The guilt hit Lorrie Rand in her 20th year of designing upscale renovations and sprawling oceanfront homes.

The Halifax architectural designer thought about every concrete foundation, every steel beam, that each of these materials was finite, and she was taking, taking, taking.

“That started to feel icky for me,” said Rand. “I love my job and making houses and beautiful things for people, but I don’t want to be doing bad things for the world because we have very little time.”

Halifax declared a climate emergency in 2019, joining countries and major cities around the world, including more than 500 other jurisdictions in Canada. The capital city of Nova Scotia has since pledged to reach net-zero carbon emissions by 2050. But in order to get close to that ambitious if not lofty target, the city of just under half a million people will need to deal with the single biggest energy waster facing all cities in North America: old, leaky buildings.

“We have this massive cleanup act to do between now and 2050. If we don’t figure it out quickly, how to lower emissions in these buildings, we’re not going to succeed. We’ll never meet them,” said Rand, co-founder of Habit Studio, which specializes in building sustainable houses and low-carbon retrofits.

Halifax, a city of just over 400,000 people, is the eighth oldest in Canada. It is well-loved for its leafy streets and many heritage buildings, which give the city its charm. But heritage runs counter to efficiency.

Buildings and homes, particularly those built before 1996, says Rand, are cities’ worst carbon culprits and make up the majority of structures in the province. And while it remains too expensive for many people and businesses to retrofit their homes and buildings for energy efficiency, this is where Rand comes in.

She and her business partner, Judyann Obersi, and a few like-minded others launched an ambitious not-for-profit side hustle that may be the answer to reducing greenhouse gas emissions in older buildings.