Creating a building that has a zero carbon footprint, uses zero toxins or uses zero net energy can be a challenge each on their own, but Zero House tackles all three of them at once, proving the concept is possible. The resulting house, executed by the Endeavour Centre and Ryerson University, contains no toxins, has no carbon footprint, no utility costs and no construction waste.

Zero toxin living space
Most homeowners seem to assume that some form of government regulation makes sure the building products in their homes are not toxic, but this is not the case. In fact, there are really no standards or regulations applied to the toxicity or chemical content of building materials, except in the cases of well-documented pollutants like asbestos and lead.

In the building of Zero House, the architects used the Living Future Institute’s Red List Chemicals, which came down to eliminating nearly all foam insulation materials, manufactured wood products, vinyl windows, most brands of paints, etc. This sounds like a lot, but there are alternatives for materials containing these questionable chemicals, such as fibreglass, plywood, natural oil finish for the floors, cork flooring, and much more.

Zero carbon footprint
During the harvesting, processing and manufacturing of building materials, there are always greenhouse gas emissions involved. Some materials have high emissions, and others low.

Calculating a building’s carbon footprint involves figuring out the weight of each material and then applying the appropriate embodied carbon factor. With Zero House, this comes down to about 75.25 kg of emissions per square metre, which compares very favourably with the same house built to typical code standards, which would emit 134.8 kg per square metre.

However, plant-based materials, such as hemp, cork, bamboo, mycelium, etc., actually sequester carbon, as they absorb CO2 during their life. Normally, this is released into the atmosphere when the plants degrade or are burned. But when these materials are included in a building, the CO2 is sequestered. Zero House uses a wide range of carbon sequestering materials, only using 3 materials that do not sequester carbon. In total, the Zero House sequesters 32.26 metric tons of CO2!

Most of the CO2 is sequestered in wood, but the house also includes “waste” fibres (straw, recycled wood fibre, recycled drink cartons, recycled newsprint, cork) that would have otherwise cycled directly back into atmospheric CO2.

Zero net energy
If climate change is the problem to be solved, the source of energy for a building is just as important as its energy efficiency. After all, a building with poor energy efficiency that is powered with 100% renewable 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.

This led the architects to aim for a house with zero net energy use, as well as one with low operating costs. Using rooftop solar electricity and by making the house all electric, the need for fossil fuel was eliminated, while efficient appliances and lighting, as well as energy efficiency gives the house low operating costs.

Zero construction waste
While it was not technically zero, in the construction of Zero House, there was hardly any construction waste, less than 10 kilograms (22 pounds). The team achieved this by using a lot of chemical-free, natural materials that are simple to re-use, recycle or compost. They also didn’t buy materials with a lot of packaging and made sure that the packaging that was there was recyclable. The site crew was also waste-conscious, minimising the use of food wrappers and take-out containers. Lastly, they separated all waste on site.

The Zero House is a 1-to-1-scale model and was constructed in 2 weeks for display at the EDITdx Expo for Design, Innovation and Technology in Toronto (28 September – 8 October 2017).

Photos: Endeavour Centre