Our family has lived in the Pocket for almost 30 years. As our kids moved out and living arrangements changed, we were preparing to renovate our semi-detached house into two units. It seemed like a natural time to undertake an energy retrofit as more members of our family are becoming engaged in climate action.
Large parts of our house hadn’t had energy improvements since the house was built over 100 years ago, including uninsulated brick walls and a drafty front door. Air sealing and more complete insulation with contemporary materials were obvious choices. To further reduce our greenhouse gas (GHG) emissions and improve home comfort, we also converted the second and attic floors to a new, all-electric ductless heat pump heating system and selected an electric induction stove and dryer.
We chose to air seal and insulate most of the house from the exterior. This allowed us to live in the house during the renovations, and to reduce loss of interior floor area by eliminating the need for new stud wall cavities to hold insulation. The exterior retrofit allowed us to create a continuous air barrier and thermal blanket around the walls. We chose Blueskin air barrier because it is a durable, self-adhered membrane that acts as air, vapour, and water resistive barrier. Adhered in sheets directly to the brick, it creates a continuous barrier less prone to tears and punctures, and easier to install properly than conventional house wrap. For the insulation, we chose Rockwool mineral wool because it is moisture resistant and has much lower embodied carbon than foam insulations (i.e fewer GHGs are produced from its extraction, manufacturing and installation). Based on some calculations done by our son, we decided that 3” of exterior insulation was a good balance between cost and energy savings. For the cladding, we chose Hardie fibre cement board that maintains the home’s classic look and won’t need to be replaced for decades to come. The exterior air sealing, insulation, and overcladding cost about $25,000.
We love the old brick character of the house and we felt mournful about covering it all up. As a compromise, we insulated the front wall of the house from the interior so that the brick can still be seen from the street. This approach is less thermally efficient, but still a lot better insulated than the house was before.
Other improvements included air sealing and insulating the basement walls and slab while we were renovating the basement into a new floor plan. The new ground floor and basement heating system has a heat recovery ventilator, which provides fresh outdoor air to these floors while recovering heat from stale exhaust air. This has helped get rid of that damp ‘basement smell’. We also completed the conversion of all lighting, excepting an antique chandelier, to LED fixtures. While the heating for the lower levels and hot water throughout are still supplied by a gas boiler, we chose a high-efficiency condensing unit.
The second/third floor unit is heated and cooled by an all-electric, Mitsubishi cold climate air source heat pump with three heads – one in the back kitchen, one in the front living room, and one in the third floor room. The heat pump operates 2-3x more efficiently than a gas furnace. We like that we can control the temperature setpoint of each heat pump head, so we only heat the rooms we are using while the other rooms are “setback” to a lower temperature like we would do overnight.
We are glad to have hired contractors who were recommended by Paul Dowsett – our friendly neighbourhood Retrofit Coach. They understood the building science fundamentals to exterior retrofits and chose all the right materials for the job. Common misconceptions we’ve read online about exterior insulation could have created serious moisture problems in the walls. Additionally, we knew that for air sealing to be effective, we needed high-quality trades with good attention to detail.
Based on our utility bills, we calculated that we reduced our gas consumption by 37% in the 8 months since the renovations were completed. This represents 930 m3 of natural gas, or the equivalent of taking a car off the road for 5 months of the year. We are looking forward to having a year’s worth of utility bills to compare our savings. These savings were calculated during the heating season (August – April) and do not factor for annual differences in temperature before and after the retrofit. Our utility bills are difficult to compare before and after the retrofit, as adding an extra dwelling unit increased the functionality of the home and added some additional electrical and hot water loads.
When it comes time to replace our roofing, the next step of our home energy improvements will be to air seal and insulate the flat roof, as well as add further insulation to the peaked roof. Making the air barrier continuous from the wall to the roof will make a big difference in decreasing air leakage from the home, and the insulation will be especially helpful in keeping the third-storey office cool during the summer months. Installing photovoltaic panels on the flat roof would also further the conversion of the second floor unit to a low GHG residence.
Undertaking these home energy improvements was an easy addition to our renovation plans. While some of the work was made easier by the other renovations, most of these retrofits could have been done at any time. The air sealing and insulation has made our home less cold and drafty, and we conserved energy this winter, putting fewer GHGs into the atmosphere, doing our small part to reduce climate change, reflecting our family’s values.
