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Deep energy retrofit experiences

david_bash | Posted in General Questions on

Hi Everyone,

My family is relocating back to Massachusetts from the Midwest and we’re there for the long haul, so we’re going to buy our first home. I’d always planned on building, but after looking at the cost of land in the towns we’re interested in and talking with high-quality green contractors and the green prefab companies in New England, it turns out my cost expectations were unrealistic. A new, well-built green home around 2,500 square feet (plus the cost of land) ends up somewhere in the neighborhood of a million dollars, and I don’t feel comfortable spending that.

A note – I know you can do it for cheaper, but my wife and I are professionals with children and we work full-time and have no experience or interest in construction, so doing the work ourselves is off the table. Additionally, we’re not going to build a swimming pool or buy a $10,000 Wolf Range or Subzero freezer, but we’ve looked at trim and design options and it all quickly adds up.

Instead, I’ve been reading more about DERs, and while they don’t always make immediate financial sense, they seem like a way to help my family get to a house we’ll be happy with. There are many houses where we’re looking that run ~$500K, so dropping another 150K for new windows, siding insulation, roof, and HVAC to get a comfortable, healthy house seems like an attractive option.

Does anyone here have direct experience in performing a DER, in New England or elsewhere? Any insight you can offer would be greatly appreciated. Thank you!

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  1. GBA Editor
    Martin Holladay | | #1

    Have you visited the "Category" page that indexes all of our deep energy retrofit articles? Here is the link: GBA Category page for Deep Energy Retrofits.

  2. Expert Member
    Dana Dorsett | | #2

    Pricing varies quite a bit in MA, but Carter Scott/Transformations builds some remarkably affordable Net Zero Energy homes in central MA.

  3. david_bash | | #3

    Martin - I had been using a general search and didn't realize there was a specific category - thank you for the link!

    I've read your article before about the lack of ROI on most DERs. I think where I have some confusion is around comfort. I believe that solar panels can greatly lower your energy costs, and I'm definitely in favor of that. Everyone should be a fan of lower ongoing energy costs with a quick ROI on the investment. However, will solar panels and ASHPs alone make an older, poorly designed home comfortable to live in? Every house I've ever lived in has had comfort problems - some hot rooms and some cold ones, condensation on window interiors in the winter, they're either really dry or face moisture problems in basements...I'm trying to avoid that now, and it's hard to see an affordable way to do that where I'm looking to live.

    Dana - Thank you for forwarding that along! I've seen your comments on a number of related posts, so I might reach out to you privately. The builder in your link looks like he ran afoul of the law in MA in the recent past. His old website is down, and he appears to own and operate a similar-named company in NH, now.

    1. Expert Member
      Dana Dorsett | | #5

      Sorry to hear that Carter Scott may have gotten in over his head on a development (that happens to many developers, not just him.)

      It's possible to cost-effectively retrofit a house to reasonable comfort levels and energy use levels capable of being heated with a reasonable amount of ductless or ducted heat pump and still be well short of a DER.

      The only DER I've been involved with in MA sprang out of the owners desire to add enough solar to offset most of the utility costs on a 3-family house in Worcester (99% outside design temp =+5F). The shading factors and roof angles made that goal a complete non-starter, but at the time one of the larger utilities was subsidizing DERs. Operating as his own general contractor we developed a strategy to meet the program requirements without completely breaking the rehab budget using large amounts of reclaimed polyiso on the exterior along with spray foam in the balloon framing. (I kept lobbying for using cellulose in the framing, but the foam quotes came in cheaper than dense packing, and made air sealing the plank sheathing a lot more robust.) The house is heated with one ductless heat pump per unit (3 floors, 3 Mitsubishi FE18s, no backup.)

      Even with the reclaimed foam saving well over $10K in upfront cost it would have been unaffordable without the subsidy from the utility.

