Walls and/or what’s next
After air sealing and insulating 1) basement crawlspaces, 2) kneewalls, and 3) top attic – where next to focus our energies? 1952 house in Maryland CZ4.
Remaining weak spots:
1. R3 walls on large,long first floor.
N/W/E – beautiful stone exterior, original plaster. We could install SIPS and drywall interior to the plaster.
S – brick and aluminum siding. We could insulate this externally, with foam board and stucco.
2. R11 walls on second floor, and poorly insulated shed dormers. We could blow in cellulose and/or insulate externally, waiting until we replace the siding.
3. HVAC. We would rather focus on the envelope, but only within reason (ROI in 7-10 years). Thus, there is a point when it will make sense to transition to focusing on mechanicals. Per Dana’s suggestion, I’m engaging a RESNET HERS rater to model this.
Questions:
1. How much will addressing the walls lower our utility bill? These feel like more major undertakings than our current sealing/insulation projects. Please note there are many windows on the first floor, with some wall:glass ratios approaching 1:1.
2. Related: Would my son feel a comfort difference in upgrading to 2 high performance windows in his bedroom, relative to single panes+low-e storms? (Windows on W wall of house.)
3. Where should we focus next?
Thank you.
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Replies
Emerson,
I am sure someone will try to address your questions. In the meantime, you might want to search GBA for articles on "deep energy retrofit" to learn more about where to focus your effort.
Also...
Your Resnet Rater will have the advantage of being onsite with you during this process. He or she should be able to help you with prioritizing your expenditures.
Thanks Steve, much appreciated, will do.
Emerson,
Every house is different. The accurate answer to your question is: You have to do the math.
That said, it is highly unlikely that more energy retrofit work will be cost-effective in your climate -- beyond (I'm guessing here) blower-door directed air sealing and installing storm windows on any single-glazed windows.
The colder the climate, the more likely that energy retrofit work will be cost-effective. Maryland is relatively mild.
The worse the condition of the house, the more likely that you can come up with low-hanging fruit -- but you've already addressed most of the low-hanging fruit.
The more expensive your fuel costs, the more likely that additional work will be cost-effective -- but you don't live on an island off the coast of Maine where fuel is particularly expensive.
If you want to lower your energy bills, you might want to consider installing a photovoltaic (PV) system -- but only if your local utility offers a good net-metering agreement.
All of this said, a site visit by an energy rater or weatherization expert can sometimes result in an unexpected surprise and recommendations for important retrofit work -- so an audit is almost always a good idea.
Here are links to two articles you might want to read:
Deep Energy Retrofits Are Often Misguided
What Should I Do With My Old Windows?
One final point: You may want to pursue further energy retrofit work even if the work isn't cost-effective, either (a) to improve comfort, or (b) to lower your carbon footprint.
Martin,
Thank you for the links, and I will do as you suggest. I'm grateful for finding GBA these past several months - the knowledge and support from this community has been incredible.
1. Do you recommend installing low-e storms on all windows, ie both older single-paned and newer double-paned? Please see attached photo from first floor. We have several first-floor rooms with similar R3 wall: R1 window ratios as this (and these are also old wooden doors). Perhaps one sensible approach would be to add high performance storms throughout (ie, so all windows in house have 2 or 3 panes, thus enhancing the minimal performance of these very-glassy walls). Then, we could focus on HVAC in the next few years.
2. Where should I buy the low-e storms? Our contractor is a dealer for Provia, and we like him, but we really don't know the products. Priorities are of course high performance and bang for buck.
Emerson,
Great looking room. Are you going to keep the pot lights? If so, they would be high on my list for air sealing.
Thanks Steve. We love the space.
Great minds. We are using this last day of our staycation to visit the lighting store. The house has 40+ recessed lights, including 15 beneath a vented flat roof! Thus, we'd be looking at $400+ for LED conversions... so this is a great time to upgrade to cove lighting, or another non-recessed option. That way, we could also completely seal the ceiling. I'll post updates, if you are interested.
Incentive note: Our county provides a great tax break for 30% reduction in HERS scores in existing buildings. Given our major air sealing/insulation and recent upgrade from oil to heat pump hot water, I'm hoping we're at 30% now. Thus, I might postpone the lighting until after we've applied for the tax credit, so that I could re-apply for another 30% in 3 years (after updating lighting+HVAC+any appliances).
Emerson,
Q. "Do you recommend installing low-e storms on all windows, i.e. both older single-paned and newer double-paned?"
A. The answer to your question can be found in one of the articles I linked to ("What Should I Do With My Old Windows?"). In that article, I wrote, “If you are intrigued by low-e storm windows, there is a caveat: this type of storm window works well when installed over single-glazed windows, but should never be installed over newer double-glazed low-e windows. According to an article in Environmental Building News, 'Modeling performed for LBNL by sustainability consultant Thomas Culp, Ph.D. has uncovered the potential for serious overheating problems when low-e storms are added to low-e windows: in hot weather, in direct sunlight, temperatures up to 185° F (85° C) may be reached. That kind of heat can cause premature aging or failure of the insulated glazing unit’s seals.' ”
Thank you. I'm sorry I missed that detail.
If the double-paned window is NOT low-e, is it worth it to install a low-e storm? If the double-paned window IS low-e, should we install a non-low-e storm?
Emerson,
Q. "If the double-paned window is NOT low-e, is it worth it to install a low-e storm? If the double-paned window IS low-e, should we install a non-low-e storm?"
A. If "worth it" means "cost-effective," the answer is no and no. Again, those answers should be in the article I linked to. Storm windows are only cost-effective when installed on a single-glazed window.
Sheepish thank you. (I read the article and will return to it.)
Martin,
Wanted to update - had a wood window restoration expert here today, and this is how we will proceed (with her or another). She has a restoration shop and appears a real pro - recommends maintenance on most of our windows (removing from frame, removing debris, replacing, copper weather strips, etc) and custom wood low e storms for the windows that need storms. Cost would be higher than 50-70 for aluminum storms that is often quoted, but less than replacement windows. And our windows would then have 50-75 more years, while maintaining the charm of the house.
Thanks for the suggestions.