7th June 2022

As part of getting my literal house in order I’ve wanted to de-fossil fuel our house. When we moved in a couple years ago, our electrification vs. fossil fuel status was pretty common for our area:

Not so great, percentage-wise! I didn’t really know what to do about space heating, so I settled for applying to my gas supplier for “renewable” natural gas. That felt better than doing nothing at all, and it approximately doubles our monthly bill so there’s some incentive towards conservation. But paying to keep natural gas pipes full never really felt like the best outcome, even if we were helping fill them with captured waste methane rather than newly extracted natural gas.

Later, I got (very) side-tracked trying to figure out how to get photovoltaic solar panels installed on our place (uncommon shingle type, questionable electrical choices made by home builder, …). For now, I’m putting that off:

  1. BC Hydro is currently producing 98% of its electricity from clean sources. And while there are certainly environmental concerns stemming from huge dams, transmission lines, land use, etc., I’m probably not going to do better on CO₂e with rooftop solar.
  2. It rains here in the winter. A lot. So our expected solar yield isn’t as enticing as California and similar.

However! I’m happy to say that I’ve gotten back on target and now have the permits and electrical work done for both an electric heat pump and an electric water heater.

After plenty of research, I satisfied myself that we didn’t need to move to forced air and add ducting, and could stick with in-floor water heating. Given that, we chose this air-to-water heat pump. It also advertises the ability to do some amount of cooling via in-floor hydronic. I’m not optimistic that it will be very effective because it obviously won’t control humidity, but even a few degrees off the peak temperatures of the next “heat dome” would be welcome. (Most homes in our area don’t have A/C because as recently as a few years ago it seemed unnecessary.)

The heat pump is backordered for some weeks, but has been ordered, and should be installed before the next heating season. My very rough back-of-the-envelope calculation based on:

  1. last winter’s natural gas consumption
  2. estimated efficiency of current boiler
  3. conservative estimated efficiency of the heat pump (allegedly COP=3.1, but I’m assuming closer to 2.0 in real life)
  4. our local hydro kWh price (assuming all Step 2 due to EV charging at home)

suggests that it’ll be slightly cheaper to run the heat pump than the gas boiler, but only because we’re opted-in to 100% RNG. Otherwise, it’d be roughly a 1.75x factor for electric. But there’s a lot of fudge in those numbers, so for now I’m just looking forward (?) to the sting of a low-CO₂e Hydro bill, and we’ll see what the data says in a year.

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