Clean Energy Heroes: Builder Kostadin Demirov is bringing geothermal to Main Street and Kingston Road property

Beach area builder Kostadin Demirov says its time to get serious about climate change and green energy. His latest project at Main and Kingston will be using a geothermal heating and cooling system. Photos by B.F. Nagy.


“It’s time to get serious,” says Kostadin Demirov, who has spent years building fine custom homes in the eastern Beach area.

His latest move is to act as developer of a 68-unit rental apartment project at Main Street and Kingston Road. And this time he will also retain ownership and become the operating manager of the property. Nineteen of the units will be affordable rentals and the remainder, market rate units.

“I have a daughter and I want to leave something for her,” he says, and explains that she expects him to apply everything he has learned over the years and create a modern residence that befits a great home community and also reflects the times. “The time is right for clean building systems.”

The building will be heated and cooled using a ground source system, the installation of which was the first major work on the site last year.

He says that he is looking at the project’s heating and cooling systems differently than typical developers have in the past. “Geothermal is a long-term investment.”

The technology has been proven in thousands of installations for about 60 years, and is based on the simple principle that below ground temperatures are warmer in the winter than the above ground air, and in summer they’re cooler than the above-ground air.

A ground source heat pump is fuelled by a small amount of electricity, is well known to deliver a high level of indoor air quality and comfort, and costs about 60 per cent less to operate than an equivalent fossil fuel system. It pays for itself quickly and has a long useful life, delivering big savings for decades.

More and more Toronto project developers are choosing geothermal.

In this case a central Mitsubishi heat pump with variable refrigerant flow will condense and intensify pre-warmed geothermal water through a heat exchanger during the winter and do the same with pre-cooled water in the summer.

During the spring and fall the VRF is expected to operate as an air source heat pump.

Each well-insulated apartment is equipped with a Mitsubishi energy recovery ventilator, which provides fresh air, while retaining heating and cooling energy and managing humidity. The HVAC load required 35 geothermal boreholes, each 600 feet deep.

“We will also have solar PV on the roof – 62 panels, 150 square metres, 23 kilowatts,” says Demirov.  “The system should handle all the power needs of the building, including the entire HVAC load of about 100 tons. We may add a battery later.”

He explains that tomorrow’s builders will have to make the numbers and the Toronto Green Standard work, and in that part of the Beach a certain quality level is also a modern-day consideration. Solar and ground source systems fit the bill.

By adding a large solar array Demirov is ensuring that the building will not cost very much to operate, and it will create almost no greenhouse gas emissions.

The Toronto Green Standard is a set of guidelines used by the planning department when approving developments.

For the city it is a tool to move developers gradually into decarbonization.

Evolving voluntary tiers become mandatory every five years.

The expectation is that by 2030 fossil fuels will not be specified in new Toronto construction projects. Demirov is getting ahead of the curve. “As I said, it’s time to get serious.”

B.F. Nagy is a long time Beach resident and author of a new book, The Clean Energy Age. He has interviewed more than 700 experts and written 180 articles on clean energy. The Clean Energy Age is available online, from your favourite bookseller or It contains expert solutions, success stories and top 10 lists of climate actions for homeowners, business managers, government people, and others.

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