VS: home heating — heat pumps vs wood (or solar)

There are many in green circles — superinsulated/zero energy home/passivhaus circles — who think that heating with electricity (ideally with an air-source heat pump) is the ideal way to heat a house with solar electric (PV) panels on the roof (well, or yard). Example link

As someone with a house that is exactly that, let me chime in.

Heat pumps: PROS
1. No hole needed in house for exhaust or air intake
2. No air-quality or safety concerns since no burning of wood or fossil fuels in the house
3. Math is easy if you are trying to be net-zero. If everything is electricity, then there is no complicated math to do converting gallons of propane or cords of wood burned into KWh. (not much of a reason)
4. Now you have AC too. OK, so you saved a few bucks. Window ACs are only $80 though. And you house probably doesn’t need much more than one of those. Really.
5. No baseboards taking up space. But there are other approaches (forced hot air and such) to deal with that.
6. Quiet inside. Wow, very very very quiet. No furnace, furnace fan, or boiler making a racket. (Aside: And no humidifiers in winter… thanks to the tight superinsulated house part…)
7. Electricity tends to be price-stable vs the price of propane and heating oil which seems to whip-around a lot.
8. Usually a bit cheaper to install vs a “central” system esp in a very small house. But add in the price of the HRV or ERV stuff if you have that too.
9. Point source: I list “point source” below as a con too. Some like point source heat since it allows zoning, getting cozy by the “fire” and such. Flip side to everything.
10. Future safe. Electricity can come from many primary sources.

Heat pumps: CONS:
1. Can be a bit loud outside (well not LOUD, but there is a fan running, like for central air-conditioning, all winter) So if you are noise sensitive maybe there is a quieter heating approach? Not sure what qualifies as the quietest. Radiant floor heat?
2. PVs should not be thought of as anything more than an offset in my opinion. Don’t think of that electricity your panels made as yours. Who cares WHO uses it. The point is to reduce CO2/greenhouse gases overall. In other words, if you make electricity, dump it into the grid for your neighbor to use, and burn some wood to keep warm instead, then you are ahead (in my eyes) of someone using that electricity directly to heat their house with a heat pump.
3. In very cold areas, you will need either a HYPERHEAT model that keeps up with sub-0F temps, or some back up (maybe electric space heaters). Most other air-source heat pumps drop their output by a lot when it is VERY cold.
4. Power outages. You will have no heat. Now, that might not matter as much, because your superinsulated house has a certain amount of “passive survivability” built into it with all that insulation, but if we are talking comfort here, then grab a wood stove or a propane heater needing no electricity to run. There are a few!
5. “Non-traditional” Looks: Some might think they are ugly. I don’t mind them. Just different. And controls. Our Mr Slim one has a “remote” vs a traditional thermostat. And the model we got doesn’t control all 4 internal heads. So like a house with zoning, you have to walk around and set each individually.
6. Point source: We have 4 of these inside “heads”. One on a wall on each floor (basement, 1st, 2nd, 3rd (attic)) But there is not heat/coolth pumping into every last room. Doesn’t matter much, but bedrooms are a little cooler — 5F? Coldham/Rocky Hill study seems to say. Ask google.

Wood: PROS
1. Local
2. Carbon neutral
3. Ambience
4. Simple technology (especially if not pellets and not catalytic)
5. No electricity needed (heat when power outages)

Wood Stoves: CONS
1. Lugging stuff
2. Might be difficult to vent properly in a very tight house. Indoor Air Quality risk. Especially with a pellet stove which loses electricity.
3. Even the smallest pellet stoves will overheat some houses that are superinsulated. But big whoop. Run it on thermostat-mode. And open the window if you must!
4. Particulate pollution. You might live pretty near other people or in a town or city that prohibits wood burning.
5. Related… Gotta know what you are doing. (slow-burning, smoldering wood stove fires pollute like crazy and smell up the neighborhood.)

Solar Thermal Heating: MIGHT BEAT WOOD IF…
1. You have sun
2. You have a spot to put the solar thermal panels and a HUGE 1000 gallon tank in your basement
3. You have already done energy efficiency fixes — insulation, CFLs, etc. (see builditsolar.com)
4. CON: Up front cost is going to be higher than the wood (at least a pellet stove vented out the side of a house) unless you are a DIY person (see builditsolar.com)

Prius: PROS (W/holistically speaking, maybe this is a better place to start…)
1. Do the calculations in KWh. If you cut the number of gallons of gas you use in half by driving a hybrid or electric car, how much is that in KWh?
2. Energy Independence: coal and nukes (for making electricity) are “local” to the US, vs gasoline comes mostly from other countries. Propane is 90% from US. Natural Gas is ???
3. Use as a backup generator for house

So what would I do?
Well right now we use an air-source heat pump to heat our almost passivhaus ZEH. But I hope to do more solar-thermal heating in the future. 5 days of storage would get you to 97% solar “if cloudy days are like coin flips”. And the no-electricity propane heater is intriguing, especially for a little backup. Check back in a year!

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