Building Energy Savings 101:

A musty smelling basement is often a sign of excess humidity in your home. The first thing a homeowner should do is establish the level of humidity in the home. Installing an instrument called a hygrometer does this. This measuring device, sometimes called a humidiguide or a humidity indicator measures the level of moisture or water vapour in the air. There are two types of hygrometers, mechanical and electronic. You will usually find these at your local hardware or building supply in the area where the thermometers are sold. Sometimes they are combined in one instrument. The mechanical type is the most inexpensive, they are reasonably accurate and once calibrated, do not require batteries and can be physically adjusted if found to be out of calibration. Their draw back is they loose their accuracy if the humidity does not change over a long period of time. The electronic models are very accurate in the mid to high ranges. Slow response to changes in humidity and lack of accuracy at low humidity coupled with the need for batteries are the major shortcomings of this type.

These instruments measure in percentages. The commonly accepted levels of humidity are a minimum of 30% humidity in the winter and 60% as a maximum reading during the summer months.  During the winter if you notice your skin is very dry and you get excessive static from doorknobs or your carpets, it is likely the home lacks humidity. On the other side is the musty smell, excess condensation on your windows and mould are also side effects when the levels are above 60%. Each home is different and while these numbers are the accepted averages, some homes at 50% humidity may be too high. There is an increasing concern over mould in today’s homes and maintaining your humidity is the number one method of controlling conditions that permit mould growth.

Once you have bought a hygrometer, do not expect instant results. It can take over two hours for this instrument to provide a stable reading. Do not position it anywhere that heat can come in direct contact with the instrument. Make sure you follow the manufacturer’s directions for calibration and then do this annually to reset your instrument. Position this instrument where the problem appears to be or in the area of the home that you spend most of your time.

The vast majority of moisture issues are in the basement.  This is where different forms of dehumidification come into the picture. There are chemical absorbent bags and some people even use road salt. The salt is contained in a bag; it absorbs the water and drips into a pan for disposal. Both of these methods are very basic and not extremely efficient. The two most common types of dehumidifiers are the dehumidifying ventilator and the heat pump style. The ventilator type operates on a sensor and an exhaust fan. This type of dehumidifier works best in a basement. Ventilators use less electricity than the heat pump style but are not effective in very hot and muggy weather as they reintroduce exterior air to the home. If this unit is not air balanced it can cause combustion gas spillage if you use wood or gas for heating or hot water. A professional HVAC technician who understands these units should install it.

By far the most common type of dehumidifier used today is the heat pump style. They use a fan to draw the indoor air over a coil that is refrigerated to near freezing. The excess moisture in the air turns to water when it hits the coil. Most of these units have a small container to hold the water. The better models can be hooked to a garden hose and drained to a sump hole or the floor drain in your basement. The heated dry air then returns to the room. This is accomplished by using the heat from the compressor and fan motor.  These units are not cheap, a good one with the energy star rating can easily run over $300.00 and will cost anywhere from $150.00 to $180.00 per season to run. This is based upon operating for approximately 80 days a year. Take your time buying a dehumidifier and check the efficiency factor on the unit, the higher the EF rating the better. There are different sizes, know the square footage of your home before you buy one. Some have different speeds and check to see whether it has an automatic defrost. All of these features are important. Try and get the unit in a central location, not in a basement bedroom. They are noisy during operation.  A laundry room works well but stay away from the furnace. Follow the manufacturer’s instructions for cleaning and maintenance.

One last tip, look outside your home. Are your eavestrough downspouts draining a good distance from the home? Is your landscape work containing water against the foundation? It should drain away at minimum of ¼” per foot. Proper management of ground water can go a long way to helping a damp basement.