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What makes the most sense for an energy efficient bungalow rehab?

user-1151096 | Posted in Energy Efficiency and Durability on

Hello everyone,

I’m embarking on a gut rehab of a 1908 bungalow in southeastern Vermont with a very limited budget. It’s 1,000 sf on the first floor and 500 on the 2nd floor attic space. To get a construction loan, I’m in a crunch to get estimates and a scope of work in a very short amount of time. I’m feeling as though I should fasten my seatbelt! I just started working with a green builder and would love to hear from the GBA community on a few key issues.

My vision: Although I may not be able to afford it this year, I would like to renovate with an eye towards using PV for an all-electric home after making the shell as tight as possible within my budget. I also value simplicity. With that in mind, here are my ideas and questions:

1. Roofing: Although I haven’t seen the numbers yet I assume metal standing seam is more expensive than asphalt shingles. If the price different isn’t huge, I would go with the metal since I was told that PV panels attach easily to standing seam and there are no roof penetrations which is a big advantage. Other pros/cons I should think about? The builder recommended 3 ½” of poly-iso on the exterior of the roof boards and dense pack cellulose on the interior, but that still doesn’t make R-49 so we need to see what’s doable . The bungalow has true 2×6 rafters. Suggestions?

2. Insulation: The walls are true 2 x 4s and again I wanted to use dense pack cellulose with some type of thermal break. I’d love to have double stud walls, but I think that would break the bank. I definitely want to keep spray foam out of the house. With that said, the builder recommends spray foam for the foundation walls. Above grade they’re brick and below, stone. While I understand the importance for air sealing and moisture management, I wish there was another way to accomplish this without using spray foam. Any other options here?

3. HVAC: There’s no natural gas in the area. After reading some of Martin’s articles I’m toying with the idea of an air source heat pump (ductless mini-split). Will single source heat work sufficiently? Two units on one compressor? So far when I’ve mentioned ashp no one seems to have had experience with them so the waters feel a bit uncharted. Would a small ashp do the job in climate zone 6? Any recommendations for one that’s also very quiet? I’m hearing that propane and oil is now as expensive as electric for heat, but I just want to make sure I’m not going to carry a higher (electric) heating bill until the time I can afford PV.

4. DHW: From one of the GBA articles/blogs that I read it sounds like a heat pump water heater would also reduce the electric load. It could go in the basement. Does this make sense? Do these have sone ratings associated with them since I’m sensitive to noise levels and this may be right under the bedroom.

5. Windows: Lastly, the current windows are single pane with storms. At first I was going to replace them, but after talking to a few folks I started rethinking it. I talked to someone who refurbishes old windows by inserting a gasket on 3 sides of the sash for an airtight seal. He removes the weight form the top sash, making it stationary, and then adds rigid foam to the back half of the chase where the weights are. It’s a lot less expensive than new windows and retains the bungalow character so I’d like to keep them after all. What’s U factor of single pane with storms? Thoughts on the impact of this on the overall tightness of the house? I’ve always read to replace windows last and that air sealing/insulation are where the money should go. Agreed?

I’ve feel as though I’ve asked more than my fair share of questions, yet I’d greatly appreciate any thoughts or insights to keep me on a sustainable, practical and frugal path before I go too much further!

Thank you one and all!
Theresa

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Replies

  1. homedesign | | #1

    If I lived in Vermont... I would hire Robert Riversong as a Design consultant
    [email protected]

  2. dickrussell | | #3

    A GBA blog on heat pump water heaters is here (you may have seen this)"
    https://www.greenbuildingadvisor.com/blogs/dept/musings/heat-pump-water-heaters-come-age

    I have to wonder if your Vermont location is appropriate for a HPWH. As noted in the blog, it will rob heat from the basement air, which must be made up either by the heating system or by ground heat leaking in through the (uninsulated?) walls and slab in winter, a situation that could result in a basement uncomfortably cold for any purpose but storage. In summer, the cool basement walls and contents will be all the cooler, with more condensation of humidity from ambient air and perhaps more musty smelling.

    A single pane window with clear glass storm will give an overall U of around 0.5, according to the references I looked at briefly. I'm inclined to agree with you on your thinking about window replacement vs fixups. Air sealing always pays off well and provides the best return for an older house.

  3. wjrobinson | | #4

    Theresa, as John said, hire design services. Reading all here, I think you are getting a bit confused. Some ideas are conflicting with your wants, some are bad for your location. You are trying to build a new home out of an old cute home. In the end this can be done. But, it is not economical so the whole idea flies in the face of your budget wants.

    IE, I want quiet and I want a noisy water heater. Which do you want more? You can't your whole list be against itself. I want to keep windows, keep price low and make them super efficient. Well, I can't do that. And to top off your budget busting plan, your last want, solar will add another say $15,000. Time to work up your spreadsheet of costs. Then multipy by 125% if trying hard to stay on budget and if you like buying more as you shop add 150-200%. These are real over runs I have had clients do time and time again. So in my world it is a fact that customers toss budgets aside the second day construction begins.

    Riversong may be able to help you tremendously and for a very fair price. Contact him.

  4. user-1151096 | | #5

    John, Dick and AJ,

    Thank you all for sharing your thoughts with me. I have read posts by Robert for a while and I like his approach. Although he's in VT, he's 2 hours away, but I'll contact him and see where it leads.

    To AJ's point that there are a lot of conflicts, I think it sounded worse than it is. The house is an estate sale and badly neglected. It needs to be gutted (homasote walls in bad shape) and the roof needs replacing. Currently there is a very old oil furnace for heat and the ductwork is filthy so it will have to be replaced, too. I was looking for an alternative to fossil fuels and had read Martin's article https://www.greenbuildingadvisor.com/blogs/dept/musings/heating-tight-well-insulated-house on ASHP min-splits and how they are now suitable for temps below zero and are in use in VT and doing well.. I realize their adequacy is dependent on having a tight, well-insulated and small space - which I think the bungalow will be (with the exception of the window U-factor). This is what I was basing my thought on.

    Dick, thanks for the link to the HPWP article. When I re-read it, I noticed the noise issue which I hadn't remembered..

    Most of my budget will go into the envelope, air sealing/insulation and a heating system. The interior will be very simple. The challenge is figuring out where the dollars are best spent and what's the optimal insulation plan.

    Thanks again.

    Theresa

  5. wjrobinson | | #6

    Theresa, great followup post. I am all for doing all that you can to a home that is in such shape and that was purchased at a a highly discounted price. I think now you'll do a great job on a great worthy project.

    With PV and a PGH build, use standard electric water heater, one split air, pellet stove or gas fireplace for back up coldest periods.

  6. user-1151096 | | #7

    AJ - Thanks. I appreciated your post and recommendations.

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