The housing shortage has been well publicized across Canada, prompting the Ontario government, for example, to commit to building 1.5 million homes in the next decade. Meanwhile, concerns about climate change will bring ever more scrutiny on how those homes are built, with the aim of minimizing their contribution to greenhouse gas emissions, often referred to as the carbon footprint or output.

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Gord Cooke, President of Building Knowledge Canada, says that the industry is learning how to quantify that carbon output. In an article originally published in Winter 2021 in Better Builder Magazine, Gord details how builders can use this knowledge to make their homes greener—and attract a growing market of environmentally conscious homebuyers.

There are two main measurements of carbon in homebuilding: the greenhouse gas emissions related to the production of materials used to build a house, called embodied carbon emissions and the operational carbon emissions. It is essential to understand and optimize both.

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Material carbon emissions

The materials that make up a home all have their own carbon footprint: the extraction and manufacturing of each item creates emissions. It would be impractical for a builder to try to add all of these up but standard measurements are emerging and suppliers are calculating and declaring carbon emissions for their products.

The most carbon-heavy items in a typical home are concrete and concrete based cladding systems, followed by insulation, windows, and doors, then drywall. As a builder knows how much of these goes into each home, it’s possible to calculate the material carbon emissions associated with the majority of building materials used in the construction of a home. Software carbon calculators are available commercially to help with these calculations.

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Operational carbon emissions

Once a home is built, the carbon footprint of operating a home will have the greatest effect on climate change, as this factor is continuous for decades. Residents’ lifestyles will be a major factor in their emissions, but the efficiency of heating and cooling systems and the energy efficiency of the home can affect the operational carbon emissions by tonnes per year. Energy-modeling software, such as HOT2000, can be used to predict annual energy use and therefore operational carbon emissions.

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Available strategies

Building science is constantly innovating new materials, systems, and designs to improve energy efficiency, but the pressure to make homes greener is already on. Fortunately, says Gord, builders can make considerable gains through three cost-effective strategies:

• Get your concrete supplier to use a mix that includes 30% to 40% fly-ash or other supplementary cementitious materials. This comes at a very modest additional cost but can reduce embodied carbon by as much as 2.5 tonnes.
• Use an air-source heat pump, along with a smart thermostat that optimizes a dual-fuel approach to heating. This can reduce operational carbon by as much as 1.4 tonnes per year.
• Always aim to increase the home’s airtightness.

Naturally, the best ways to advance these strategies are constantly evolving, which means that builders should keep learning about the latest developments. Building Knowledge Canada can help builders and contractors understand how to make the best use of them. Get in touch to see how we can support your design and business goals.

Read the full article >

_{Originally published in Better Builder Magazine, Issue 40 / Winter 2021.}

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