Three Energy Efficient Homes: The Edmonton Experiment
Three adjacent homes in Alberta’s capital have been equipped with different energy sources, with the goal of identifying the optimal net-zero efficiency system
Belgravia Green in Edmonton is an innovative project where three families built three net-zero homes in a row. It all started when Jeanette Boman and Kevin Taft advertised in a community-league newsletter looking for two other families to join the project.
After 40 interviews they selected Les Wold of Effect Homes and another family as their partners.
Today two attractive, modern infill net-zero ready homes bookend a net-zero show home with a large solar array in the middle. All three homes feature different heating systems.
A net-zero home is a home that produces as much energy as it consumes.
While each home has a different heating system, all three homes are very airtight, super insulated and have triple-pane windows. This gives Effect Homes the opportunity to see how different heating systems work for future net-zero projects.
All three homes are gas-line free. The three heating systems have replaced the typical gas-fired furnace.
House #1: Geothermal heating
In the first home the heating comes from a geothermal heating system that uses a ground-source heat pump. Think of a ground-source heat pump as a reverse refrigerator.
A refrigerator uses a heat pump to move heat from inside the fridge to outside the fridge to maintain a pleasant fridge-like temperature. A geothermal system uses a heat pump to move heat from the ground into your house to keep it at a pleasant temperature for humans.
Upfront costs are high for geothermal: the system for this 1,540-square-foot home costs about $40,000. However, without a gas line and monthly gas bills, the operating costs tend to be lower – on par with natural gas when gas prices are really low and much better at other times. There is also a second potential major benefit – you can run it in reverse and use it to cool the home in the summer.
This home reached an EnerGuide rating of 91, which means the home requires little external energy.
House #2: Air source heat pump
An air source heat pump is the same as the geothermal system with a major difference. Instead of pumping heat from the ground into the house it pumps the heat from the outside air into the house.
Think of it as a reverse air conditioner. Instead of pumping the warm air out of the house for cooling you’re pumping warm air into the house for warmth. It does this all the way down to minus 15 degrees. After that it uses electric heating to help out on cold winter days.
This system costs about $12,000-$13,000, about the same as a gas furnace with an air conditioner. The operating costs are about 30 per cent less than a conventional system.
Fifty-eight solar PV modules power the house and export electricity to the grid when it produces more than the house needs. These cost about $58,000.
This net-zero show home gets 30 per cent of its heat from passive solar design. Large south-facing windows let the sun shine on a very comfortable concrete floor to store the heat.
The mechanical room in this otherwise whiz-bang home is remarkably empty. The air-source heat pump and electric heaters look like a conventional furnace. There is also an on-demand hot water heater and a hear-recovery ventilator to provide lots of fresh, preheated air to the home.
This home has a pending EnerGuide rating of 100.
House #3: Baseboard heaters
These are simply electric heaters that are scattered throughout the house. While not the most cost-effective form of heat, this house has double stud, R56 walls and an R100 roof. While the other houses are super insulated, this house is super-duper insulated.
This system costs very little up front, about $4,000. The costs to operate are around double that of natural gas, but this home is also solar ready so the electric heaters will eventually get their electricity from solar panels.
This home has an EnerGuide rating of 90.
It costs about 7 to 8 per cent more to make a home net-zero ready. The secrets of net-zero, according to Les Wold, are creating an energy-efficient envelope, use of passive solar heating and adding an energy supply such as solar.
While the two near net-zero homes don’t have solar modules at the moment they are solar-ready.
Troy Media columnist David Dodge is the host and producer of Green Energy Futures, a multi-media series presented at greenenergyfutures.ca.