By Steve Jaques
How do you decide what to do to make your house more energy efficient? What are your retrofit options? How do you organize the retrofit work to ensure the best results?
There are many questions to answer when planning a retrofit and you may find yourself uncertain of how to proceed. Though you can get good advice from qualified contractors and other sources, it’s a good idea to be generally informed about your options so you’re aware of the possibilities for your particular house and the potential obstacles you might encounter.
There are three main retrofit categories: Basement, crawl space and slab-on-grade foundation retrofits can reduce the entry of soil gases, increase insulation, and eliminate moisture and mould problems.
First- and second-storey retrofits can add insulation, air barrier systems and vapour retarders in walls and roofs and replace or upgrade windows to reduce air leaks and increase thermal performance.
Mechanical system retrofits upgrade or replace your existing heating, ventilation or hot water systems so they work as efficiently as possible.
Before you start your retrofit, make sure you identify and solve any pre-existing moisture, air quality or structural problems, such as high humidity, poor indoor air quality, or cracks in basement walls and floors. If you don’t address these kinds of problems first, the retrofit may make them worse, wasting your time and money.
Energy efficiency retrofits can have unintended effects, even if there are no pre-existing problems. For example, once you have reduced air leaks, you may find that the indoor air seems stale because the amount of air entering and leaving the house has been reduced. Adding ventilation fans, or better yet a heat recovery ventilator, can help reduce or overcome this problem.
Once your house is more insulated and airtight you may also find that your furnace is too big to operate efficiently, so it may need replacing with a more appropriately sized unit. In addition, you could find that your fuel-fired heating appliances do not properly vent combustion gases when exhaust fans are in operation (a situation called backdrafting). You may have to provide sufficient make-up air to balance the exhaust systems.
Moreover, adding insulation to exterior walls and attics can lead to moisture-related damage to the building envelope if inside and outside sources of moisture are not controlled.
For example, before you add insulation to your basement, ensure stormwater drains away from the foundation and any leaks are dealt with. Ensure proper air and vapour barriers are provided when adding insulation to exterior walls.
Before starting your retrofit project, consult a qualified energy adviser, building professional, home inspector or contractor to ensure you choose the options that work best for your house and to identify and address any pre-existing problems. Often, you can choose corrective measures that not only prevent problems but also add value to the overall project.
Canada Mortgage and Housing Corporation has an About Your House factsheet called Understanding Energy Efficiency Retrofit Options for Your House. Download your free copy at cmhc.ca.