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Nate the House Whisperer Profile picture
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17 Feb, 5 tweets, 3 min read
Tight well insulated homes perform well, exhibit A:

This 5000 sf new home in Cleveland with an 80kbtu 98% furnace and 4 ton heat pump is only at 67% capacity at 8F. That’s about 53kbtu/18kw output.

A 4 ton heat pump would be appropriate here. For a huge house! ImageImage
As we discuss resilience, air tightness is important. This house clocked a 1025 cfm50 blower door or about 1 ACH50.
Exhibit B: 2300 sf 1950 built ranch. 3 ton heat pump. 2000 cfm50. This heat pump shuts down automatically below 3 F. 5 kw/15,000 btus of backup heat is handling the house at this moment. ImageImageImageImage
Exhibit C: 2200 sf new ranch home, 545 cfm50. 4 ton Bryant 288 heat pump. This also shuts off below 3F and goes to resistance. Medium resistance is 10 kw or about 34,000 BTUs. ImageImageImageImage
As a counterpoint I've seen similar 2500 sf houses running their 80kbtu (and larger!) furnaces flat out in these temps.

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More from @energysmartohio

Nate the House Whisperer Profile picture
19 Feb
THREAD:

Homes as thermal batteries aka resilience.

This house dropped 20 degrees in 8 hours in similar 30-40F temps during the Hurricane Sandy outage in 2012. It took 2 days to recover.

Post project it took 26 hours to drop 10 degrees.

@lloydalter Image
This is a ~2000 sf 1950s Cape Cod in Cleveland Heights.

Full case study on the insulation and air sealing project we did here. It was about $20K and was focused in the attics of this house (it has 4, or was it 5?)

bit.ly/1959CapeCaseSt…
The house started off really leaky at 5800 cfm50 blower door. We got it down to 3100 cfm50. Still not great, but far better. And good enough it turned out.

The house fundamentally changed. The second floor wasn't 10 degrees warmer in summer anymore, it was within 2-3 degrees. ImageImage
Read 16 tweets
Nate the House Whisperer Profile picture
17 Feb
THREAD:

As painful as it is to watch what's going on in Texas, the residential solution basically looks like what we should be doing anyway:

-Tighter, more efficient homes
-Smaller, more efficient HVAC
-Batteries
-More local generation like community solar

Hard to sell tho!
The fact of the matter is we humans don't change until the pain of not changing is greater than the pain of changing.

In residential resiliency creating a comfortable, healthy, and efficient home is a great deal of work. Work that few contractors are good at selling or doing.
The situation in Texas brings up very valid concerns about electrification - how do we handle the really tough cold snaps?
Read 27 tweets
Nate the House Whisperer Profile picture
21 Jan
A Heat Pump Policy Thread:

What if we paid resi HVAC manufacturers ~$400 per AC they manufacture if they make all of their production heat pumps?

Currently US OEMs make ~5M ACs and ~3M heat pumps. What if they were all heat pumps?

This might only cost ~$10 billion over 4 yrs
We think of residential electrification in "Two Clocks".

The first is getting to where 100% of installs involve a heat pump. Doing that by 2030 is REALLY HARD.

The second is running through all inventory, which will take ~20 years.
Every 6 seconds a new piece of residential HVAC starts up in the US.

That opportunity is lost until 2035-2040.

The faster we can move to 100% heat pump installs, the better.
Read 17 tweets
Nate the House Whisperer Profile picture
7 Jan
THREAD:

48% of US residential fossil gas use is from 9 cold (or cold-ish) states. This is a major #electrifyeverything challenge.

Source: eia.gov/dnav/ng/ng_con…

HT @JuliePi31415926

@buildingdecarb heads up Image
I wanted to look at this two ways. First, raw usage by state, then usage per person.

Note that CA and TX are WAAAAYYYY less than the others.

You can tell that PA and MO are a bit mild too.

NJ should be mild (mainly climate zone 4), but isn't, poor buildings?
Note IL in particular. Third highest usage. Chicago is the third largest city in the US.

You literally can't buy a standard heat pump there. Aka unitary, they look like a furnace.

You can in WI just north, but not in IL. No idea why, but it's a fact.
Read 17 tweets
Nate the House Whisperer Profile picture
6 Jan
This is a nice concise look at electrification.

And indeed, quotes are going to be all over the place, and a heat pump should be sized with a blower door and energy use informed energy model.
The heat pump water heater price difference was outrageous!

$4600 is high for the midwest, but I can see it. $7000 is highway robbery. And I seldom give contractors a hard time for pricing.

That's what having fear priced in looks like, or not wanting the job.
Most of California can basically swap a furnace for a heat pump, although the experience with single stage equipment may be mediocre (loud and lots of blowing air.)

Cold climates need to swap very carefully or experiences will suck, which will act like an anchor on demand.
Read 5 tweets
Nate the House Whisperer Profile picture
6 Jan
Gotta give my good buddy Michael Housh of Housh Home Energy a shout out for doing gorgeous duct design work.

This is best practice for new systems, these are ducted mini split heat pumps going into a cool old house that has a boiler.

#hvac2pt0 #thatshowtodoit

@jakedouglas
This is part of integrated project design - have a plan so you can hold everyone accountable. A duct design is not totally sacred, there will be challenges in the real world not reflected here, but it helps guide the project and deliver better results.
This isn't needed on every job, but it should always be available if needed.
Read 6 tweets

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