Should I heat my home with a pile of bricks?

Given how cheap electricity is at night, this might actually make sense.

That box on the wall is full of bricks

In Ontario, where I live, Premier Doug Ford and the Conservative government are spending a quarter of a billion dollars to expand access to natural gas, and are fighting a recent decision by the regulator, the Ontario Energy Board, that would have made developers pay for gas infrastructure upfront rather than have the customers pay over 40 years, by which time it might well be a stranded asset. This is the same government that spent millions to cancel renewable energy contracts and now has to build new gas-powered “peaker” plants to fill the gap between peak demand and the base supply from nuclear and hydro.

Meanwhile, those nukes and dams produce so much electricity at off-peak times that the utility sometimes pays American utilities to take our excess juice at night, and regularly sells it for less than cost. They have introduced Ultra-Low Overnight rates where they are almost giving electricity away at 2.8 cents per kWh to encourage us to use electricity at night. Other utilities are doing this as well; in New York City, the off-peak rate is 2.33 Lincoln pennies.

I have been looking at ways to replace my combo gas boiler that supplies our radiators and water heater in our 100 year old house, and have been thinking about a heat pump. They are not perfect; they can be noisy, and they leak refrigerants that are serious greenhouse gases in North America, where low-impact refrigerants are not yet available. I wondered if there is a better way that takes advantage of the incredibly cheap overnight electricity.

Surely, there must be ways of storing that cheap electricity at night and using it in the daytime. Batteries for storing electricity are way too expensive, but all of our natural gas is used to generate heat, and it can be stored.

I recently discovered these Ecombi “smart storage heaters;” they basically have electric heating elements and a pile of bricks inside. Sophisticated controls fire up the heaters at night when the electricity is cheap, and mete out the heat all day with fans as required.

It literally is a pile of bricks; the installer puts them in.

It turns out that a little thermal mass can store a lot of heat! I spent a few hours yesterday doing the math, sizing a storage rad for every room in our house, looking at my gas consumption for the coldest month last year when I paid $416.24 for 697 cubic meters of gas, which converts to 7,346 kWh. At the low overnight rate, my electricity for heating would have been $205.69.

But I didn’t have to spend the day doing math, because Enbridge kindly included this chart of different energy sources for a typical house in their application to expand gas into an Ontario town. Gas prices were way up in early 2023 because of the war in Ukraine and the boom in Liquid Natural Gas (LNG) exports, so that you have to wonder why Doug Ford and the conservatives are pushing it so hard now, when conventional electric heat from baseboard radiators costs only 2% more than natural gas. But if I plug in storage heaters and use the night rate, the heating and hot water bill is for the year is $549, a quarter of the cost of gas.

I suspect that spouse Kelly is not eager to have me rip out all our radiators and related plumbing, but there are alternatives that are more sophisticated than a pile of bricks; a few years ago I looked at Sunamp Heat Batteries that were full of phase-changing materials. I liked their approach to the problem:

"Sunamp set out to explore the potential of using thermal energy storage to make buildings more energy efficient, sustainable and self-sufficient, whilst reducing carbon emissions by optimising renewable energy sources on-site, supporting the grid to allow on more renewable electricity sources and harvesting waste heat for re-use."

heat pump on the left/ time of use optimized on the right

At the time, gas was cheap at 3.1 cents per kWh and electricity was expensive at 8.5 cents per kWh off-peak. The math didn’t work unless I connected the heat battery to a heat pump, all of which gets more expensive and complicated. Today, it is a very different story; the Sunamp unit would make economic sense on its own.

Of course, there is no guarantee that prices will stay like this. When electric cars become more common, everyone will be filling them at night with cheap electrons, they will sop up a lot of the excess and I doubt they will still cost 2.8 cents per kWh. Also, according to my latest gas bill, prices have dropped, so the savings might not continue to be so dramatic.

If Doug Ford was smart (he isn’t), instead of subsidizing every new customer with $26,000 of gas infrastructure, he might put the money into insulation and windows, build all these new houses to the Passivhaus standard and retrofit the old ones. Then everyone could stay warm and toasty with nothing more than a pile of bricks.