Heya! I've been lurking for a while on the various formats that came together for the HEP Forum. Haven't posted/contributed for a while due to crazy busy schedule (that's good, right!?!)

I'm working on a series of blog articles on Exterior Insulation & Deep Energy Retrofits, specifically in cold climates.

Just to give you some background, I've worked with clients to design and carry out DERs, specified some others, and am now working on a demonstration project for NZE renovations, and I sit on two technical working groups in Canada focussed on retrofits, NZE and exterior insulation optimization.

The articles will start with the projects that I'm involved with, but I want to broaden the scope by getting more information out there on who's doing what, how cost-effective different approaches are, if costs and approaches vary regionally, and how do we improve performance and cost effectiveness. In addition, there will be articles on tackling the actual details: roof overhangs, connection to existing house, door/window openings, moisture management, etc.

If you have worked, or are working, on Deep Energy Retrofits with exterior insulation, please give me a shout so we can set up an interview time. Or you can drop a line here.

If you've got any questions or concerns you want to see addressed in the blog articles, jump into the discussion here.

I'll post the articles in HEP Forum as I publish them.


ps you can find me at Bfreehomes and Blue House Energy

Tags: DERs, NZE, climate, cold, deep, energy, exterior, insulation, retrofits

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Shawna,  I agree with Nate and Ted, as far as ROI is concerned it's hard to beat top, bottom, infiltration and then electrification. When you carefully look at heat loss, spending a lot of money on walls has a very limited gain for the cost.

  That all being said, I find many customers are making decisions based on philosophical inclinations. We have a tendency to assume all decisions are based on an ROI when reality can be much different.

  Electrification  (heat pump) typically tips the equation positive especially with oil and propane.

Hiram College TREE House


15,700 kWh actual usage, 2000 sf, 36,400 BTU/hr load calc, 962 cfm50 final blower door. Runs lots of resistance for basement floor heat. 6670 kWh heat pumps, 2130 hot water (mostly floor heat),

8800 kWh heating and cooling.

3" polyiso on walls, dense packed walls. insulated foundation, R-70 attic. 2.5 ton Lennox multi split heat pump. 

Habitat for Humanity Retrofit


13,000 kWh/year 700 square feet, 700 cfm50 blower door, 8,000 BTU load calc

2" exo XPS on walls, 1" closed cell interior, 3.5" closed cell on roof deck. 2 ton 2 stage Goodman 16 SEER heat pump.

Jonathan Nigro


11,000 kWh/year, 1730 square feet, 1860 cfm50 blower door, 54,000 BTU/hour load calc.

5800 kWh/year heating & cooling.

Dense packed walls, foamed rim joists, foamed roof deck in walk up attic. Carrier GreenSpeed 3 ton heat pump. Not an exotic retrofit.

Paul S.


Dense packed walls, air sealed flat attic with R-60 cellulose, 2" closed cell on basement walls for moisture control. 2 ton Carrier GreenSpeed heat pump.

15,000 kWh/year, 1300 sf, 1820 cfm50 blower door, 26,925 BTU/hr load calc.

4800 kWh/yr heating and cooling.

There are a lot of different factors in here, but the usage for heating and cooling on the first two, which have exo insulation, are disappointing considering the cost and level of effort expended. Putting the extra money into better air sealing, a really good heat pump and PV is often a better use of funds if energy costs are close to national averages.

We're selling projects pushing a $30K average in a market with low housing values, moderate incomes, low to moderate utility costs, and no programs.

This is truly market based Home Performance, which is what's needed moving forward. I'm just not sure how to sell exo insulation and double/triple job costs when the results we've seen are thoroughly "meh". I'd LOVE to be proven wrong, but the odds seem pretty low since we're already unicorns. Is a focus on exo just slowing us down?

Oh, a question to ask from a climate change standpoint is would you rather budget money be put into exo-insulation/deeper retrofit or into electrifying the HVAC. Electrification drops site usage by 40-60% in our experience. If renewable generation is used, that's close to a real number because you only have to account for line losses in the 3-10% range. I'd love to see what your work comes up with!

Climate change:

Here in NS, we have +1kg CO-e/kW generated, ±60% of our electricity comes from oil and coal. With the line losses, it turns a heat pump with a COP of 2 into the equivalent of a 80% efficient oil boiler, and the site-based oil boiler produces less CO-e/kW-e than our generation mix.

