It’s cool to be green
By: Greg Labbe - June 15th, 2007
So you want to help the planet this summer by using your air conditioning less? The best thing to do, of course, is to turn it off! But that’s wishful thinking. At least, it probably will be until all our homes are super-insulated, well-sealed, with increased thermal mass indoors, heat-reflecting windows and big shady trees on south and west faces. Then we wouldn’t need AC to be comfortable.
Unfortunately, old houses are nowhere near this standard and many new homes have lots of big windows on the south and west elevations—without awnings or trees to block the sun warming up the indoors.
If you’re shopping for an air conditioner, keep in mind that its efficiency is measured in SEER Ratings, where every one SEER point increase represents about a 10% savings in energy cost. Aim to get a unit with ozone-friendly refrigerant R410A, and avoid HCFC22 and R22.
Here are some other things you can do to keep cool and minimize your impact on the environment:
• The first rule of thumb in heating and cooling is make sure your home’s thermal envelope performs well (it helps to reduce air leaks and have good insulation) and keeps the outdoor elements out! For good advice on making your home more efficient in summer or winter, get an energy audit done by a qualified professional. For a list of companies that provide energy audits, go to http://oee.nrcan.gc.ca/residential/personal/new-home-improvement/contact-advisors.cfm?attr=4 In Toronto, you can call Green Saver www.greensaver.org 416-203-3106 for a professional assessment and to get registered into the federal government’s rewards program.
• Insulating and air sealing your house can improve your comfort and save you money. With central air, make sure the outdoor compressor’s fins are free of dirt and leaves and don’t forget to take that cover off! Clean your furnace filter in summer for optimal air flow. If the unit doesn’t perform as well as it did in the past, have a qualified HVAC technician confirm that there’s an adequate level of refrigerant in the system.
• While running your AC, close all windows to keep out humidity and hot air, and ensure the curtains or blinds are drawn to keep out the sun’s heat.
• With a window unit, keep it shaded from sun (sunlight heat reduces performance by up to 15%). Keep the filter clean, and replace it with a new one when necessary. If it’s pre-1992, aim for the highest SEER you can afford. TIP: Home Depot is giving $25 for any AC returned on weekends in June. For more information, go to http://www.cleanairfoundation.org/keepcool/index.asp
• Plant a tree for shade on the south and west sides of your home. If you have a flat roof membrane, paint it white with an approved eleastomeric paint, which goes on as a breathable film, and releases moisture that builds in walls.
• If you can’t wait for that tree to grow, install awnings or exterior shutters on for south and west facing windows that get lots of sun.
• To keep smog levels down, don’t use your AC at peak times—between 7 a.m. and 10 p.m.
• If you’re considering installing a new AC and don’t have a large air return grill on the top floor of your house, consider installing a split system. These tend to work very well in tall, skinny, old houses as they convert hot, moist air trapped on the ceiling of the top floor to cool air—which then trickles on down the house. Resist installing a cooling system in your attic. They tend to be less efficient because of the high temperatures in the attic. Just think of how hard your refrigerator would have to work if you put it in the attic on a hot, sunny day.
• Look for an EnergyStar-qualified AC when buying a new unit (14 SEER). Pre-1992 models are likely between SEER 7 - 8 (consider a replacement if you have one), and post-1992 models run 10 – 17 SEER. (TIP: Many provincial power regulators have rebate programs for this. For example in Ontario, you can get a $500 rebate coupon from OPA. For more information, go to http://www.coolsavingsrebate.ca/ Check too with your local utility for incentive programs. Toronto Hydro, for example, offers $25 credit if you sign up for their peak SAVER AC. http://www.torontohydro.com/electricsystem/powerwise/peaksaver/index.cfm).
• If you’re designing a new house, consider passive solar design. Get more information from http://www.nesea.org/buildings/passive.html.