HIBERNATING IN A HEALTHY HOME Once again, Canadians prepare for the long, dark months spent indoors. Like burrowing animals, we fuss about our homes waiting for the long cold months ahead. We store our lawn furniture, rake our leaves and put the lawn mower away for winter. Snow tires are installed and shovels are taken out of storage. OK, we’re ready for Old Man Winter, we haven’t forgotten anything……or have we? Canadians spend just about all of our time indoors during winter months. Have we prepared our homes for the change of seasons? Colder temperatures make our homes work harder at keeping us comfortable. Have we done everything we can to ensure a safe, energy efficient, healthy heating season? Here are some healthy hibernating tips for your home and family. Cooler climate generally arrives after the leaves have fallen. Tall deciduous trees that grow close to the home tend to shed their leaves on our roofs and ultimately block our eavestrough and down spouts. Ensure your eaves and down spouts are free of debris. Inspect your fireplace damper for operation. Does your damper (located about 12” up your chimney, a door-like mechanism that controls smoke out and cold air in) operate efficiently? Does it open and close completely? Is your chimney clean and in good repair? Have a WETT (Wood Energy Technology Transfer – A non-profit training and educational association – www.wetinc.ca) certified inspector/cleaner service your chimney, wood fireplace, and wood stove annually. Are your smoke detectors and carbon monoxide detectors working? Have you installed new batteries? The building code now requires an operating smoke detector on each floor of your home. Have you removed your garden hose and shut off the exterior tap from indoors? Most homes are equipped with an indoor tap that remains closed during winter while the outdoor tap is left open and drains empty. Frozen exterior hose spigots are common and expensive to repair. Inspect all your exhaust and air inlet through wall fittings. Are bathroom and dryer vents clean and operating? Have grass clippings or pollen plugged your make-up air or heat recovery ventilators’ inlet grills? Clean all vents to ensure smooth operation and required air flow to combustion devices (boilers, furnaces and hot water tanks). Ensure all direct vent gas fireplace wall fittings are free of leaves and debris. Cold winter days restrict the amount of natural ventilation we are exposed to (through windows). Healthy Hibernators now must rely on exhaust fans and air exchangers to dilute moisture and household generated biological and chemical air quality loads. Household ventilation and dilution can be simplified by imagining your home is a giant glass fish tank. The walls of this fish tank are made of magnifying glass and therefore all dust particles (Respirable Suspended Particles – RSP’s) are visible. Over time the occupants of this fish tank generate dust, (skin cells, dust mites, dust mite fecal matter, dander, hair, lint, bacteria, viruses and moisture). Occupant activity may introduce chemicals, soot, tobacco smoke and odour. With our magnifying glass walls we can see the accumulation of these conditions. The small size of these nano particles (0.3 to 10 microns) means they are aerosolized or airborne all day. A micron is 1/1,000,000 of a meter small. The average human hair is 60 microns in diameter. Typical household activity and forced air heating systems keep these small particles airborne where they are easy to inhale and difficult to clean. After a couple of months of this type of dust accumulation, it is easy to imagine the interior of our fish tank as a veritable sand storm. If a sand storm is raging inside our homes and clean air is available outside our homes, we must ventilate. Ventilation and dilution simply implies mechanically introducing dry, clean, fresh air from outside by utilizing a whole house ventilator (HRV), or an exhaust only device (e.g. bath fan). If we were to mechanically pump all the contaminated air out of our fish tank we would produce less air in the tank compared to outside (building depressurization). This negative pressure would draw clean fresh outdoor air into our tank through leaks and cracks in the tank (wall and roof) assembly. The small size of these leaks and the large number of leaks and cracks found in the fish tank means we don’t feel cold air on our bodies coming from any specific location. Fresh air is introduced into our environment by simply exhausting contaminated air from our space. Exhaust only systems perform the same function as open windows, however the discomfort and cold air sensation are not noticed because the air is infiltrating the space from many small areas. Whole house ventilation, or a heat recovery