At first glace, affordable housing and net-zero energy use make for strange bedfellows. How do you reconcile the modest rent of the former with the expensive design of the latter? Turns out, they go together like a hammer and a nail.

“It’s counterintuitive (in the long term) to think that simply driving construction costs down will make housing more affordable,” says Michael Kabalen, executive director of the Affordable Housing Association of Nova Scotia (AHANS). “The reality is that the number one impact on rent is the carrying cost of an asset, not the construction cost.”

And net-zero energy is about as low as carrying costs get. Buildings efficient enough to produce the power they consume are more expensive to erect, but relatively inexpensive to maintain, especially if you factor in utilities, which AHANS includes with rent.

“Having certainty in cost is one of the best ways to have certainty in rent,” says Kabalen. “What we’ve seen is that the initial upfront costs of building to net-zero, in the end, are cheaper than ongoing increases in utility costs from not building to net-zero.”

AHANS is a registered non-profit constructing and maintaining affordable housing across Nova Scotia, but their first foray into net-zero didn’t come until 2022. That year, via the federal government’s Rapid Housing Initiative, they constructed two apartment buildings at True North Crescent, Dartmouth, both of them faithfully net-zero. Another two have since been constructed on the same property, also net-zero.

“That’s when we realized that building good, highly quality, efficient housing is an excellent way to ensure our financial sustainability in the long term,” says Kabalen, “because we’re not going to be on the hook for escalating electricity bills.”

Now they’re bringing affordable, net-zero housing to Yarmouth, specifically to a vacant lot on Shaw Avenue, which the city donated to them in early 2024. The plan is to construct two 12-unit buildings in an L-shaped townhouse configuration. Both will use so little electricity that rooftop solar arrays can, by themselves, produce as much electricity as these buildings consume, feeding excess power onto the grid during high production in summer, and drawing it back out during low production in winter.

Their exceptional efficiency will come from a “passive design,” keeping both buildings naturally cool in summer and warm in winter without defaulting to AC or baseboards.

First and foremost, this entails thick, well-insulated, prefabricated walls, says Kabalen, preventing any unwanted exchange of heat with the outside world. As for intentional exchanges of heat, carefully placed south facing windows will absorb heat from sunlight in winter, while others will create a cooling cross-draft in summer. Rather than manipulating a thermometer to regulate temperatures, tenants will manipulate windows and blinds. Training on these techniques will come with the lease.

“The interesting thing about passive homes is that if you follow the instructions — closing your blinds and windows during the hottest part of the day or opening your blinds and windows to allow a cross breeze during the cooler parts of the day — you’re able to get quite an aggressive temperature differential,” Kabalen says.

Everything about these buildings, from the colour of their sunny and shady walls to the angle of overhangs, will be tailored for passive heating and cooling. And for those inevitable few weeks each year when temperatures are at their most extreme, both buildings will employ a heat pump-enabled heat recovery ventilator (HRV) system, heating or cooling the common area of each unit an extra few degrees when necessary.

Their L-shaped townhouse configuration leaves Shaw Avenue with enough space for a courtyard, inside which they plan to install bike racks, garden boxes, picnic tables, a BBQ, gazebo, trees, and grass, as well as mulched areas for children to play. The final design of this common space hasn’t yet been settled upon, but the idea, says Kabalen, is to foster community among tenants.

“The hope is that we’ll break ground sometime in the next month,” he says.

The build will be stacked with one-, two-, and four-bedroom units, says Kabalen, with one third being very affordable at around $600-$700 a month, one third hovering “near market rent” (about 80 per cent of typical prices for that area), and the final third on the low end of true market value. They hope to have tenants in units by spring 2026.

“Affordable housing needs to exist in communities,” says Kabalen. “The passive, net-zero design is about affordability, and I think the idea that you can’t have both is false. We’re demonstrating to government that higher upfront costs are of value, and result in lower rents to your tenants, if they’re willing to buy in. Net-zero buildings are less costly, both in utilities and to the environment.”

The Climate Story Network is an initiative of Climate Focus, a non-profit organization dedicated to covering stories about community-driven climate solutions.