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More Musings of an Energy Nerd
Every day, marketers convince hundreds of people to spend money on useless “energy saving” gadgets. Since these marketers show no signs of going away, it’s time to highlight their products with a ten-worst list.
The order of the products described in the following list is random. I had to remove an eleventh item from this list: “insulating” paints, a product category that I debunked in a recent blog. If you know of a deserving product that should have been included in this list, feel free to post nominations for the list’s second edition.
The Ten Most Useless Energy-Related Products
1. Tyvek ThermaWrap
In 2006, this “low-e” housewrap suffered from a disastrous launch by bumbling DuPont marketers who bragged that the “insulating” properties of the housewrap were due in part to its low emissivity. Reviewing the product for Energy Design Update, I asked ThermaWrap representatives to specify the emissivity of the membrane, only to be told that “due to company policy,” DuPont was “not at liberty to reveal the actual emissivity number for Tyvek ThermaWrap.”
Later, when my journalistic investigations revealed that DuPont had failed to produce a ThermaWrap fact sheet as required by the Federal R-Value Rule, DuPont reluctantly admitted that ThermaWrap has an emissivity of 0.2 — exactly the same value that EDU predicted in its September 2006 review. The emissivity of ThermaWrap is too high to qualify as either a radiant barrier or a reflective insulation.
DuPont no longer repeats its earlier claim that “Tyvek ThermaWrap changes the dynamics of heat flow across the entire wall system and dramatically helps improve the insulating value of the wall system.” In fact, if ThermaWrap is installed facing an air space, it will change the R-value of the air space from R-1 to R-2 — a change that few would characterize as “dramatic.” In…
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88 Comments
thermostats
I think this is a pretty good list, but I'm not so sure about programmable thermostats., yes, there are some studies that show no impact on energy use but there are also studies that show savings. The Philadelphia Gas Works low income weatherization program has produced significant savings from thermostat installations based on multiple impact evaluations (that I performed). The thermostats paid for their installation costs in 1 year or less. There was also a study by a group of gas utilities (Gas Networks) that found savings for customers receiving rebates for thermostats.
I think the impacts will be determined by the context. If the thermostats can make setback more likely or consistent, then they will save energy. If someone would have practiced setback manually without the thermostat, then of course there won't be savings.
KVAR
If the KVAR unit does not work, how do you explain residential bills I've seen that show a significant savings by utilizing one?
Thanks for the information
Michael,
Thanks for citing new studies that show that programmable thermostats can result in energy savings. I imagine that these studies included homeowner education; without the education, programmable thermostat installation programs don't have a good track record. That raises the question: what if a program provided information on the advantages of thermostat setbacks without swapping any thermostats?
Here are excerpts from two Energy Design Update articles — perhaps somewhat out of date, but still relevant:
EDU, November 2000: “An Unexpected Setback for Programmable Thermostats”
New field studies from Wisconsin and Florida suggest that programmable thermostats aren’t the prodigious energy-savers we’ve been led to believe and may in some situations actually increase energy use. “Before we did this study, I was sold on programmable thermostats,” says researcher Monica Nevius with the Energy Center of Wisconsin (Madison, Wisconsin). “It was a shock to me when we discovered that they have virtually no effect on energy savings.”
In 1998 and 1999, Nevius and fellow researcher Scott Pigg surveyed 299 homeowners in Wisconsin, constituting a representative sample of the state’s population and housing stock. As shown in Table 1, about two-thirds of those surveyed used manual thermostats to regulate their heating systems, while the rest owned programmable models. In-depth personal interviews were subsequently conducted with 30 of the homeowners to probe their personal attitudes toward energy conservation and thermostats. In fact, one of the main purposes of the study was to find out how homeowners’ attitudes toward energy conservation affect the way they use their thermostats and other energy-related behavior.
The results suggest that the owner’s attitude toward energy conservation is much more important than the technology. “We found that homeowners who are inclined to set their thermostats back will do so regardless of the type of thermostat they own and those who are not so inclined won’t do it regardless of the type,” Pigg explains. “Forty percent of the homeowners with manual thermostats set their thermostats back. Those who don’t aren’t eager to have a programmable thermostat and probably wouldn’t use one if they had it.” ...
Even Worse Results in Florida?
Preliminary findings from a Florida study on programmable thermostats appear to be even more negative than those from Wisconsin. Researcher Danny Parker, with the Florida Solar Energy Center, tells EDU that he’ just completed a field study for Florida Power Corp. (FPC) that monitored the end-use heating and cooling in 150 homes and broke out the results according to the type of thermostat installed.
“Within our project, we had 19 homes with programmable thermostats that showed evidence of increased consumption and peak demand,” Parker says. “This is just the opposite of what the HERS rating and Energy Star Home Program now estimate.” Parker says that he measured interior temperatures and space-cooling demand profiles at 15-minute intervals and found that people with manual thermostats were “much more likely to set up their thermostats than those with programmable models — just the opposite of conventional wisdom.”
Part of the problem, apparently, has to do with that old bugaboo: complexity (or, if you prefer, the “technological nuisance factor,” which is what keeps a lot of people from programming their VCRs). The manual thermostats are easy to operate and set back, Parker theorizes. But people with programmables tend to leave them at a constant setting because they’re too hard to program.
* * * *
EDU, January 2001: "Surprise! There are People Inside Those Buildings — Or, Why Programmable Thermostats Don’t Deliver the Promised Savings," by Craig Conner
A large field study conducted by Pacific Northwest National Laboratory concluded that the energy savings delivered by programmable thermostats are significantly less than advertised. Our findings square with those documented by the Energy Center of Wisconsin and reported in the November EDU. We concluded from our work that the value of programmable thermostats has been greatly overestimated because the mere presence of the thermostat doesn’t necessarily alter the homeowners’ behavior. In fact, our measured data suggests a nearly equal probability of setback with and without programmable thermostats. In short, the occupants control the thermostat and not the other way around.
More information, please
Dear Anonymous,
Your claims don't amount to much without a few more details.
1. What's your name?
2. Were the homes you're talking about enrolled in a study?
3. If these are anecdotal reports, they don't mean much, since utility bill vary from month to month and from year to year for a wide variety of reasons.
Great list
I'm delighted you stood up and exposed these products. Some are downright scams. I'd love to see you do a 10 best as well.
attic ventilators
I appreciate your list but I would make one caveat to attic ventilators. I live in an older home (75 + yrs old) and have vents directly in the attic walls. I installed an attic ventilator to help keep air moving and reduce the tempurature in the attic during hot summers days when wind speeds are low to non-existent. It does a decent job of performing that task without drawing much air from the conditioned spaces. I will not make any claim about reduced energy usage or cost savings though it does seem to help with water vapor / humidity in the attic space. To that end I would not say it's useless. Then again I may just be rationalizing a foolish exercise. Thanks for the article.
thermostats
The thermostat studies you cite actually don't address the issue very directly. The real question is -- if I install a setback thermostat, will I save energy? The two studies you cite did not look at differences in energy before and after installing a thermostat in a home, but looked at different homes and concluded no real difference in usage by thermostat type. Since many homeowners simply have whatever thermostat was already in the home when they bought it, such comparisons don't tell you very much.
The Gas Networks study I mentioned did not have any education component -- it was an in-store rebate program. The Philadelphia study did have in-home installation, but all homes were educated about reducing their setpoint and managing temperatures. For customers who wanted the thermostat (about 65%) the energy savings were much larger.
I think the before/after energy usage comparisons are much more powerful than the studies that simply look at differences between homes.
How much air is escaping through your ceiling?
Chuck,
You wrote that your powered attic ventilator "does a decent job of performing that task without drawing much air from the conditioned spaces." Here's the problem, though: it's almost impossible (without performing a blower door test on your house) for you to determine how much conditioned air is leaking through your ceiling into your attic. A tremendous amount of air can be leaking out that way, sucked by your fan, without you noticing. You won't necessarily feel any drafts.
A good summary of the problems associated with powered attic ventilators can be found in a fact sheet ("Effective Attic Ventilation") prepared by the Dominion energy group. The fact sheet notes, in part:
"At some point, the original purpose for attic ventilation was forgotten and/or replaced, in cooling climates, with the belief that it was to reduce roof and attic temperatures, thus lowering cooling expenses and increasing shingle life. This was further compounded by the leap of faith that increased or powered ventilation would be even better. While sounding logical, there is simply no research to validate it. In fact, scientific testing has shown that attic ventilation has almost no effect on roof surface/ shingle temperatures and very little effect on attic temperatures. There is however, a growing list of research, computer modeling and field data that indicates powered attic ventilation can be a detriment to health and safety and actually increase cooling costs."
Good point, Michael
Michael,
Good point about the three studies I cited (they compared homes with programmable thermostats to homes without programmable thermostats, instead of comparing homes before and after a non-programmable thermostat was swapped with a programmable thermostat). I'm encouraged to hear that thermostat-swapping programs can work, and I'm willing to consider removing programmable thermostats from my Useless list. Perhaps I'll put programmable thermostats on my Overrated list.
Michael Blasnik
Michael,
You should spend more time here....
Somebody needs to "correct" /challenge Martin every once in a while ;-)
High Performance homes
Programmable thermostats do not provide very significant improvements in High Performance homes.
One reason that setting back thermostats may not yield as great a savings as expected is because of the thermal mass of the house and contents....
the house and contents need to be re-heated or re-cooled.
thermostats....
Martin -- I'm glad to hear that you'll consider an upgrade to "over-rated". I can live with that, ;}
I'd just want to be sure that you don't confuse people into thinking that setting back temperatures doesn't save much energy. Just putting in a setback thermostat won't necessarily save energy -- but setting back the temperature will -- in most cases.
John Brooks makes the good point that temperature setback doesn't save much in homes with either high thermal mass or that are high efficiency (and especially both). If the indoor temperature doesn't drop much during the setback, not much can be saved.
thermostats....
If you reread the part on setback thermostats, it reads not that they don’t work and achieve energy savings; it is that many people don’t bother to use them in a setback cycle. If you look at the energy triangle that is comprised of the building envelope; building systems (setback thermostat) and occupant behavior, the statement indicates that the occupants (operator) are the issue. The setback thermostat will provide consistent scheduled setbacks to the occupant’s schedule and hence a smaller delta T (inside to outside), and the occupants will almost always awake or arrive to a home or building that has the right thermal comfort level.
Great List,
John
I'm not interested in confusing people either
Michael,
Like you, I'm not interested in confusing people. Here's what I wrote: "I’m happy to stipulate that anyone who actually programs and uses a programmable thermostat will save energy compared to someone who never performs thermostat setbacks. ... So here’s the bottom line: whether you have a simple Honeywell Round or a complicated electronic gizmo on your wall, it’s important to set back your thermostat."
I hope it's clear! Setbacks are good! Programmable thermostats are optional.
Programmable thermostats
The conversation is irrelevant - the IRC requires them.
And just as a side-bar, education is important. I rehabed some housing (section 8) for a local community action agency and installed among other energy saving devices, programmable thermostats. As part of my duties I went back six months later to see how every was working. I found to my dismay that often the thermostats were set at 80 and the residents controlled comfort by opening windows.
Useless products and the Code
Richard,
Oh, darn. I didn't know that I couldn't include code-mandated products on my Useless list. It must be I was evaluating them using the wrong criteria.
confusion...
I realize that you were clear in the text about why you listed thermostats (even if I disagree about the empirical evidence). My concern about confusion is that , in my experience, people see a list like this and then tell others -- "I read that setback thermostats are useless". The full nuanced message gets lost in the shuffle and confusion is spread -- even if unintentionally.
It sort of reminds me of the confusion I have recently seen about the recent FSEC study showing 11% cooling savings from painting exterior walls white. I have seen and heard several people take away that one piece of info even from the Home Energy article even though it isn't what the authors actually said -- the 11% savings were for a test hut where wall heat gain should be expected to be a larger fraction of the cooling load than in aa real house. People will grab a sound bite and miss the details.
energy scams and useless products
By far, the biggest scam lately is the huge advertising blitz for the claimed 50% savings by the Edenpure, Amish fireplace and similar space heaters.
Ah, yes — the Amish heater scam
The Amish heater scam certainly could have been included in the Useless Products list. This outfit is selling 1,500-watt electric heaters (widely available for $25 or $30) for $300 or more. The ironic twist to the story, of course, is that the real Amish don't use electricity. (Because of their gentle nature, they also don't sue scam artists who use the word "Amish" — a useful fact to know if you want to capitalize on their honorable reputation to dupe the gullible.)
If anyone cares to read more, here are some Web sites debunking the scam:
http://www.dailykos.com/storyonly/2008/12/3/102826/186/901/668287
http://k0lee.com/2008/12/amish-heat-surge-miracle-heater-scam/
http://www.consumeraffairs.com/news04/2009/02/amish_heaters.html
A Product is Useless if You Pay For It But Don't Get It
Here's a useless product for you, Martin. Based on your comment in a blog, "The best book on designing and installing a solar hot water system is Solar Hot Water Systems by Tom Lane. http://www.ecs-solar.com/lessons_learned.htm" I went to the website on September 15, paid 80$ by paypal to order the in-vivid-color version of the book, and have not received the book or heard anything at all from Mr. Lane or ecs-solar since. Everything I have ever ordered from websites would be here by now. Last week I emailed ecs-solar and I did not even get a response to the email--nothing. That's what I call extra useless.
SPOT ON!
Martin,
This my cause you to lose consciousness for a brief moment, but I AGREE WITH THE ENTIRE LIST! I know crazy right? We never agree on anything.
I recently spent a great deal of time explaining to a homeowner why purchasing a Power Save 1200 was not going to get her the savings a salesperson had promoted. Power vented attic fans are a true hazard, Vinyl is just gross no matter how you look at it, Fresh Air Intakes were a sad idea from conception.
You are spot on with your comment about thermostats. Setting them back is what is important, so an un-programmed thermostat is just as useless as a manual thermostat. Behavior is what has to change. I read a study a couple years back where the homes that had received new stats were not showing the savings the computer models had predicted and when they went back to try and determine why, they discovered that the thermostat had never been programmed and the homeowner didn't understand how to use it. They had continued to use the up and down buttons to manually adjust the temp for comfort.
Your list just goes to show that Education is, as most things, the least expensive and most impactfull solution.
Good job!
I'm not sure about the delay
Rick,
Well, you ordered the book 13 days ago. I'll admit that most book orders arrive sooner than that — but it's not as if it's been a month. (When I was young, every mail-order advertisement included this tag line: "Please allow 4 to 6 weeks for delivery.") I just called Energy Conservation Services, and was told that your book is on its way. I certainly hope you get the book soon. When you do, I hope you'll agree with me that the book is not useless.
I'll Bet the Lane Book is Not Useless at All, When Present
I have some time ago read the book Solar Water Heating, by Bob Ramlow and Benjamin Nusz, and I think it is well done, with some good details. However, there looks to be considerably more detail with the Lane work. Thanks, Martin, for your recommendation and the phone call. Now, all I need to do is sit back and figure out what the heck's wrong with me because, sorry, I had no business bringing you into it.
Another nomination...
I don't know if these are sold or promoted in the US, but here in Canada, we have a product called the whirly-bird attic ventilator. It is wind driven and does in fact draw air when it spins...but it has been shown that when the wind blows, there is enough of a pressure differential created to circulate air through the soffits without any help from a fan. Of course when it is calm, neither system works. Eventually, they wear out and blow right off the roof leaving a rather large hole that often goes unnoticed for some time...
I agree about whirlybirds
Garth,
You're right about whirly-birds. Of course, if you cut a hole in your roof near the ridge on a hot day, the stack effect will cause the hot air near the ridge to rush out the hole, while make-up air comes in at the soffits (assuming you have soffit vents). All fine and good, I suppose, but the effect has nothing to do with the twirly aluminum gadget that builders install over the hole. All that the aluminum device does is slow the air down as it leaves your attic.
If you want passive attic ventilation, install a conventional ridge vent. You don't need those aluminum spinners.
Programmable thermostats - is this an urban myth?
See my blog post at http://www.annmonroe.com/blog/2009/09/programmable-thermostats-stirring-up.html.
It's true that many programmable thermostats are used
Ann,
In your blog, you wrote, "Nowhere could I find an actual study - or an actual expert - with any hard information about the habits of programmable thermostat buyers. Which is, when you think about it, not surprising. After all, does it make sense that millions of people would pay good money for a gadget designed to save them even more money, and then not use it?"
While your statement may be literally true, we can certainly infer the behavior of programmable thermostat owners from the data collected by researchers.
Danny Parker of the Florida Solar Energy Center studied programmable thermostats in 1999-2000.
As reported by EDU, "Within our project, we had 19 homes with programmable thermostats that showed evidence of increased consumption and peak demand," Parker says. This is just the opposite of what the HERS rating and Energy Star Home Program now estimate. Parker says that he measured interior temperatures and space-cooling demand profiles at 15-minute intervals and found that people with manual thermostats were "much more likely to set up their thermostats than those with programmable models — just the opposite of conventional wisdom."
Craig Conner, a researcher at the Pacific Northwest National Laboratory, conducted his study in 2000. He wrote, “Our analysis of thermostat-related behavior was based on measured data from about 150 electrically heated, single-family homes located in the Pacific Northwest. … Interestingly, there was little difference on average between the setback behavior of people who own programmable thermostats and those who don’t. In both groups there are people who set their thermostats back almost every day and people who almost never do so. On average, both groups set their thermostats back about half the time. In other words, homeowners with programmable thermostats don’t set back any more often than owners of manual thermostats. Thus, we concur with researchers Scott Pigg and Monica Nevius at the Wisconsin Energy Center: the attitude of the occupants has everything to do with the way that thermostats are operated. The presence or absence of a programmable thermostat doesn’t have much effect on setback behavior.”
So, people who buy programmable thermostats do use them, and do perform setbacks -- but not any more or less than people with old-fashioned manual thermostats.
So would you include programmable t-stats in a retrofit program?
Michael, thanks for jumping into this thread. If you were designing a retrofit program, would you invest the $ in including programmable thermostats? Or would you do something else to the house with that money?
Are the Philadelphia gas and Gas Networks studies published somewhere for us to read in more detail (if we happen to be "more detail" kind of people)?
more thermostat info
Melissa- The CEE web site has lots of reports on thermostats. Just Google for "gas networks thermostats CEE" and you can find the gas networks report about halfway down the page. That study showed 75 ccf savings per thermostat.
The Philadelphia reports that I did are not published anywhere as far as I know, but I think I could share them with you directly if you email a request. The high savings were mostly achieved by one of the two contractors. In the 2005 and 2006 evaluations (each with about 2,000 homes of pre and post billing data) thermostat savings were estimated at 132 ccf and 141 ccf respectively for one contractor and 25 ccf and 19 ccf for the other contractor. Even the lower performing contractor's savings are quite cost-effective.
I think I should also mention that the Wisconsin study that is one of the key reports used to justify the "useless" tag actually showed that energy usage was about 2.5% lower in homes with the programmable thermostats. That difference would translate into maybe a 1-2 year payback on the cost of the measure. I think that's pretty good for something "useless" -- actually a quicker payback than retrofits like air sealing or insulation.
Personally, I find a programmable thermostat useful because it automatically sets the temperature to where I want it when I want it. I know I would sometimes forget to setback without it and I also like that it turns up the heat a little earlier in the morning (which does use a little more energy). I may not be savings a lot energy compared to what I could achieve with careful manual setbacks, but to me it's a very useful device that helps me save that energy with greater comfort and convenience. It certainly doesn't belong on a list of "useless" items.
Thank You
Martin,
Thank you for putting tyvek on top of your list. It is a tool in the fiberglass scam and nothing more. I would also like to take this oppertunity to introduce my "Amish bubble-wrap" which wil not only insulate your home but also works as solar panels, siding and floor joists :)
New data on "vent-free" space heaters
I've just read the results of an interesting indoor-air monitoring study conducted by a group of researchers, including William Rose. They installed extensive air monitoring equipment in 15 homes equipped with unvented gas space heaters. Among their findings: "Two of the 15 homes did have measured 8-hour average carbon monoxide levels that exceeded the threshold value of 9 ppm. In both of these cases the threshold value was exceeded during a time of extended continuous use of the appliance. Nitrogen dioxide was the gas that most frequently exceeded published guidelines. In 7 of 15 homes the Canadian threshold of 250 ppb was exceeded and in 11 of 15 homes the WHO threshold of 110 ppb was exceeded. If the three homes for which NO2 values were adjusted are excluded, the frequency changes to 6 of 12 homes exceeding the Canadian threshold and 10 of 12 exceeding the WHO threshold."
Rose's research report, "Indoor Combustion Product Concentrations Resulting from the Use of Unvented Gas Fireplaces," is available online.
One more attempt at explaining myself
Michael,
Thanks again for pointing out the potential usefulness of programmable thermostats.
