Innovation-July-August-2023

OPERATIONAL VS EMBODIED CARBON TQD accessed the two main carbon types: operational and embodied. Operational carbon emissions stem from the ongoing energy used to maintain a building. Embodied carbon refers to the carbon footprint accumulated during construction and design. Together, they are used to form a holistic life cycle analysis (LCA) of carbon emissions. While operational emissions are often addressed in the construction industry, embodied carbon requires deeper knowledge about the origins of materials and systems. As a result, mechanical, electrical and plumbing systems don't typically include embodied carbon calculations because data isn't available. For TQD, calculating electrical system embodied carbon emissions proved too difficult as it required detailed information about the raw material composition of components; much of this data is proprietary and not disclosed. In the end, the team chose to exclude electrical systems from their analytical scope. “Suppliers are not used to giving this information. They're not used to tracking this information,” said TQD sustainability lead Juliette Mollard Thibault. “As an industry, we haven’t wrapped our heads around how to do this.” For the components within their scope to evaluate, TQD calculates that it took 11,970 kilograms of carbon dioxide equivalent (kgCO 2 eq) emissions to build their house: a 74 percent reduction from a baseline standard of 46,352 kgCO 2 eq for a comparably sized house. The team was able to obtain some information through suppliers, many of whom were local to BC. Intentional supply decisions, such as sourcing wood from forests in BC, using a local heat recovery ventilation supplier, and reusing glass from heritage houses in Vancouver, helped them clearly calculate and further reduce emissions. “I think that the most important part is that we were having conversations with local manufacturers and suppliers about embodied carbon,” Mollard Thibault said. “We were asking for information, which is part of shifting the culture; you need manufacturers who have the relevant data and understand why it’s important to the designers.” CARBON SEQUESTRATION METHODS Constructing any building inevitably accumulates a carbon footprint. TQD's goal was to reduce carbon, especially embodied carbon, as much as possible. To do so, TQD used a biocomposite insulation, hempcrete, that the TQD team estimates will sequester up to 16 kg of carbon

dioxide per cubic metre. Hempcrete is a mixture of hemp hurds and lime that has been adopted across the world as a novel thermo-insulation method. Researchers are currently investigating its potential as a source of carbon sequestration through absorption of carbon within the lime binder. There are few commercial distributors or producers of hempcrete, so the students developed their own formulation, seeking to balance between insulation requirements and sequestration potential in their formulation. “The idea of bio-based insulative materials that also have thermal mass are really important for our building industry's future,” Mollard Thibault said. “But there are aspects of the calculation and understanding the material that need to be done.” OPERATIONAL EMISSIONS REDUCTION STRATEGIES To target operational emissions reduction, TQD placed solar panels on their south-facing roof, slanted at a 35–45-degree angle to optimize photovoltaic efficiency. The panels offset a large amount of remaining operational emissions; the team

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