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More Musings of an Energy Nerd
A subset of North American builders has been interested in a high-performance homes for at least 40 years. You could call these people green builders, progressive builders, or energy-conscious builders; whatever you call them, they’ve been around for a while.
When these gray-haired builders get together, they sometimes ask each other, “Are things getting any better?” The oldest members of this group — those who have been urging builders to pay attention to airtightness since the mid-1970s — know that many of today’s builders are making the same construction blunders that were being made during the Jimmy Carter years.
To get some perspective, I recently went to my bookshelf and pulled out issue #1 of Energy Design Update, a monthly newsletter first published in July 1982. It’s fun to re-read this old periodical, which happens to include William Shurcliff’s review of The Superinsulated Retrofit Book. (In his review, Shurcliff outlined a debate that’s still with us: “To bring an old house up to the energy-conserving standards of a new superinsulated house requires a many-pronged attack that involves not only the walls, windows, and doors but also the basement, foundation walls, and attic or roof. … Is it really cost-effective if the annual saving in fuel bills will be only about $500 or $1,000?”)
Much of the advice published in this 34-year-old newsletter is still relevant today:
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24 Comments
Recessed can lights
Contractors in my area consider the recessed can light problem to have been solved by improvements in the can lights themselves which are now insulation rated and use LED bulbs. They just shake their heads at my insistence on limiting can lights to areas with a floor above.
Response to Reid Baldwin
Reid,
Good point. I agree that the new LED pancake lights are likely to be part of the solution to this problem. However, I suspect that far too many of the old high-style can lights are still being installed.
Can lights and attic ductwork
Can lights are clearly still in favor and properly air sealing and insulating around them continues to be a labor intensive part of most new construction jobs for conscientious contractors in our area (Midwest, zone 5). Unfortunately, more often than not, we see blown fiber insulation around IC rated cans with no attempt at air sealing. Most builders just don't care.
The same goes for ductwork, which is often unsealed. There are outstanding HVAC guys who do an excellent job but they are still the exception. In some instances we have remedied the problem by encasing the ductwork in sprayfoam but again it boils down to cost.
Feedback from Michigan
This is based on my experiences as an involved homeowner - not a building professional. I cannot comment much on trends since what knowledge I have of building science is recently acquired.
1. Either builders are doing that ok or I am not knowledgeable enough to spot the problems. (The later is probably more likely.)
2. Builders have succeeded in keeping the blower door testing requirement out of the code here.
3. Most builders install code minimum windows, but the code levels have improved.
4-5. No personal knowledge.
6. My builder, who I believe is one of the more conscientious in the area, proposed exactly the basement insulation you mention.
7. This may actually be getting worse as the heating and cooling loads drop and they keep sizing based on "years of experience."
8. No personal knowledge
9. This is uncommon here since most people have basements. However, my apartment is one of the few buildings I know of built on a slab. Guess where the ducts are - in the attic.
10. See above comments
11. Non-existent or poorly implemented mechanical ventilation may not make the top ten list yet, but it will probably climb the list as more progress is made on the air leakage issue.
Response to Torsten Hansen and Reid Baldwin
Thanks to both of you for your feedback, which isn't very hopeful. It seems that it's really hard to change the direction of residential construction.
Codes can help
Massachusetts communities had the option to adopt a Stretch Energy Code starting in 2010. The Stretch Code requires that new homes less than 3000 sf achieve a HERS rating of 70 or better, and homes 3000 sf or greater achieve a HERS of 65 or better.
In my community of Newton, over 300 new homes have been built since the Stretch Code went into effect. Builders have achieved HERS ratings on those homes much better than what the Stretch Code required: three quarters of the ratings were below 60, and a large number were in the 40-50 range. Apparently, a lot of HERS rating improvements can be achieved with little or no added cost.
I realize a low HERS rating does not guarantee a good house. For instance, based on first-hand observations as I walk my dog around a neighborhood where many of these homes are being built, I'm worried that there will be premature siding and trim failure on many of them because the better insulation has not been accompanied by better water management details.
But it's hard to get a HERS of less than 50 if you screw up items #2 through #10 on your list (with the possible exception of #6 and #7). I suppose in some cases builders may be getting low HERS ratings as a result of bad HERS raters, but I think that's a small minority of cases.
MA policy makers are now in the process of developing and getting approval for the new Stretch Code, since IECC 2015 (not yet in force as the base code in MA) will come close to the current Stretch Code. It's leading to some interesting conversations, including about possible requirements for solar-ready roofs. That would start to address the problem of countless new homes (close to 100% in Newton) that are being built in a way that will basically prevent solar panels from ever being installed.
My take-away is that aggressive codes can work -- not only to reduce the carbon footprint of new homes (as is the goal of the Stretch Code), but as a quality control measure and a consumer protection strategy.
