"Our Journey to Net Zero" - How a Lethbridge family constructed their high performance home
“Why aren't more builders building this way?”
Submitted by Brian Sexton, P.Eng.
Industrial Approvals Engineer
Brian is an Industrial Approvals Engineer in Lethbridge. His role involves ensuring industry adheres to the Environmental Protection and Enhancement Act in protecting Alberta’s air, soil and water. His care for the environment doesn’t stop when he leaves work – in 2016, he and his wife built Lethbridge’s first Net-Zero Ready home.
Our journey to Net-Zero began when my wife and I moved in 2011 from our first home to a newer, similar-sized home. After a few months, we were shocked to find that our energy bills had more than doubled. After a few years of tolerating the higher costs, we decided to build new and to a high energy efficiency standard.
After a bit of research, we learned that a Net-Zero home produces as much energy as it uses over the course of a year, and we looked into Net-Zero construction. We could not find a local contractor willing to work with us on this project, so we secured a lot in a new area of Lethbridge, and I acted as the general contractor for the build.
After a year of careful planning and working with an experienced Edmonton-based Net-Zero home designer, we broke ground in September 2016.
The most important part of a Net-Zero house is the building envelope. In our case, the walls are 12 inches thick, with dense-pack cellulose fiber insulation. The attic has 24 inches of loose-fill insulation. All windows are triple-pane with argon gas, and extra steps were taken to ensure the house was well sealed against air leakage. The house includes a heat recovery ventilator that brings fresh air into the home and captures some of the heat from the exhaust air. All light fixtures are LED, and the appliances are high efficiency –including an induction range and ventless dryer.
To use a gas furnace in this type of home would be overkill, so there is no natural gas connection to the house. All heating is by an electric baseboard heater in each room, and hot water is provided by a regular 60-gallon electric hot water tank.
When it is -33 degrees outside, the house requires 7.75 kilowatts (kW) to stay warm. That's like using five hair dryers to heat a house totaling 2,450 square feet. In the summer, the house stays cool and does not require air conditioning. A nice feature of the home is that there are very few moving parts: no furnace or air conditioner to break down, no expensive geothermal and no noisy heat pumps. The extra insulation provides soundproofing and makes for a very quiet and comfortable home.
After the first two years of living in the home, our average energy bill was $105 per month, and our average usage was 773 kilowatt hours per month. In December 2018, we purchased a used electric car, increasing our monthly energy bills by about $45 due to “fueling" our car for approximately 1,600 kilometres of commuting each month.
When we totaled up the cost of the build, we determined that our home was built for the same cost per square foot as a standard, code-built home. This is after including a builder's markup of 20%. So why aren't more builders building this way?
Our journey to Net-Zero continues. Our next step is to install a solar array on the roof. A 10kW system is all that is needed to offset our total annual energy use. This stage of our project will depend on available solar funding, but once complete would make ours Lethbridge's first Net-Zero home.
Brian would be happy to share tips and information on Net-Zero building. You can email him at firstname.lastname@example.org
or check out the Lethbridge Net Zero House Facebook Page by clicking the below button: