I had the luxury of a vacation in Maine at the end of last week, but the first part was at Summer Camp. No, I wasn’t making animals out of walnuts or rocks. Or learning how to build emergency shelters out of pine needles. I’m talking about the event hosted by Joe Lstiburek and Betsy Pettit have hosted an annual conference, the Westford Symposium on Building Science. Presentations on various building science topics by day, and mountains of food and drink and music (and more building science) in Betsy’s and Joe’s backyard.
The presentations are on the Building Science website. Here were some of the highlights for me, in sound bite form.
Lies, Damned Lies, and Modeling
Michael Blasnik kicked things off with a rollicking discussion of statistics, modeling, and myths.
- Ben Franklin: “There is nothing so horrible in nature as to see a beautiful theory murdered by an ugly gang of facts.”
- “Home Energy Score is more than 50% off, more than 50% of the time. I don’t think that should be their slogan”
- I’ll interject with an LBNL presentation on August 6 on the Home Energy Score, which goes right to an excellent point Michael made. From the abstract “When averaged across groups of homes, HES predicts energy use within 1% of actual consumption when physical characteristics and occupant behavior are well accounted for.” Uh, yeah. So, if you want to take a bath, and you stick one foot in near boiling water, and one foot in ice water, you should be just about right. Or not. Averages are OK for talking about populations, but deviations from the mean become very important when looking at individual homes. The Home Energy Score looks less compelling in that light–and remember, it’s scoring individual homes, not populations.
- A homes previous occupants’ energy bills are a better predictor of natural gas use than energy modeling. (And should be less expensive to get!)
- Complicated models don’t lead to better results.
- Some things that are hard to model: foundation heat loss, infiltration, wall and attic heat loss, window loss and gain, and HVAC performance. In other words, it’s hard to model homes, especially existing homes!
- As we’ve imported more lemons from Mexico, traffic fatalities in the U.S. have decreased. (Illustrating that correlation does not imply causality.)
A Tale of Two Cities
Mike Steffen compared two buildings, one that was designated LEED platinum, and one that was less expensive to build and uses a lot less energy.
OK, the buildings are very different, with different end uses. But it just may be that the glass walls aren’t as an efficient design.
Interestingly, in the primary case study, the building had one floor with dual-flush toilets. That floor’s water use was 14% higher than the other floors!
In Hot Water
Gary Klein’s presentations on hot water are eye-opening. If you’ve never considered how plumbing design impacts water usage—and it seems most haven’t—a few hours with Gary can change that.
- “It does not make sense to discuss efficiency if you are not providing the service people want.” While Gary was talking about delivering hot water to the tap in about 4 seconds, that same statement applies to most of residential energy efficiency.
- On motivating customers to save: If it isn’t (at least) 10% of your mortgage cost, you’re not going to pay attention.
- Average shower usage is 14 gallons with a standard deviation of 9! (Hard to model that and expect accurate results in an individual home.)
- While waiting for hot water to arrive, the lower the flow rate of the fixture, the more water is wasted. This is a function of water velocity, and heat transfer to the pipe. This does NOT mean that low flow fixtures waste water. Once the water arrives, and depending on usage, they use less. And how long you have to wait for the water is the big driver.
- It’s the feel, not the flow. Some low-flow fixtures feel better than others. Back to that service issue, let customers pick the (low-flow) fixture they like.
- Things that reduce hot water use: Insulating hot water supply piping; end uses closer to water heater(s); lower flow rate plumbing fixtures; lower volume plumbing appliances; using waste heat running down the drain to preheat cold water; truly “Instantaneous” water heaters; warmer incoming cold water; Structured Plumbing®
- (You’ve got to learn about structured Plumbing!)
Case Studies in Building Commissioning
Kent Browning discussed tales from the front, with good examples of the unfortunate reality.
- The thermal enclosure of the building IS a part of the mechanical system. (Go figure!)
- Commissioning is not the punch list or test and balance report.
- Kent’s discussion of problems at a senior center, including disconnected returns, and Swiss cheese fire walls, requiring more than $1M to fix, and moldy books in a new library pointed to problems with the way stuff gets built.
Food and Drink in Joe’s and Betsy’s Backyard
I won’t even attempt to cover this—suffice it to say that there was more than ample on both counts, and the quality was top notch!
Building Science Myths. And Air Leakage Math. And WUFI.
Achilles Karagiozis kicked off Wednesday morning with a very funny WUFI modeling of an igloo—a great way to wake people up in the morning after the aforementioned food and drink and the late night music by the band. However, Joe’s quick rebuttal, pointing out that people had been making igloos just as well without modeling while said in jest is an important point. Maybe we don’t need modeling for everything? (Actually, I don’t consider that a question. The statement: we don’t need modeling for everything.)
- Dr. Karaiozis dove deeply into test data, including some inconclusive and seemingly contradictory finding, and geeked out on the math (and I love math!) but brought us back to the conclusion that an air space behind cladding benefits walls by increasing drying potential.