      My current home (also in Worcester) has ~2400' of above grade floor area, and ~1600' of unfinished basement, all with a very inefficient shape (14 corners to the footprint, hipped roofs broken up by two gabled dormers and one shed dormer.) Since my moving in the 2x4 walls have been dense packed cellulose, R20-ish average insulation has been installed in most of in the 2x6 raftered roof (still has about 350 square feet of cathedralized ceiling to go requiring a full gut of the upstairs ceiling), the basement walls have been retrofitted with 3" of reclaimed roofing polyiso. Most of the windows are the 1920s vintage original wood sashed single panes with 1980s vintage clear glass storms.

      At the current building envelope level the heat load is low enough that it COULD be reasonably & comfortably heated with a couple of half-ton Mitsubishis (one in the large upstairs finished attic room, the other in a lossy family room with too many windows) and a 1.5 ton Fujitsu slim-duct mini-split married to the original duct system (originally a coal fired hot-air furnace, converted to oil at one point, then a gas furnace in the 1960s followed by hydro-air at some point in the early 1990s.)

      The total cost of installing the ductless and ducted heat pump equipment would be around ~$15K, which is FAR less than it would take to do a foam-over, reglazing with U0.20 windows, and new siding (most of which is original 1920s nine inch exposure clapboard in good condition.) As it is, the gas boiler driven hydro-air zone rarely runs whenever the wood stove is burning, the lossy family room has hydronic radiant floor. Since the wood stove is in the larger space with the thermostat for the hydro air, the upstairs and a couple of the rooms doored off from the wood stove area ran cold whenever the wood stove was burning, and have been DIY micro-zoned using reclaimed cast iron radiation for less than $2K additional expenditure. The inverse indirect water heater that originally served as a buffer for the radiant floor and the hydro air made the micro-zoning pretty straightforward.

      It is not the most comfortable 1920s house in central MA, but it's really not bad, and still a LOT cheaper than a DER!

      At some point the 1990s vintage clear glass double panes in the family room will be reglazed with something higher performance, and we're going to bite the bullet on the cost 5" of reclaimed roofing foam when it's time to re-roof (mostly for ice-dam control) despite the fact that most sheets will have compound angles. Some of the original windows are in rough enough shape to be worth replacing at some point too, but as-is the comfort levels are fine, and it could indeed be heated & cooled with the aforementioned R410A refrigerant heat pumps, no question.

      At a design water temp of 125F for all the radiation, when bigger-better CO2 refrigerant heat pumps arrive the boiler could simply be be replaced and the heating system could continue to operate without much modification. As is it would take three Sanden heat pumps to have sufficient capacity, and would require significant system modifications to work. I've considered using a single Sanden for the micro-zoned room & radiant floor, and 1.5 ton Fujitsu in place of the hydro-air, but the heat load math puts it a bit close to the edge, especially if using the Sanden for domestic hot water too (which is what it's original purpose was).

      Bottom line- with judicious retrofit tightening & envelope upgrades, by doing the basic heat load math it's possible to make even inefficient house designs like what I'm living in pretty comfortable with micro-zoning with right-sized low-temp radiation, at a far smaller budget than a DER.

  4. GBA Editor
    Martin Holladay | | #4

    Q. "Will solar panels and air-source heat pumps alone make an older, poorly designed home comfortable to live in?"

    A. Of course not -- and no one at GBA has ever said they would.

    Q. "Every house I've ever lived in has had comfort problems - some hot rooms and some cold ones, condensation on window interiors in the winter, they're either really dry or face moisture problems in basements."

    A. It sounds like you need to talk to a home performance contractor or a weatherization contractor. The problems you describe can usually be solved with work that is considerably cheaper than a deep energy retrofit. You would probably start with blower-door-directed air sealing, storm windows if necessary, and adjustments to the home's heating system to ensure that the heat delivered to each room matches the design heating load.

  5. Expert Member
    Peter Yost | | #6

    HI Dabash -

    You should contact Steve Baczek, a leading high performance architect in Reading MA. He may be able to work with you directly or recommend builders you should consider:

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