en.Wedoany.com Reported - A case study on three preservation-focused building retrofits in Halifax, Montreal, and Vancouver shows that such adaptive reuse projects can cost less than demolition and new construction, while also having lower embodied carbon emissions.
The report was published by the Canadian Association of Heritage Professionals (CAHP). Board Chair Adam Hatch stated that the conclusion was expected, but the extent to which existing buildings outperform demolition/new construction was "somewhat surprising." Hatch noted that quantifying this from a life-cycle carbon and life-cycle cost perspective provides significant value.
The selected buildings include a mid-century modern office building in Halifax, a former textile mill in Montreal, and a historic residence in Vancouver. None of these buildings are designated as heritage structures, but they are considered to have intrinsic value within their communities. Instead of deep renovations, the CAHP case studies adopted a preservation-led approach, prioritizing the reuse of existing materials and structures to limit construction intervention. Hatch believes that without more flexible codes, preservation-focused retrofits will be difficult to advance. CAHP points out that current codes do not clearly specify how builders can meet performance standards. This leads risk-averse developers and contractors to view retrofits as uncertain and avoid them, while demolition is seen as a controllable option. By providing flexible pathways for code compliance, builders would have more options when dealing with "unexpected" issues during retrofits, thereby reducing project risk.
Hatch noted that another challenge is the industry's general perception that old buildings have low value. He called on the industry to view existing buildings as opportunities rather than burdens. For the Halifax mid-century government office building converted into residential units, the report evaluated three scenarios: full retrofit, retrofit with addition, and demolition followed by new residential construction. The results showed that due to the retention of concrete structures, foundations, and envelope components, the retrofit scenario had "significantly lower" embodied carbon emissions than the new construction scenario, while also being less costly than demolition and new construction. Similar conclusions were drawn for the early 20th-century textile mill retrofit in Montreal. All three cases demonstrated that retrofitting is more economical than demolition and new construction. Hatch added that retrofit projects can be completed in a shorter time frame. This is supported by the Halifax project: the retrofitted building has already begun leasing units, while a similar government office building purchased simultaneously across the street for demolition and new tower construction remains a construction pit. Preservation-led adaptive reuse can also accelerate approval cycles, as the building's form, scale, and massing are already established.
Hatch revealed that governments at all levels have shown significant interest in the CAHP report, with many municipalities expressing keen interest in how to best apply building codes for retrofits and utilize existing building stock. CAHP's next step is to submit the research report to policymakers responsible for code standards and to engage with government agencies, private owners, architects, designers, engineers, and homeowners. Hatch stated that to prepare for the growing retrofit industry, builders and related personnel should educate themselves and train workers on which materials and structures can be reused. The CAHP chair noted that large companies are beginning to shift from new construction to renovation, and this transition is expected to continue, requiring everyone to master renovation techniques. He emphasized that approximately 75% of today's buildings will still exist in 2050, so both for achieving climate goals and practical reasons, these existing buildings must be improved and reused.
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