With the federal government kicking off a design competition to revitalize the Prime Minister’s residence at 24 Sussex Drive in Ottawa, a local architecture firm is already on record with a concept for a “radical rehabilitation” to make the building a showcase for heritage preservation and “zero-carbon sustainability performance.”

The storied building described by CBC as “Canada’s most famous fixer-upper” has been vacant of any human occupants since 2015 and an empty shell since 2023, with all its furnishings removed. But Prime Minister Mark Carney announced June 26 that renowned Canadian architect Moshe Safdie will chair the jury for the redesign, and pitched a public fundraising campaign at the end of June to help cover the cost of the project. On Aug. 21, Public Service and Procurement Canada (PSPC) opened preliminary bids for a design/build firm to get the job done.

The news landed almost a decade after Trace Architectures, a small design firm based in Ottawa’s Sandy Hill neighbourhood, published its unsolicited proposal [pdf] for the “adaptive reuse” of 24 Sussex, complete with “heritage preservation, a new ‘official wing’ addition, and zero carbon sustainability performance.” The concept called for a “‘deep green’ sustainable rehabilitation of the historic place,” with features like:

• Onsite energy generation and efficiency;

• Passive ventilation for some heating and cooling;

• Deliberate use of stone and concrete to absorb and store solar heat;

• Airtightness;

• Durable masonry;

• Water efficiency;

• Sustainable rehabilitation of the existing site, including reuse of some existing building elements.

“Our firm took umbrage at calls for dumping the venerable but vulnerable old house into landfill,” said Trace’s then-senior conservation architect and urbanist Mark Thompson Brandt, now the firm’s partner emeritus. “Instead, we found the value in the existing, leveraged embodied energy and embodied carbon, and returned the place to what it was primarily intended to be, through all its years of changes over time: A single-family home.”

In the Trace Architectures concept, “both the preserved historic building and the modern structure are developed to the exacting standards of zero carbon, showcasing the current Canadian leadership in that realm, and together provide a real ‘educational workshop’ in Canadian environmental technologies, materials, and assemblies,” Brandt added. “The heritage conservation and the sustainability achievements form an ensemble that simultaneously covers both natural and cultural conservation.”

Mould, Asbestos, and Rodents

Conversation about the condition of 24 Sussex has carried on in fits and starts since the 1990s, when the home first began showing signs of decay, the Globe and Mail writes. “A 1995 break-in, during Jean Chrétien’s occupancy, also raised concerns about security risks [and about occupants successfully wielding soapstone sculptures—Ed.]. But successive governments, wary of the political risk that might come with costly renovations, held off on dealing with the issues, which ranged from mould and asbestos to rodent infestations. In 2023, the National Capital Commission gutted the building, removing its furnishings and finishes.”

But “24 Sussex Drive is more than a residence; it is an enduring symbol of Canadian democracy and an important part of our architectural and cultural heritage,” Johanna Hurme, president-elect of the Royal Architectural Institute of Canada (RAIC), said in June. “The opportunity to renew it comes only once in a generation.”

In its own release in late August, RAIC laid out a two-step bidding process for a firm to both design and build the project. After an initial Request for Qualification (RFQ) from PSPC identifies up to seven qualified bidders, the federal government will invite full bids in a request for proposals (RFP) to the shortlisted design teams. RAIC will play a specific role: “bringing independent architectural expertise, established competition practices, and professional design evaluation into the procurement framework established by Canada.”

The jury chaired by Safdie will be responsible for evaluating the full design proposals, RAIC added, with federal officials making the final procurement decision.

In an email, RAIC said the goal of the 24 Sussex project “is renewal and rehabilitation, preserving its defining heritage character while restoring the property as a secure, accessible, sustainable, and functional official residence.” The spokesperson did not answer questions on:

• Whether the bid documents would treat sustainability, energy use, water consumption, operating costs, emissions performance, or embodied carbon as rated criteria;

• Any foreseeable challenges balancing sustainability or heritage criteria against the building’s operational and security needs;

• Any similar projects elsewhere that have addressed the same mix of criteria.

CBC reports that Canadian building materials and Indigenous participation will be conditions for successful bidders. The bid documents say the government is looking for a “world-class design vision” for a rehabilitated residence of “national and historical significance.”

However, The Energy Mix has learned that the decision to make 24 Sussex a design/build project has generated disappointment in the design community, with some would-be bidders worried that the process itself will draw focus away from producing the best design for the site. There’s also a concern that the design/build requirement and the size of the overall project, in the range of $50 million, will keep smaller firms out of the running while favouring bigger bidders with more established business relationships.

Keep the Building, Save Embodied Carbon

Trace Architectures Principal and Senior Architect Chris Warden said the firm previously applied its focus on embodied energy and carbon in existing buildings on a project to rehabilitate and adapt the Sir John A. MacDonald building, across the street from Parliament Hill. It was a time when building sustainability and conservation was “slanting away from new building materials and towards the fact that the embodied carbon or up-front carbon is already there, so why not use it?”

It’s a line of thinking that has been “percolating” among designers in Canada and elsewhere, he told The Mix in mid-July.

“If you keep the building you’re going to be further ahead,” he said. “As we push away from dirty energy sources, that embodied carbon becomes a bigger slice of the carbon pie.”

Part of that has to do with discovering, or rediscovering, the efficiency or sustainability features that were often built into older structures and forgotten over time.

“In some cases, buildings are inherently inefficient,” he said. “In other cases, it’s less about the building itself and more a matter of how it’s been altered over its lifespan.” Warden’s description of what happens next almost sounded like listening for the voices of architects long past.

“You walk into a building and you look around, and something doesn’t feel quite right,” he said. “This is not what they would have done at the time. You peel back layers, and you can often find solutions in how the thing was built in the first place: Interior walls with transoms that are operable, or cross-ventilating, operable windows…

“There are lots of strategies you can employ that are pretty straightforward as long as you’re looking for them,” he explained. But “part of the challenge is justifying them, because they’re kind of implicit. You walk through and look at the building and how it would have been designed,” but those workable past design features sometimes look insignificant against an “operational mechanical something” that gets bolted onto the original design.

But ultimately, the design process for a heritage building should begin with “just trying to understand the why. As a heritage architect, that’s one of my favourite things.”

‘The Most Sustainable House in the Country’

For 24 Sussex, Trace’s concept began with “retaining the existing building, looking at ways to dismantle the existing pool pavilion and introduce renewables.” The plan included wind turbines for microgeneration, solar shingles or panels, and rainwater harvesting on the new pavilion roof, among a collection of other features.

“For lack of a better way to say it, this should be the most sustainable house in the country, period,” Warden said. “There’s absolutely no reason why that isn’t the case,” partly because “so much of this is not new. Most of it just needs to be rediscovered [and] it’s not complicated—in fact the simpler you can make it, the better it’s going to be.”

He added that “I don’t like to look at our neighbours to the south and what they’re up to with their house, but the way that proposal is framed has a very specific intent. If you spin it around and think about 24 Sussex, with a bit of broader, more inclusive thought around what it should be and how it represents the country, it’s a really interesting challenge, especially on a site like that.

“But regardless of what lands there, there’s no reason it shouldn’t be net-positive. I don’t think that’s too high a bar for this size of project.”