By David Dodge and Scott Rollans
Edmonton engineer Jacob Komar thinks there’s a better way to get to net-zero. As the head of geothermal innovators Revolve Engineering, Komar believes the best solution lies deep beneath our feet.
Conventional wisdom suggests getting to net-zero requires a huge emphasis on insulation, windows and a super tight building envelope. In a 2017 story, Green Energy Futures explained how you could bring a typical home to net-zero for about $95,000. Improve the building envelope, upgrade the mechanical systems, add a solar system, and bingo—even a 1980s-era home can power itself.
Part II in our Geothermal Revival CKUA Radio series,Edmonton builders such as Landmark Homes have been able to build new net-zero homes for $400,000 using the passive approach, but renovations are a different story.
Komar says he has a better, cheaper strategy, especially for renovations.
The solution has already caught the attention of architects, builders and others searching for the most cost-effective path to net-zero and it flies in the face of conventional energy efficiency wisdom which says “make the building as efficient as possible, then add your energy systems.”
“We recently did a little study on this, where we compared what it would take to get a home to net-zero. In a passive approach, the big things are you need triple-paned or quad-paned windows, you need an R50 wall, R80 roof, insulation in the floor, a really good foundation, and really good air tightness. And, of course, you can get that to net-zero using an air-source heat pump, or something like that.”
With a geothermal system, argues Komar, all that insulation becomes less critical and your net-zero renovation costs half as much, about $50,000 in Komar’s case study.
Insulation versus the 400% efficiency of geothermal
“So, we would only replace the windows with triple-pane,” says Komar. “Then, we simply replace the natural gas hot water tank with an electric one, and then we just add GEO. Using the efficiency of GEO, we’d get to almost the exact same energy target but with a fraction of the upgrades needed.”
Compared with a super insulated passive home, Komar’s geothermal strategy gets you to net-zero for half the price. “You’re really only doing three things—windows, electric hot water tank, and GEO. It’s a much simpler approach.”
The reason it works so well is the efficiency of geothermal systems. Ground source heat pumps are in excess of 400 per cent efficient. This compares to 100 per cent efficient resistance electric heating or a 98 per cent efficient furnace or boiler.
Within a threshold, the more geothermal heating you use the more you save in energy inputs. This is why you can spend less on insulation and more on the geothermal system.
Komar’s model makes even more sense on medium-scale projects—such as the social housing project Komar worked on— Canada’s first net-zero church and social housing project.
Geothermal can get medium sized projects to net-zero easily
“We just worked on a social housing project in North Glenora, where we had a church and townhomes on the same site and those buildings shared the same system,” Komar says. “It essentially became a community system.”
The solar-powered project uses a geothermal system to heat a church and 16 adjacent townhomes. There’s no gas hookup and no gas bills. It’s the first project of its kind in Canada.
Part of the magic of geothermal systems is they can either heat buildings, or—running in reverse—cool them. In the case of the Mosaic Centre—an office building Komar worked on—the GEO system often stays in cooling mode even when it’s -10°C outside.
“It’s only 30,000 square feet, but with lots of south-facing glass,” Komar explains. “That only had an R27 wall—it wasn’t crazy. And we found that, actually, if we increased the insulation more than that we would actually increase the energy use.”
Komar has run the model and says geothermal is the most cost-effective way to build a net-zero 50,000-square-foot building. This could have huge implications on mid-sized buildings such as schools.
Shared geothermal multiplies the benefits
Geothermal also works at a neighbourhood scale. Blatchford, Edmonton’s planned net-zero neighbourhood for 30,000 people, will be heated and cooled through a district energy-sharing system based on harvesting geothermal heat.
Ironically, the most affordable path to net-zero may be based on relatively ancient technology. “We’ve been using geothermal or shallow geo energy for thousands of years,” Komar points out. “The Romans used it in their baths. And, in Canada, we have well over one hundred thousand installs.”
Geothermal may have a long history, says Komar, but it also has a virtually unlimited future.
“In a world that is trying to get off of fossil fuels and is energy conscious, we’re going to be chasing efficiency,” Komar says. “In the end, GEO systems are by far the most efficient way to heat and cool a building.”