BURSZTYN: The heat is on to reduce carbon emissions

If we want to reduce CO2 emissions, we must gradually switch our heating systems from natural gas and oil to electricity.

Quebec already heats most houses and commercial buildings with electricity. However, Quebec has done this cheaply and tends to use electric baseboard heaters. That made sense for them because their (water) electricity is particularly cheap.

It would be costly for Ontario to follow suit. In order for Ontario to heat electrically, we need to install heat pumps.

Heat pumps are not mysterious. They have been in use for almost 150 years. We all have at least one in our homes. Our refrigerator is a heat pump because it extracts heat from the inside and releases it to the outside.

A liquid is vaporized in tubes inside the refrigerator. Evaporation cools those tubes—just like evaporating sweat cools us when we work hard in the summer. The refrigerator vapor is then compressed by a pump, forcing it to condense back into liquid. Condensation heats the “condenser coils” – behind or below the refrigerator – which cool by releasing heat into the room air. The liquid evaporates again, repeating the cycle.

A domestic heat pump works in the same way. The hot condenser is inside the house. A fan blows room air over it to heat the house. The evaporator coils are outside, so in order to extract heat from the cold winter air, these coils must be colder than the daytime temperature.

And this is the problem. The colder the outside temperature, the harder a heat pump has to work to generate heat for your house. In other words: the efficiency of a heat pump falls as the ambient temperature falls.

Heat pumps are a clear winner in the southern United States and much of Europe, where winter temperatures rarely drop below freezing. In southern England I only experienced minus 10 degrees Celsius once in 15 years and minus 5 degrees Celsius for less than a dozen days!

In contrast, my gas heater works just as efficiently on a cold February day — 96 percent of the fuel energy goes into heating my home — as it does during the spring or fall. A stove is independent of the climate.

A heat pump has two advantages over an oven. First, it can be operated in reverse to cool a home in the summer. An oven cannot do that.

Another advantage is that a heat pump provides more heat per unit of energy than a stove, by “moving” heat from one place to another. A typical heat pump has a Coefficient of Performance (CoP – a measure of efficiency) of three; it supplies three units of heat for the consumption of one unit of electrical energy.

The claimed or advertised CoP is a seasonal average. In spring or autumn it can reach a value of five. In the dead of winter, when it’s minus 20 degrees Celsius outside, the same heat pump can work as an electric skirting board heater with a CoP of one.

The decision to replace a stove with a heat pump is based on three factors. First is the installation cost. Heat pumps are more expensive than stoves. Second is the price of energy. Electricity is usually more expensive per energy unit than natural gas. However, because the heat pump provides more heat per unit of energy, it may be cheaper to run in some jurisdictions.

After all, burning fossil fuels always produces carbon dioxide. When the electricity in your jurisdiction is wind, solar, hydro, geothermal, or nuclear, little or no carbon is released.

Ontario’s electricity is 95 percent carbon-free, which should make heat pumps a winner when it comes to carbon emissions.

Unfortunately, our nuclear reactors, which provide 60 percent of Ontario’s electricity, are beginning to fail this year as they exceed their sell-by dates. It is also unfortunate that the Ontario government plans to use gas turbines to generate electricity.

These have an efficiency of around 45 percent. Some of the electrical energy is lost to heating wires and transformers, giving you only 40 percent of the fuel energy. Despite this, heat pumps are a winner when it comes to CO2 emissions.

The efficiency of heat pumps can be increased by exchanging heat with the earth instead of air. At a depth of two meters, the bottom temperature is fairly constant at 15 C, winter and summer. Instead of exchanging heat with air, which changes in temperature by 50 C seasonally, you can bury pipe coils in the ground.

Of course, excavating for a geothermal heat pump is far more expensive than installing an air source. More importantly, few urban dwellings have enough land to house a geothermal heat exchanger.

The heat exchanger could be installed by drilling into the water table. The city of Barrie used to ban this. City officials were – justifiably – concerned that heat exchanger fluid could leak and contaminate groundwater. Also, they didn’t want such installations to raise the temperature of Barrie’s aquifer.

The operating costs remain. Burning gas directly in your home is definitely cheaper than burning it in a power plant to heat your home electrically.

However, there is another excellent way to reduce CO2 emissions. Insulation!

Insulation comes in a variety of forms. The cheapest and first step is to put insulation over the ceiling. This is simple and highly effective, winter and summer alike. Basements are often not insulated, resulting in heat loss to the floor through the walls and floor. Wall insulation above ground is expensive, since the outer cladding of the house is removed, additionally insulated and then a suitable, weather-resistant facade is attached.

After all, in our climate, windows should be triple-glazed. This often doesn’t make economic sense unless you need to replace them for other reasons. Then opting for triple glazing is only slightly more expensive than double glazing.

No matter how you want to heat your home, insulation is always a sensible first step.

It is also worth noting that several European countries have banned gas heating in all new homes from a later date. They must have heat pumps.

For more information, as well as pictures and diagrams, see this University of Calgary article.

Barrie resident Peter Bursztyn is a self-proclaimed “recovery scientist” who has a passion for all things science and the environment. The former retired university lecturer has taught and researched at universities in Africa, Great Britain and Canada. As a member of BarrieToday’s Community Advisory Board, he also writes a semi-annual column. If you have a question Peter might be able to answer or something you’re curious about, email us at [email protected].