ventilator (HRV), exhausts contaminated air from our environment and directs that air through a heat capturing exchanger before exhausting it outdoors. Fresh clean dry air is then drawn from a healthy exterior location, pumped through that same heat exchanger, warmed up and then “supplied” back to the house. Over time exhaust only or heat recovery air exchange systems would eventually dilute or remove all the contaminated air from our tank. If our mechanical systems were used regularly, then particle/moisture accumulation would be controlled. If we are going to spend our winter indoors, and we understand the respirable suspended particles accumulation condition, then we must develop a means of ventilating/diluting our household air. Exhaust only or HRV mechanical systems do exactly that. Most homes are equipped with an exhaust only system (bath fan or range hood directed to outdoors). The issue then becomes the amount of time that system is in use. Noisy fans and impatient occupants may discourage fan use. If a 100 cubic foot per minute (CFM) fan is on for 15 minutes during your shower, you have exhausted (and therefore re-introduced) 1,500 cubic feet of air from your home. The average Canadian home contains approximately 20,000 cubic feet of air. Exhausting 1,500 CFM from 20,000 leaves 18,500 of stale air. Use your exhaust fans long enough to remove enough stale air to benefit the occupant. Heating system maintenance requires pre-season service and regular inspection. If your house is equipped with an air handling unit (AHU) or furnace that is a forced air type, you may wish to remove RSP’s (remember our fish tank) from the household air by means of filtration. Modern furnace air filters come in a number of sizes and varieties. A higher MERV (Minimum Efficiency Reporting Value) filter will remove smaller particles with greater efficiency. Too high a filter efficiency may restrict air flow through your furnace and cause mechanical problems. Too low a furnace filter rating (MERV 2) will not remove RSP’s whatsoever. Contact a certified Heating, Refrigeration and Air Conditioning Institute of Canada (HRAI) furnace/ventilation technician to help choose the most appropriate filter for your home. (www.hrai.ca) Switching your furnace operation from “auto to fan on” during winter months will “scrub the air” (furnace air will blow through the filter continuously filtering or scrubbing your home’s air). Temperature variation from room to room will be decreased with more air mixing throughout the house. Humidity control and monitoring will reduce the likelihood of condensation forming on cooler building assemblies. High interior moisture may condense on cooler building surfaces (inside walls and on windows). If you don’t monitor your temperature and relative humidity, you cannot control it. Purchase a couple of digital thermal hygrometers (about $25.00 each ) and place them around the home. If the temperature drops or relative humidity climbs above 60%, you should accelerate ventilation to dilute and reduce household moisture. It is important to weather strip and seal windows and doors. Houses with excessive air leakage cannot be effectively maintained. Leaky homes are controlled by the fickle whims of Mother Nature, with temperature, moisture and particle infiltration entering the home environment randomly. It is better to seal your home as much as possible, then to introduce effective controlled ventilation to address indoor air quality concerns on your terms, not Mother Nature’s. ** Closed windows and doors, measuring accumulation of house dust and particle require more flat surface cleaning and maintenance. Healthy hibernators must clean their environments more often to remain Healthy. Use low VOC (volatile organic compound) soaps and cleaners to maintain your home. Strong solvents and fragrances add to our environmental load. Clean your home with low fragrance/chemical content cleaners and damp mop more frequently to reduce respirable suspended particulate. If your home has carpets, vacuum floors and furniture with a true Hepa type vacuum regularly. It is possible to hibernate healthy. Your home may require some additional maintenance and monitoring. We cannot rely on open doors and windows for ventilation so we must utilize our mechanical systems to their full potential. Frequent filter replacement, more diligent housekeeping, and a new-found awareness for moisture control will provide your home and family with a safe and healthy environment until spring. Only 160 days until we can once again open our windows comfortably. In the meantime, sleep well in your healthy home…….zzzzzzzzzzzz. Written by: Shawn Rankin – Indoor Air Quality Ottawa Published by HealthWise Ottawa – Winter 2007/2008