Green House Fest (greenhousefest.org) is almost here — 27 homes, 59 different installations, 10 different features including electric cars, induction stoves, induction cooking parties, on-demand water heaters, solar panels, heat pumps, energy monitoring, and on-demand water heating.
We started the planning for this tour with the heating question — how do heat pumps work, can we change our homes to electric heating using heat pumps, and what experiences can families who live in homes with heat pumps share with us?
The project grew from only heat pumps to include electric cars, solar panels, insulation, induction stoves, and cooking parties. Nonetheless, the underlying goal has stayed the same — how do we decrease and eventually stop using fossil fuels in our own homes? Heat pumps exchange heat in the air between outside and inside, heating your home in the winter and cooling it in the summer. Depending on your home's design and insulation, you can heat your home with a heat pump. And yes — heat pumps are an essential part for getting out of the fossil fuel problem.
As we've planned and marketed our Green House Fest to home owners, the question we hear most often is how you should use electricity to heat water. Most homes have switched from gas-fueled tanked water heaters to on-demand systems, which reduce the total amount of gas used. However, it still leaves you reliant on a fossil fuel, not to mention it supports the development of more pipelines and more drilling for fracked gas. We have also learned that natural gas is as much a contributor to green house gas emissions as coal is. That is because of the methane leaks from the wells where it's drilled all the way to your house. See Bill McKibben's excellent article on the matter.
What's a well-meaning home owner to do? Is there even such a thing as electric water heat? If yes, can it be efficient? The answer to both questions is yes — heat pump water heaters, which work much like their home heating brethren, will heat up your water using your home's heat and electricity — no gas required. One home on our tour, 16 Cleveland Road, has such a heat pump hot water system and the project manager from the Design/Build Byggmeister will be there on Sunday to show you how. Full Green House Fest Map.
Rachel White's take on heat pumps:
Electric Heat Pump Water Heaters
By Rachel White, Byggmeister Design/Build
When we transition a home to all-electric appliances, our first choice for a water heater is most often (although not always) a heat pump water heater. Heat pump water heaters are roughly twice as efficient as electric resistance hot water heaters. They are also much more practical for whole house applications than tankless electric hot water heaters. A tankless water heater sized to meet the needs of a whole house would draw huge amounts of current and would likely require major electrical upgrades.
Heat pump water heaters do have some limitations though, which means that they aren’t the best choice for every situation. In order to perform optimally, they need to be installed in a fairly large space that stays relatively warm year round. In addition, heat pump water heaters are somewhat noisy, and they cool the air of the space they are installed in.
If you have a basement that stays above 50 degrees most of the year and you aren’t concerned about noise or comfort impacts on adjacent living spaces, then a heat pump water heater could be a great choice when you're ready to replace your gas water heater.