Does a Home Energy Retrofit Deliver Results?
Energy consumption of this 1906 home has been cut almost in half through energy efficiency measures.
Photos: Matthew Wilson
Does a home energy retrofit deliver results?
Part 1
By Matthew Wilson
In August of 2023, we moved into our new home on Glebe Avenue. Like many Glebe homes, our house is old (built in 1906), large (2,300 square feet above ground) and in particular need of updating. From the finishings to the heating system, it was clear that we bought the proverbial fixer upper. But it was also an opportunity to make the house fit for the future, lighter on the wallet and better for the environment. This is my first of two reports on our journey.
We prioritized the building envelope and energy efficiency. Lowering the GHG emissions produced by a family of four living in Ottawa, one of the world’s coldest capitals, was a priority. We were motivated further by the availability of the federal government’s incentives for home energy efficiency. The chance to participate in a hybrid-heating trial offered by Enbridge Gas was also an exciting proposal.
In Canada, we use a lot of energy per person – more than in the United States, about the same as in Norway or Kuwait. Each Canadian uses the energy equivalent of about 20 barrels of oil a year. In China, it’s about three to four barrels. The energy we consume in the home is a big part of that.
Energy audit
Our journey with this Grand Dame of a house started with an energy audit. It showed that the house, at the time of purchase was consuming 264 gigajoules of energy per year. For comparison, one gigajoule is the equivalent of 39 litres of propane or two BBQ propane tanks. It also equals 277 kilowatts of electricity – it takes one kilowatt of electricity to power one 100-watt light bulb for 10 hours.
After our energy improvements, our closing audit indicated that we had reduced annual energy use from 264 gigajoules to 142. This was the equivalent of saving 244 BBQ tanks of energy per year. Rated “energy intensity” of the house dropped from .94 gigajoule per square meter per year to .50. We had cut estimated energy consumption almost in half.
Heating and cooling
In any household, about two-thirds of the energy consumed is the result of space heating, so that is where we focused our efforts. Our priority was to insulate. We removed the existing attic insulation and replaced it with spray-foam in the original third floor and attic. There had been no insulation in the knee walls of the third floor. Pre-insulation, summer on the third floor was miserably hot.
We then blew cellulose insulation into the existing exterior walls of the first and second floor. Cellulose insulation is the equivalent of finely chopped newspaper, and over 80 bales of the product were used in our walls. Only one room had been insulated in the house originally.
In the basement, we again used spray foam for the rim joist (where the wood frame meets the foundation). Some existing insulation had to be removed due to its poor condition. We received contradictory advice about the merits of applying spray foam to the stone foundation, so we haven’t. We may revisit this decision in the future. Instead, we completed repairs to the stonework.
We replaced two windows and one exterior door with new high-efficiency models. More windows will need to be replaced in the future but after further air sealing improvements, we set our eyes on the mechanical systems.
Previously, natural gas powered the furnace and hot water. There was no central air conditioning but a few window-box units. The Energy Factor of the existing power-vented, natural gas, hot water tank was .57, standard but far from the most efficient. The rented tank was 12 years old and was quickly approaching its 15-year life expectancy. The natural gas furnace, near end of life, was 92-per-cent efficient and had a huge output (136,500 BTUs) sized to keep an un-insulated home warm.
It was replaced with a hybrid heating system, including an air-source heat pump which provides heating down to -5 degrees Celsius in winter and air conditioning in summer.
When below -5, the other part of the heating system is a natural gas, on-demand, hot water heater which serves two purposes – it provides domestic hot water and hot water for the forced air furnace (a hydronic furnace). It is 98-per-cent efficient and is expected to operate at a 30-per-cent savings.
In the event of a power outage, the system will not operate. Just like a typical furnace in most homes, it needs both electricity and natural gas to operate. So, as backup, we also installed a natural gas fireplace, with no electricity needed.
Excluding the impact of insulating, the hybrid heating system (with smart controls) is estimated to reduce our home’s GHG emissions by 30 per cent. It was eligible for a $6,500 rebate from Natural Resources Canada (check what is available now because programs have changed).
The all-electric alternative would have been a cold-climate heat pump which can operate down to -30 degrees Celsius. A cold-climate heat pump might make a great deal of sense for many others.
Fingers are crossed for winter but since installation this spring, it has been operating perfectly. The house is more consistently heated and cooled and much more comfortable from top to bottom. On the outside, the unit is quiet compared to most air conditioners. I find the system control/thermostat to be very easy to use.
In next month’s issue, I’ll let you know what we did to reduce electricity use, present our savings thus far and offer a list of dos and don’ts for your home-efficiency journey.
Matthew Wilson is a Glebe resident who took on the challenge of improving the energy efficiency of a classic fixer-upper home.
