Despite energy-efficiency initiatives, CO2 emissions from buildings and construction reached an all-time high in 2021. We need to pay more attention to alternatives, such as conservation, retrofits, deconstruction, and a circular approach to building construction and maintenance.
“Demolishing an existing building, throwing it away in a landfill, is a staggering act of conspicuous consumption. And yet this destructive, extractive approach to Canada's built heritage has been normalized over generations.” – Sarah Sheehan [CBC]
The heritage community has for many years focused on the historic value of buildings facing demolition, while opponents argued that the new buildings would be more energy-efficient and sustainable. However, this argument fails to take into account upfront carbon emissions, which are far greater in a new build than in renovation.
The restoration of Vancouver’s iconic Canada Post building combines heritage conservation with an energy retrofit. “The Post project will save approximately 25,000 tonnes (27,558 tons) of carbon by retaining the existing structure of the building. The office buildings will be designed to Leadership in Energy and Environmental Design (LEED) Gold Certification, and many energy saving measures will be employed during operation, including waste heat recovery, passive solar shading, light shelves, and an energy efficient building envelope.”
The purpose of a space can change dramatically as in the case of an art deco Jewish centre in Calgary that has been repurposed as condos and a pumphouse now occupied by two theatres.
The Regina Public Library board has voted to tear down the existing building and construct a new one due to structural and repair issues. Friends of the Regina Public Library are advocating to retain and retrofit the existing library and have assembled a wide array of resources to support their case.
New Builds & Retrofits
“People want to put solar panels on the roof, or point out how they are using better insulation. Those are great, but it’s also really important to think about how much of a difference you can make by building something that is reasonably sized, using a reasonable amount of material.” – Professor Shoshanna Saxe [U of T Engineering News]
During the initial construction, Sundance Housing Co-op in Edmonton chose 2x6 walls (exceeding the building code) rather than closet doors. Forty years later, the townhouses needed new siding and they opted for increased energy efficiency with fibre-cement siding, new windows and doors, and air source heat pumps. The renovated units use one-quarter the energy of the unrenovated units and will soon use 100% renewable energy – all at a fraction of the cost and the emissions of a new build.
To keep new construction as sustainable as possible, keep it small and, perhaps more surprising, avoid basements as they require a disproportionate amount of material.
Deconstruction & Reusing Materials
“Our vision is a construction industry where deconstruction and remanufacturing replaces demolition and disposal.” – Adam, owner of Unbuilders [Unbuilders]
Unbuilders is a BC company. Their former carpenters, roofers, framers, and tradespeople disassemble homes and upcycle the elements rather than simply destroying them. Each project diverts 50 tonnes of waste and salvages 10 tonnes of lumber.
ABMT Wood Solutions dismantles grain elevators for less than it would cost to demolish them and then sells the aged wood for reuse in a variety of projects ranging from feature walls to flooring.
Up to 37% of Victoria, BC’s landfilled material is generated by the construction industry. They have introduced a bylaw requiring construction companies to pay up front for a demolition permit. “If they salvage at least 40 kilograms of wood per above-ground square metre of floor area during deconstruction, they will get all the money back.” A similar bylaw is already in place in Vancouver.
Reusing the salvaged materials is challenging as so many materials can’t be broken down. The emphasis is slowly shifting to component parts that can be disassembled or composted. Michael Baars runs a circular demolition company and refers to himself as an urban miner. His crew disassembled a 14-storey office tower in Amsterdam. He says, “we should design man-made objects and products in such a way that we’re not destroying the resources, but that we’re basically borrowing them for a certain amount of time …. and that we can take them out in their pure form and put them back into the system.”
“The circular economy offers practical opportunities for a transition to a waste-free, resilient economic system … The essence of the circular philosophy is the need to move from a linear ‘take-make-waste’ economy, to a circular economy. In this approach, products will last longer, we will use materials in a never-ending cycle and we will get the most out of existing assets such as buildings and machinery.” [ABN AMRO]
Amsterdam’s Circl building employed 5 different circular construction practices:
1) use recyclable/reusable materials and avoid use of raw materials (bricks and tiles made from recycled materials and bitumen-free roofing);
2) deliver a service instead of a product (Circl’s elevator is owned and maintained by the supplier on a pay-per-use basis);
3) maintain and extend lifetime through smart maintenance, repairs, upgrades and renovation (buildings are constructed flexibly and adaptively to simplify maintenance, renovation, or a change of function);
4) combat underutilization or surplus capacity by sharing products or assets and optimizing their use (tools, people, and knowledge); and
5) use waste from used products and the production process to make new raw materials (reuse materials already on site, residual wood from the main load-bearing construction used for the interior, load-bearing elements designed large enough to be reused in a future building).
Building on the Past to Sustain the Future [Canadian Association of Heritage Professionals]
Practical Guidelines for the Sustainable Rehabilitation of Existing Buildings in Canada [Building Resilience]
Material Emissions Benchmark Report for Part 9 Homes in Vancouver [Builders for Climate Action]
How to Recycle a 14-Storey Office Tower [New York Times]
The San Marino Declaration for Sustainable Architecture [The Earthbound Report]
Photo credit: Prague https://www.flickr.com/photos/apmckinlay/29888679436
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