Save a building, fight climate change

This column is an opinionby Hamilton-based writer Sarah Sheehan.For more information aboutCBC's Opinion section, please see theFAQ.

Reduce, reuse, recycle: adaptive reuse fits the sustainability mantra of the "three Rs," but all too often we overlook the green side of architectural conservation.

Whether it's a Gothic Revival church, a modernist Centennial project, or a contemporary design in glass and steel, a completed structure has a huge carbon footprint. 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.

Reusing old buildings is an easy way to reduce our carbon footprint, but first, our thinking about development needs a reset.

As Canadians, we can be cavalier about our abundance of resources, and existing buildings are no exception. Our construction industry relies on a cycle of premature obsolescence, demolition, and redevelopment. Older buildings are often seen as a liability, while much new development still operates on a "take, make, waste" model an extractive model for growth that's the opposite of sustainable.

A colossal amount of waste

Half the world's carbon emissions are from extractive industries such as mining; in the last 15 years, emissions increased the most from the extraction of non-metallic minerals associated with construction, such as sand, clay, and gravel. In fact, demand for concrete is so high that we're running out of sand.

For Canada, add deforestation and throwing away millions of tonnes of wood waste, including old-growth lumber, and you have a colossal amount of waste.

Acknowledging the up-front emissions involved in construction lets us see existing buildings not as future trash, but as valuable stores of embodied carbon. Also known as embodied emissions or embodied energy, embodied carbon refers to the total energy expended invested in a building's construction, from extraction of natural resources, manufacturing, and transportation, up to final completion of a new structure.

This carbon investment accounts for up to 50 per cent of a building's greenhouse gas (GHG) emissions over its entire lifespan, even for buildings constructed with the most sustainable, up-to-date methods and materials.

Embodied carbon was a hot topic in Glasgow last fall, as delegates met for the 26th UN Climate Change Conference (COP26), six years after the 21st edition gave us the Paris Agreement.

Joining the high-profile international delegates were members of the Climate Heritage Network, a group of sustainability-minded architects and urbanists like Carl Elefante, who coined the phrase, "The greenest building is one that is already built," and Mark Thompson Brandt of MTBA Associates in Ottawa, who often refers to "the common sense of recycling buildings."

A leader in built-heritage conservation as climate action, Brandt has advised on federally-owned heritage sites in Ottawa, including the House of Commons, the Connaught Building, even 24 Sussex Drive. His firm is also behind Building Resilience, an online toolkit for sustainable retrofits and rehabilitation of existing buildings. As Brandt told a post-COP26 gathering hosted by the National Trust for Canada, "Heritage conservation is environmental conservation. They're one and the same thing."

Built heritage, natural heritage: the climate emergency demands that we undo the established, artificial division between natural and built environments for a more holistic view of conservation, heritage, and sustainability.

Of course, re-thinking how we value architecture is something heritage advocates have been doing for decades. Yet the not-so-green status quo persists, based on postwar ideas that valorize unsustainable consumption. This lingering legacy amounts to a powerful incentive to waste.

Developers and regulators need to catch up

Since the Second World War, we've taken new development for granted as a sign of progress and prosperity. Think of the Crane Index, a simple tally of construction sites as a measure for growth. Susan Ross, who teaches at Carleton's Azrieli School of Architecture & Urbanism, emphasizes the growing imbalance: "By the 20th century, architects had completely bought into a real estate process that had made obsolescence its rallying cry, not yet recognizing how unsustainable the cycle of destruction and construction can be."

Yet Canadians already recognize the value of recycling architecture; it's developers and regulators who need to catch up.

Across the country, there is no shortage of examples of successful adaptive reuse. Converted industrial sites like Montreal's Usine C, Hamilton's Cotton Factory, and Toronto's Distillery District have become power centres for tourism and culture.

Even houses of worship, often seen as purpose-built and a hard sell for reuse, work brilliantly when repurposed. In Ottawa, there's Bluesfest HQ in a former Westboro church, nestled alongside new infill housing. In Saint John, New Brunswick, Cooke Aquaculture has their offices in a stunning former synagogue. And in Winnipeg, work has started on Augustine Centre, a hub to encompass arts space, childcare, and a shelter/drop-in program reimagining a century-old church for a greener future.

Architecture is a renewable resource. It's time we stopped seeing it through the lens of planned obsolescence.

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