Th3 Core

The fuel-switching issue is interesting. And the fact that they have units that work down to zero F. We're on the cusp of being able to use them for heat. Since it is not uncommon to go into the teens at night and rarely below 25 during the main part of the day, some people do get by with just the air-source heat pump, but when it's in the 20s, they run and run. The overall efficiency of the house is a big factor. The neighbor with a new SIP house has no trouble. The neighbor with an old house with very little insulation has it run non-stop for weeks at a time, sometimes with huge amounts of ice building up on it.

I've also been curious carbon and cost tradeoffs. I think the cost tradeoff would be less here because electricity is expensive in CA, though with the pricing going into effect this year, there will be summer and winter rates for us and the winter rates are a lot lower.

Tiered rates are a big disincentive. If changing to electric heat pushes me into a higher tier, it means those KWH are all at the most expensive rate. If I go into Tier 3, that's 41 cents per KWH. My lowest possible rate in the winter is 23 cents. Google says the average rate in MN is 11.5 cents. So if I went to electric heat, I would be almost 2X to 4X that, which cuts into the savings from a heat pump.

Insulate, insulate, insulate!

Exactly.  This will serve anyone well, long into the future.

But, having been in the real estate development business, it's amazing to me how many home buyers pay so little attention to this.  They want play area for their drooling spawn, home theatre room, snarfy kitchen, bathrooms big enough for bus loads of people and a three car garage but if you tell them the house is built to be "green" you get a Homer Simpson blank look.

Tear down

In the UK the building regs don't always make a place better.  Our place in Wales, in a windy (very windy) spot on the coast, has an extension. It has thick insulation in the roof and the walls and actually the floor.  The problem is that the vent requirements mean that the wind that travels through the insulated cavity cool the wall down so much that the 1960s (or 1950s?) wall next to it is warmer.

Also, the venting in the windows means that on a windy day.... it's cold.


I am appalled.

>UK

There is a similar scheme already running in Scotland, first come first served until the money runs out. Up to £10K interest free loan, and up to £7500 'cashback' when installing a heat pump. Cashback effectively being a grant. Subject to credit checks of course, and mandatory that your energy performance cert for the house doesn't recommend loft or cavity wall insulation.

Think the newly announced grant equates to about 50,000 installations so not a huge amount considering there's 20M households in the UK- but decent incentive for those who want to get on with it.

When you factor in RHI https://www.gov.uk/renewable-heat-incentive-calculator you can potentially make the money back within a few years.

>stone wallS?  R-value SUCKS.

For sure. At mine they're cold to the touch over the Winter months. Suspended floor also needs a look at as floor is also cold. Not any easier that older houses have to be 'in keeping' with the rest of the street so a new external facade tends to not be an option. Regulations...

Looked at internal wall insulation via the same routes as heat pumps (Home Energy Scotland). £10K loan available, £4K back. Quote arrived at £12K and that's not for the whole house, maybe 60% of it. Company that quoted me flat out said they ignore kitchens and bathrooms, too much hassle for them apparently. Doesn't take into account cornices or alcoves or generally any alteration near the outside corner walls. The local council run a means tested scheme where they will grant £7500 and that loan stuff can come afterwards. All seems like a gift but there's obviously some work required after it wrt the original look.

If UK gas prices stay where they're at may all end up the better economical choice.

Tempted by the idea of a GSHP but got a new gas boiler after moving in here a year ago. Seems like insulating is the priority.

Long ago, I read that it takes about 6 meters of stone to equal 3.5 inches ^{9 cm} of fiberglass insulation.  AFAIK, there is currently no 'reasonable' interior sheeting material tech that will work adequately without one helluva lot of work (and some interior loss of space).  Air-to-air heat pump output is cool-ish and slow to bring the room up to temp.  It'll need to run much longer than your boilers.   ...And we haven't even discussed old windows.

I foresee a great deal of wailing & chattering of teeth in uninsulated legacy construction.


> if you have a big window

Yeah, my house is 20-25% glass.

That resulted in condensation which froze into huge ice blocks which is how I noticed it was running non-stop. At a certain point the ice touches the fan blades and I can hear it running 24/7 from 100m away.

The new one probably has a defrost cycle.  Its raw heat to defrost, so is pretty inefficient.  They work best where the water does not freeze.  I cannot imagine why you would have one somewhere that cold, I suppose the rest of the time its cheaper to run than straight elec heating, but the cost of installation must be hard to recoup.