Testing key to controlling mold
Q. My children have allergies to mold. I want to make my house more airtight for better energy efficient, but I heard this can exacerbate mold problems. What safe efficiency improvements can I make?
Karla S.
A. People often think airtight, musty, mold-ridden indoor air quality is the price one has to pay greater energy efficiency. Actually, making your house more energy efficient can positively effect air quality.
Mold spores are a unique indoor air quality and health issue because they can come from outdoors or indoors. With many allergens, such as pollen, the source is outdoors and an efficient airtight house keeps them outdoors. To the contrary, mold spores can live and breed inside your house. Bring in some mold spores on your shoes, flowers, etc., and they reproduce indoors on a damp surface.
First test your house for mold. Several laboratories offer home mold test kits. For a "viable" test, you grow your house test samples in a petri dish. At IMS Laboratory, it costs only about $10 for the kit. If you find mold growth, they charge about $35 more to analyze the mold types. Some types of mold cause few problems while others are quite toxic.
A better test is "nonviable" test where the sample is analyzed for many types of mold. This test costs $75. If there are dead mold spores in your test sample, the nonviable test fines them. The viable test would miss them because the dead spores would not reproduce, but live ones may still be somewhere else in your house.
Setting your heating thermostat lower saves energy and can slow mold growth. At a lower indoor temperature, less moisture content is needed in the air for comfort. This may reduce dampness. Installing more energy efficient windows in high humidity areas, such as the kitchen and bathrooms, reduces condensation. Window condensation can drip and saturate a wall or baseboard.
Installing a central air cleaner on your furnace/air-conditioner duct system removes more mold spores than a standard 99-cent fiberglass filter and improves energy efficiency. By keeping the furnace or heat pump heat exchanger surfaces cleaner, they transfer heat more efficiently.
Sealing the return air duct joints saves energy by drawing the air from rooms, not from inside musty walls, attics or basements. Sealing them also keeps mold spores from being drawn into the duct system. Black Gorilla tape or spread-on sealing compounds work well to seal leaky joints.
It is difficult to completely rid a house of mold spores once they are established. They can remain dormant for a long time. One EPA-registered mold-control liquid by Concrobium (www.concrobium.com) encapsulates existing mold spores on surfaces so they cannot reproduce and inhibits growth from new spores brought indoors. To treat large areas, Home Depot rents foggers for applying this product.
The following companies offer home mold test kits: Home Health Science, (877) 276-8250, www.moldcheck.com; IMS Laboratory, (877) 665-3373, www.homemoldtestkit.com; Prolab, (800) 427-0550, www.prolabinc.com; and Tennessee Mold Consultants, (865) 558-9772, www.tennesseemold.com.
Q. I am planning to build a solar room heater similar to the one you described. I can use glass, acrylic or polycarbonate for the clear top pane. Does the thickness of the top pane effect the efficiency?
Ron H.
A. Whether the clear top is 0.80-inch or 0.12-inch thickness does not have a significant impact upon its efficiency or its insulation value. For more top insulation, use two thin panes with a small air gap between them.
The only reason to use more expensive thicker material for the clear top pane is for strength. Polycarbonate (bulletproof glass) is virtually unbreakable, but it is very expensive and yellows a bit from the sun.