We pay high electricity prices, and we have some of the oldest housing stock in North America, which is in desperate need of ***exactly zero*** more low-hanging fruit energy upgrades, and serious DER measures. Also, the cost of PV is still higher here than pretty much anywhere else, given our small market and hefty shipping prices.

Electrification (which really means use a heat pump?) to help reduce greenhouse gas emissions is still the long-game here in NS, unless you go for high-performance cold climate units that are properly sized.

Which is not what's happening.

What's happening  is lots of squinty-eyeball sizing for lower performance mini splits. We don't have many forced air systems, typical older stock home will have electric strip or oil boiler delivery to convectors.

Having fought against the central-Canada/Southern Ontario bias against the value of energy efficient envelope renovations in favour of high performance mechanical options of any sort for a few decades now, I'm a bit tetchy on the subject...

It's important to the discussion that blanket statements about one approach or another need to be framed in context of the climate zone and generation mix that you're working in.

Aha, I didn't realize this was for your province primarily. Fuel rates do move things around a lot. I'd love to see a few energy models from up there!

PS Don't worry, I'll keep making blanket statements... =P If nothing else to keep your blood flowing, sounds like you need it... 

I'll be working on a contract to do a study for Atlantic Canada shortly. The ask is not just about my region, tho. It's about what works/doesn't work, has/hasn't work. Finding out what the stumbling blocks are, finding out what the obstacles are.

For example, 4-5 years ago, flashing those 'innie' windows was a pain. That's likely changed, with better products. So that was a stumbling block.

You're in a region with cheap gas. That's an obstacle, because the ROI will always tank.

BTW, I've got a shit-ton of modelling on this stuff. Did the first 'Approaching Net Zero in Existing Houses' study in 2004 or 2005. Have over 2500 runs: 7 house types in 6 cold climate regions.

All of it is on an archive 1TB disk that has been in friggin disk hospital for extractive surgery of my precious data for over a month. I'm told there will be complete recovery of data but they're looking for a 'donor' disk that can run the platters. FML. And major note to self: archive shit in more than one place.

Keep making those blanket statements, I'll practice my verbal skeet shooting skills on ya!

I have a bunch of questions:

1. Do you have modeled vs. actual use on many projects?

2. How do you sell these projects? How many buy them?

3. Are contractors good enough to do these at a high enough quality to avoid issues like air flowing behind the exo insulation?

4. Are there better places to spend the (rather substantial) money for an exo retrofit?

We have two exo projects, actually. The second one was the Habitat project. Usage on that one is disappointing as well, but part of that is HVAC related. I don't think the exo insulation was super well executed, though, and that was someone who cared.

While modeled load matched reality on the Habitat project, usually we see the load be less than modeled when we check with Ecobees or Carrier Infinity performance curves. That's two projects that tell me reality isn't as good as modeled. These projects don't grow on trees, so it's enough to inform my intuition to heavily question DERs.

Well, those are the questions I'm asking people who are doing the work.

It's because I don't have a decent set of data points for questions 1 through 4 that I pushed this ask out there.


My company, ISEEB (Institute for Super Energy Efficient Building), is set up to train constructors in all of the principle and techniques to do deep energy retrofits.  Check out   http://iseeb.us  >>.  I would very much like to make contact with you and see how much we can collaborate with each other.

I also believe that exterior retrofits are the only economical way to do DERs.

Thomas A. Peterson

Cell:  (207) 310-0030

E-mail:  tivasamoht@aol.com

Thanks, Thomas! Will be in touch.

I don't know if you've heard from Jon on this, but I was at Snug Planet when it was involved in a NYSERDA study on DERs.  A few contractors, around the state, doing different treatments.  One did exterior spray foam, Snug did a single layer of thick exterior polyiso, can't remember the others, and I can't find the documents/reports on NYSERDA's site.  The PM at NYSERDA was Greg Pedrick if you want to reach out to him.

I agree with Gary about the cladding replacement.  If that's already in the cards, then an outsulation package "makes sense" and that comes with all the usual caveats about paybacks.  I'd add that now, with all the goos we have available, flashing existing windows would be MUCH easier.  We did this project...4 years ago?  5?

You know how to get in touch if you want to chat.

I know that NYSERDA project fairly well!

I spent a week or so w/Greg P after the project was completed, as part of a research study we were doing for our 'REBlock' DER program pilot.

I think we're into 3rd gen details now to improve efficiency and efficacy of outboard insul projects.


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