- Joe Lstiburek jumping in: “A small air gap behind a painted cladding doubles or triples the life of the paint”
- Crushing the heat recovery myth that’s been sneaking into some conversations. Yes, there is some heat recovery as air leaks through insulation. But that heat had to come from somewhere, and it’s still a net loser. “You do not want to have leaky walls… Absolutely not. Makes no sense.”
The Thermal Metric Project
Chris Schumacher and Dave Ober reported on research over the past seven years—and frequently discussed at Summer Camp—around the possibility of a new metric to replace R-value.
- There was a lot of discussion of the methodology of the testing. I found the presentation of the impacts of temperature and air-leakage fascinating.
- Mr. Ober shared some nifty but rather complicated ways to present the new metric, from line graphs to tables bases on climate.
- Ober, paralleling Dr. Z’s comment above: ALL air leakage increases energy use. (tho’ interaction between convective/conductive heat flow means use less than predicted).
- “Walls with higher insulation levels exhibit reduced heat flows and energy use” but more sensitive to air leakage. In high r-value walls, air leakage has bigger degradation on r-value, and moisture is a bigger deal.
- This was a great discussion that helped refine understanding of how insulation works–however in the built environment, and channeling Blasnik’s discussion of it’s still fair to ask whether the new metric would improve modeling.
Joerg Birkelbach discussed compression gaskets and their ability to stop water and air flow.
There were a lot of good examples of how these compression gaskets can be used, and how they can be better than goopy stuff applied by people not paying attention.
Don’t heat up cans of foam—there is a very dangerous explosion potential!
Combine a very well-insulated crawlspace, a growing number of people, many bottles of good wine to pass around, and Joe Lstiburek trying to answer questions in 140 characters or less, and you’ve got the 5th annual Summer Camp Crawlspace interview.
Hopefully Peter Troast of Energy Circle will again summarize the entire interview. (See the 2012 interview, for example.) But here are some of Joe’s responses (without the questions):
- The most useful part of a blower door test is as a marketing tool
- A fallacy of people doing modeling – you need models to establish standards
- All of the best things I’ve done have come from other people.
- Is energy the most important thing? No, love is.
- Passive House is the only place where real innovation is happening.
Fluid Applied Membranes
Marcy Tyler and Ed Retzbach talked about applications for and testing of fluid applied membranes. This is the Summer Camp session I was most looking forward to, and unfortunately, also the biggest disappointment. I wanted to learn specifics about what can be applied to what surfaces, interactions of membranes with different goops and goos, conditions where application does and doesn’t make sense. There where some examples, but little that I could walk away with.
We got a quick overview of German buildings from Andreas Holm. Some of the factoids:
- The German economy grows “despite” reducing energy use during the same period. Maybe energy productivity is as important as just raw energy use?
- 80% of German buildings are ventilated passively with windows. (Interesting in light of the ASHRAE 62.2 discussion!)
- 60% of German buildings made with solid masonry walls.
- The energy savings potential of retrofit exceeds the energy potential of green technologies in Germany—and I daresay in the U.S., too. (One home at a time…)
- 50% of insulation used in Germany is Rock Wool—with a new innovation of adding aerogel to the rock wool to significantly boost performance!
- And speaking of adding stuff, in Germany 85% of all EPS has graphite which decreases thermal conductivity by 14%.
- Paint is not an insulating material.
- Nice quote: “It doesn’t matter if you calculate it on a computer or an envelope, as long as the calculations are correct.”
- Dr. Holm showed an innovative product, EPS foam with ventilation cavities designed to be run on the outside of the house, beneath another layer of EPS. Innovative, yes, but I’m skeptical…
Sucking and Blowing and ASHRAE 62.2
Joe Lstiburek teed up the release of BSC-01, a residential ventilation standard in opposition to ASHRAE 62.2 2013. Allison Bailes of Energy Vanguard has done a great job summarizing the debate and interviewing key actors. See his interviews with Joe Lstiburek and ASHRAE 62.2 Committee Chair Paul Francisco, and the embedded links for excellent background. Later this week, I’ll share my view of what the answer should be. (Update: See “Residential Ventilation: Why I like BSC-01 better than ASHRAE 62.2 2013“.) In the meantime, here are some of Joe’s points:
- ASHRAE 62.2 rates have doubled with the 2013 version. Doubling is a big number. And there are big costs (in terms of performance not just dollars).
- Ventilation rates are based on odor control, not formaldehyde or other contamination concentrations.
- Quebec tracer gas study shows you can’t ventilate at a high enough rate to control formaldehyde.
- There isn’t anybody on the [ASHRAE 62.2] committee who actually designs & installs ventilation systems.
- A single point exhaust with random infiltration points is not the same as a balanced mixed ventilation system.
- At ASHRAE 62.2 2013 rates a typical 2,000 square foot house requires 90cfm. This creates part load humidity, dryness, and high energy-use problems.
- Occupants should have control.
If you’re lucky enough to get the invitation, Summer Camp is time well spent, for the formal presentations, the equally good informal conversations, and the fun!
(Addendum: One of the things that makes Summer Camp even richer is the real time tweeting by a number of folks, adding comments, links to related info, and it must be said an element of fun. Check out the Twitter thread #bscamp. Thanks to
and many more!)