The hero of the renewable
energy revolution is hiding
in your basement.
Let's get right to it. We're talking about HVAC. And yes, we know it's hard to imagine a less sexy image. Bear with us a minute and we'll explain how the combination of trusted technologies and a new service model nets out at a less expensive, easy way to supply our heating and cooling needs while doing our part to transition to renewable energy.
Get excited
about heat pumps.
If you can wrap your head around how a refrigerator works, you're halfway there.
Basically, a heat pump moves heat--it doesn’t generate it. It can act like an air conditioner to remove heat from your home or in reverse to heat it.
Since heat is just being moved, heat pumps are very energy efficient, usually 3-4 times as efficient as a typical furnace or air conditioner. Heat pumps run on electricity, and if the electricity is low carbon, like it is in Ontario, have almost no carbon footprint.
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District Geo-Exchange
You use heat energy for lots of things: to heat your dinner, warm your bath water or remove it to make popsicles. Each of those uses are treated as unrelated activities. But imagine being able to reuse the heat energy. For example, the heat you take out of your house in summer could be used to warm your pool.
Now apply the same approach to parts of a neighbourhood instead of parts of your house. Instead of heating and cooling each building from scratch as needed, energy could be shared between buildings with off-setting needs. Heat removed from water to make ice for skating rinks could be used to warm neighbouring houses.
Traditional District Energy
Typical district energy systems produce heat (high-temperature hot water or steam) or cool (chilled water) at a central plant. Then the energy is distributed through separate hot and cold underground pipes to connected buildings in a loop.
Individual buildings don't need to generate their own heat or cool and so can avoid boilers, chillers or cooling towers. In the case of heating, each connected building removes heat energy for space heating and hot water, returning cooler water to the pipe and, eventually back to the central plant to be heated again.
There needs to be enough heat in the pipes to meet the needs of the last connected building on the loop. So central plants need pipes large enough to distribute the heat for all the buildings. Large pipes are expensive to install, so this approach works best in high-density urban areas with large buildings.
A central plant burning natural gas is more energy efficient than gas-fired boilers for each building, but a 25-30% reduction in energy for a few buildings doesn’t help municipalities meet their decarbonization goals for the city.
Standalone Geo-Exchange
There are two basic parts to geo-exchange: a heat pump and the source of heat—a loop of pipe underground filled with fluid to exchange heat energy with the earth.
Laying underground piping is costly. Geo-exchange is more practical in rural settings where there's plenty of room to dig trenches to lay pipe in and competing energy sources like trucked in propane/heating oil or electricity are more expensive.
Urban areas are less practical because of the range of variables that need to be accommodated when laying underground piping in a densely populated, multi-use area with existing infrastructure. Roll in the likely availability of natural gas and the cost savings from the more energy efficient heat pump is not enough to offset the high capital cost of drilling.
In many cases, it can take 20+ years to earn a return on standalone geo-exchange.
District Geo-Exchange
Thinking in districts creates efficiencies, economies, and a few new opportunities that isolated buildings can’t touch. A utility operating a shared geo-exchange system can:
Nimble Municipalities
Leading Business Owners
Smart Home Owners