Response to Paul Eldrenkamp
Paul,
Thanks for sharing your encouraging story. I agree with your assessment: in areas of the country with more stringent building codes -- and, importantly, some mechanism for code enforcement -- houses are getting better.
Vermont has an excellent energy code, but following the code is almost entirely voluntary. We have almost no mechanism for code enforcement (outside of the town of Burlington). Many Vermont builders are totally unaware that our state even has an energy code, because no official has ever visited one of their job sites to talk with them.
help with code enforcement
With the Stretch Code, the building officials can hand off a whole area of enforcement to the HERS rater. In general, I think this is a good idea.
Response to Paul Eldrenkamp
Paul,
I agree. If builders were required to get a HERS rating, quality would ramp up quickly.
Job Security
California requires energy calcs to comply with Title 24; these can be so complex many builders pay to have it done. They encompass efficiency in HVAC systems; ventilation; lighting including outdoor lighting; and solar power. Builders are also doing more toward air tightness. Sand below the slab and above the poly is still a standard practice however (in my limited experience).
The article and comments above all illustrate the value and importance of this website. I have always invested in self-education about my craft and trade, and Green Building Advisor has been the go-to source for the last many years, along with BuildingScience.com. I have not found anything else that is as consistently enlightening and reliable, and accessible, and current. Being a paid subscriber has given me hugely significant returns.
I'm sorry Martin if in researching this issue you were looking for an excuse to retire!
Response to David McNeely
David,
I'm glad to hear that GBA has been useful. You're certainly right that anyone involved in fixing energy and moisture problems in single-family homes will have plenty of work for decades to come.
Slab on Grade Edge Insulation
Yep, definitely still a problem. I investigated a brand-new construction townhome in Massachusetts; big national builder construction. Their slab edge detail, um, fails to insulate the slab edge. Result--seriously cold edge of slab, bad enough to cause condensation and wood floor issues in some high humidity units.
I've also seen a similar detail in 1990s/2000s construction, but I would have thought that "Darwinian selection" would have improved this by now. Ah well.
Response to Kohta Ueno
Kohta,
Thanks for sharing the detail. It seems that the architect didn't care very much about keeping the occupants warm -- but was very, very concerned about keeping the crushed stone under the slab from getting cold.
When I see a detail like this (which, considering the fact that you had that detail drawing handy, was evidently on the original plans), I wonder: Where were the building inspectors that day?
I don't really understand this drawing.
If I am reading this correctly, the insulation should have been on the outside of the wall extending below frost depth?
What would the purpose be for the insulation on the inside corner of the slab anyway? Was there some reasonable explanation for the insulation in that spot?
Response to Lucy Foxworth
Lucy,
This is a joke made by Kohta Ueno, an engineer. The butt of the joke is the architect who made the drawing.
Believe it or not, engineers like Kohta get to chuckle all day when they review architects' plans. I'm pretty sure that this is a real architectural detail, made by a professional architect who spent several years at a school of architecture.
There is no rational explanation. Architects' brains are different from ordinary brains.
No wonder I didn't get it.
Engineering jokes are a little beyond me, despite the fact that engineers are famous for their sense of humor.
Architects
Q: Why are architects banned from Heaven?
A: Jesus was a carpenter.
BSC's Slab on Grade Recommendations
In case this clarifies anything, BSC's recommendations for new construction slabs can be found here, in Figure 1:
BSI-059: Slab Happy
http://buildingscience.com/documents/insights/bsi-059-slab-happy
The insulation both (a) covers the edge of the slab, (b) extends down the stemwall, and (c) runs horizontally 4 feet. The stemwall insulation keeps the gravel/soils under the slab warmer than unprotected conditions--per Joe's guidance:
Ah! More engineer humor
Most times I can get Dr. Joe's humor.
Insulating foundations in CZ3
We've found that in our high-performing houses in CZ3, when performing load calculations for uninsulated slab on pier foundations, we get 30% losses of heating loads. On Pier and beam foundations with insulated conditioned crawl spaces, the loses are in the teens.
LBNL Diagnostics Database hidden feature
Martin, thanks for this. One more feature of the online version of the LBNL Residential Diagnostics Database is that it allows you to enter a home's characteristics and it will give a sense of where that building's envelope leakage falls among its peers. I've found this useful -- maybe others would too?
Response to Chris Stratton
Chris,
Thanks for the link. That's an interesting online tool to play with.
Cheap mentality in the industry
1. Every project starts with a full set of DETAILED plans and specifications, and all plans and specs should be designed and developed by an EXPERIENCED and EDUCATED Designer or Architect. Lord forbids they may have to pay more than $1/sf. Pay now or pay later!!!
2. Hire a professional tradesman, not the lowest bid.
3. "Stupid is as stupid does"
Kohta - who let you in my
Kohta - who let you in my house to take those pictures?
I stopped by a house near me that is currently under construction are saw some sloppy work.
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