usually taken care of by using LP Gas. LP gas is heavier than air. If you were to have a gas leak it can displace the air you breathe and cause death. Unvented gas appliances use the same air/oxygen; you need to breath inside the small space. Unvented LP gas appliances also add about one gallon of water to the air for every 100K Btu’s of heat produced.

Jay Shafer uses a small Newport boat heater in his tiny houses and it is vented. Good for Jay. It also brings in its own combustion air from outside so you do not need to open a window. This way the gas heater is not competing for the same air/oxygen; you need to breath inside the small space and the products of combustion are vented outside of the living space.

Most Radiant, Big Buddy and Little Buddy style heaters are not vented. Yes some of these have a low oxygen sensor but I would not trust my life inside of a confined space with one. Some of you may be saying: They wouldn’t sell them if it wasn’t safe or I have done this before and that this guy doesn’t know what he is talking about. Can we agree that Carbon Monoxide / CO is an odorless colorless gas and that it is a poison that can put you to sleep? Now just how much of a dose Carbon Monoxide and low oxygen can you stand? CO affects the young an elderly differently.

Do not place your family in danger of this deadly and silent killer.

Although I do not live full time in a tiny house I have a Big Buddy heater for winter emergencies; I would never go to bed with it on. I would crack a window about an inch or two for combustion air in an emergency situation.

LP Gas, Smoke and Carbon Monoxide alarms:

Carbon Monoxide/CO is produced when combustion occurs. If you are all electric CO is not a problem. If you burn fuel oil, gas or wood inside of your home, get a CO alarm preferably with a digital readout. Get one that will operate with a battery or 115v and battery backup. CO alarms have a recommended life of only 7 years. The new ones will chirp at their end of life cycle. If yours is old replace it. (The date should be on it or call the manufacture and ask). If you can’t find a combo unit you may need to purchase all 3 LP Gas, Smoke and Carbon Monoxide alarms to get complete coverage.

Cooking with Gas.

LP gas releases moisture when it burns. Unvented LP gas appliances add about one gallon of water to the air for every 100K Btu’s of heat produced. LP gas will compete for the same air/oxygen; you need to breath to support the flame. Coleman style camp ovens and cook grills are usually not rated for indoor use. Read and follow the instructions and keep a fire extinguisher handy.

Gas hot water heater.

Non-vented, point of use hot water heaters are great for off grid living. I bought one from E-bay for a little over $100.00 it works great. I have seen a You-Tube video where one was in use inside of the small cabin. I would recommend placing this and showering in an outside enclosure. Bring it in after use in the winter to protect it from freezing.

Moisture, mold and mildew:

Mold will not grow if the humidity stays below 60% RH. Off grid this may be a problem due to not having enough power for an A/C unit to control the humidity inside of the space. Mold grows on almost anything. Mold and dust mites need moisture to feed. Moisture is what we can control to prevent mold.

A/C units and dehumidifiers control moisture. A/C units will also cool the space while dehumidifiers will usually heat up the space. Do not leave any wood exposed to water or steam in the shower or sink backsplash area or anywhere wood will stay wet to prevent mold an mildew.

This information is provided to keep you and your family safe inside your home no matter how small. If you don’t believe me do a Google search, educate yourself, seek professional help if you need it and improve your indoor air quality.

What you do not want is to become sick or die from Carbon Monoxide poisoning or form condensation inside your living space or between the walls. Moisture + cellulose products = mold food. Look for part II How heat moves, Insulation, Radiant and Vapor Barriers

© 2011 J C Sherrill III Reproduction without permission prohibited.