Net Zero Heat
Net Zero Heat is
A building envelope designed for its specific climate so that no heat source beyond the sun is required to maintain a comfortable room temperature.
A new building philosophy
When searching for solutions to reduce home energy consumption, great focus is put on finding less harmful fossil fuels and creating more efficient heat distribution systems. These are great practices, but should be made secondary to harnessing and retaining the heat freely available from the sun.
While we look for more efficient ways to inject new heat into our homes, we often overlook the amount escaping. If the substantial investment made towards heat distribution systems is applied instead to a better building envelope, the result is a more efficient and resilient home, one that can also offer a better return on investment.
The Net Zero Heat service
By understanding how the most significant heat gains and losses occur, home design can begin with passive heat gain and retention as a priority. Diminishing returns on additional insulation means that at a certain point the benefits of adding additional insulation will stop, and from there you are best to add a certain amount of heat. Where that point is will always be different, and finding it is the premise behind the Net Zero Heat program.
The metric we base this service and rating system on is kWh per m² per year, meaning the amount of heating energy required per square metre to keep a home at a comfortable temperature during a full heating season.
The optimum level of performance for financial and ecological benefit depends on local climate, house dimension and orientation, window size and location, and the materials you choose to build with. In a very cold climate with limited solar exposure that may be 30 kWh; in a more temperate climate with full solar exposure, 0 kWh may be financially viable.
Ecohome performs a software analysis of building plans to determine how much and where gains and losses occur, offering designers a chance to modify plans before construction begins to allow homeowners the optimum return on investment.
The Net Zero Heat Challenge
There has yet to be a cold climate home built to stay warm with only passive heat gains, yet the ability to do so is certainly possible. The right design in the right climate could mean a house with no additional heat demand beyond normal interior gains and the sun, one that from the moment of occupation can have a lower monthly overhead than conventionally built homes. The additional investment needed for a better thermal envelope can be negated by eliminating the need for costly heating infrastructure and monthly heating bills.
So we put forward the Net Zero Heat challenge to all builders - work with us to build the first completely passively heated cold climate home.
Heat retention and balance
If your heat source is the sun, it will be on during the day and off at night. Net Zero Heat is achieved by retaining a sufficient amount of that heat, yet balancing it to avoid uncomfortable fluctuations over that 24 hour period, as well as storing excess heat for release during extended overcast conditions. Both passive and active heat storage systems can be employed to this end.
Climate and weather realities
It is impossible to predetermine weather patterns now and into the future, so regardless of a home achieving 0 kWh of heat demand through software energy modelling, we would always recommend the inclusion of some minor heat source to ensure comfort in unpredictable times. This may be in the form of one small centrally located heater, as simple as a baseboard, that will largely go unused.
A short history
Passive heating and cooling is an ancient building technique that was largely ignored until 1977 when a team of designers built the Conservation House in Regina, Saskatchewan, a revolutionary house that could be heated with a fraction of the energy that was required by conventionally built houses.
With heating requirements of 75 kWh per m² per year, the Conservation House introduced high performance building envelopes and passive heating to the modern building industry. Matching that performance serves as the entry point of recognition in the Net Zero Heat program.
The rating system
Homes that the Net Zero Heat program will recognize must not exceed 75 kWh for heat generation. That is half of what the average existing Canadian home requires for heat generation, estimated to be approximately 150 kWh per square meter per year.
Who can take the Challenge?
Anyone and everyone. No certification or credentials are needed to take the Net Zero Heat Challenge - if you can build it, we will recognize it. Builders, designers and architects can all contribute to market transformation, and help create a new philosophy in building design.
Learn more on our frequently asked questions page.