Zero House Goals – Zero Utility Costs & Net Zero Energy

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Key among the goals for Zero House are a pair of interconnected ideas: zero utility costs for the homeowner and net zero energy use for the building over its lifespan.

This building is not alone in the pursuit of this goal. Building code authorities and governments across North America are beginning to set ambitious targets for Net Zero Energy buildings, including Ontario and California. Climate change is the motivation for these moves to create buildings that generate as much energy as they consume on an annual basis.

What are we trying to achieve?
There is a lot to “unpack” when thinking about these goals. If climate change is the problem to be solved, the source of energy for a building is just as important as its energy efficiency. A building with poor energy efficiency that is powered with 100% renewable/clean energy is less of a climate change problem than a more energy efficient building powered with carbon-intensive energy sources such as coal, oil or natural gas. However, if low or zero utility costs for the building owner is the issue, then energy efficiency and the price of the source energy become the key issues.

Zero House at Endeavour Centre

We want a zero carbon footprint
Chief among the goals for Zero House is to have little or no carbon footprint over the lifespan of the building. This means pursuing a couple of key strategies:

  • Rooftop solar electricity (3.84 kilowatts) from BiPVCo that generates as much clean, renewable energy as the building will consume
  • Creating an all-electric home that eliminates the use of any fossil fuels on site
  • Specifying Bullfrog Power to provide the additional electricity the building needs when its solar panels are not able to meet demands

We want very low operating costs
Homes that are affordable to operate should be the norm, but they aren’t. Zero House will be, thanks to these strategies:

  • Rooftop solar electricity (3.84 kilowatts) from BiPVCo that feeds excess energy into the grid via Ontario’s Net Metering program
  • Very high energy efficiency to minimize heating and cooling loads
  • Very high efficiency appliances and lighting

Using energy modelling to achieve our goals
By creating a computer energy model for Zero House, we are able to predict the amount of energy required for heating and cooling the building as well as the amount of energy that will be generated by the rooftop solar electricity generation. We can also simulate the energy use for appliances, lighting and hot water. Achieving net zero energy use is a matter of ensuring that the energy being generated by the rooftop solar is equal to the energy being used in the building.

Zero House net zero energy home

Eneergy model output for Zero House

Hey, those figures don’t match!
As you can see in the graph above, the 4,487 kilowatt hours generated by the rooftop solar more than covers the expected loads for heating (460 kilowatt hours) and cooling (311 kilowatt hours). In fact, it will only take about 18% of the output from the rooftop solar to supply all the heating and cooling needs for the building. The remaining loads in the graph represent average North American consumption figures for hot water (1,799 kWh), appliances (2,792 kWh) and lighting (718 kWh), and assumes a family of three in the home. If the occupants use energy at the rate of a typical European family, the building will fall well inside the net zero energy requirements. This means that we’ve done all we can to make the building as energy efficient as possible, including low flow shower heads, LED lighting and the most efficient appliances available. It will be up to the owner to use these in a reasonable manner to be truly net zero.

The future is net zero
We applaud the efforts of governments and organizations (such as the Net Zero Energy Coalition) who are promoting the next generation of buildings that will produce as much energy as they use. We think it’s equally important to achieve this goal in conjunction with low embodied carbon and low toxicity, to create Zero buildings that minimize all harm to occupants and the ecosystem.