You're right that I was setting myself up as a target by including programmable thermostats on a list headlined "Martin's Useless Products List." I tried to deflect a few arrows with my lead sentence, "Okay, these devices aren’t really useless ..." But I still received an earful from fans of the gadgets, including you.
Here's my takeaway point: gadgets will never be our salvation. Designing a gadget-filled home — even a home filled with the items from "Martin's Best Products List," which I haven't written yet — won't make anyone any greener. Ultimately, a green lifestyle is about behavior. This nugget of truth has been clearly highlighted by the programmable thermostat studies I cited. While there may be some benefit to the devices, ultimately human behavior matters more than the gadget on the wall.
If you are a setback type of person, you are likely to set back the thermostat wherever you live, regardless of the thermostat type. If you're not a setback-type person, you won't set back your thermostat, even if your thermostat speaks 12 languages and is connected to the Internet.
I think it's an important, humbling truth. How we behave matters more than what we buy.
LED lamps
Martin,
I'm interested where you got your data on the LED lamps. Are there certain manufacturers that can be trusted to not exagerate their lumens per watt claims?
LED data
Dave,
The LED data came from an excellent DOE program, the Caliper program, which is part of the DOE's Solid-State Lighting Program. More information can be found here:
http://www1.eere.energy.gov/buildings/ssl/caliper.html
The Caliper researchers have performed several rounds of testing. While editor of EDU, I was particularly interested in the results of Round 4 testing, which highlighted exaggerations made by Cyberlux (manufacturer of Aeon LED lights) and Permlight Products (manufacturer of the Enbryten LED light). Permlight has since entered into a partnership with Progress Lighting.
Cyberlux advertised that the Aeon Pro produced 55 lumens per watt. The DOE's test showed the product actually produced 16.1 lumens per watt.
Permlight advertised that its 15-watt Enbryten dowlight produced 40 lumens per watt. According to DOE testing, it only produced 12.8 lumens per watt.
In the Round 4 testing report, the accuracy of manufacturers' claims was summarized: "In earlier rounds of testing, discrepancies were observed between the light outputs and efficacies published by manufacturers and their CALiPER-tested performance. In Round 4 of CALiPER testing, these discrepancies continue to abound. Fifteen SSL products were included in this round; the remaining five products, tested for benchmarking purposes, use fluorescent or halogen sources. Out of the 15 SSL products, the accuracy of manufacturer performance reporting can be summarized as follows:
• Accurate performance reporting (1): One manufacturer provided accurate performance information for its luminaire (CALiPER 07-43—publishing luminaire output and efficacy values within 10% of the CALiPER measured results).
• No performance reporting (4): For four products, no manufacturer-published information was found regarding output or efficacy.
• Understated performance reporting (1): For one product, the manufacturer literature understated the output and efficacy of its SSL product by 50%.
• Overstated performance reporting (9): For the other nine SSL products, information published by manufacturers regarding product output and/or efficacy overstated performance (by factors ranging from 30-600%)."
unvented
Martin,
As I mentioned to you in an email, we like to present our research on unvented heaters where the discussion begins with questions about these devices, and we shy away from injecting our research findings into discussions where the question and answer period appears to be over. Of course, in a forum like this, taking a strong advocacy position as you and Alex Wilson do, shouldn't preclude open-minded review of research results. We did not take an advocacy position regarding these appliances. Jeff Gordon, a Co-PI, explains it this way:
"To take an advocacy position requires us to make a judgment on the health-based thresholds. The thresholds exist, and they were prepared by qualified people, but research on health impacts of low level concentrations are not conclusive, and naturally there is some guesswork involved in establishing thresholds (Health Canada 250 ppb NO2, WHO 110 ppb NO2, clearly each group is taking a stab at it). We are not health professionals, and thus are not qualified to make a judgment on the competency, quality, and conclusions of health-based research, or on the subsequent derived thresholds. We are qualified to measure and document combustion gas concentrations and present them in the context of the thresholds, which we did well. "
I sent you some links for our research. One of the links, which you cite above, was for a preliminary report (15 homes) and the rest were for the full report (30 homes). I encourage readers to go to the full report here http://netfiles.uiuc.edu/pwf/shared . (Martin: feel free to HTML edit for better linking.)
behavior - most over-rated excuse ;}
Martin-
I have to say that I completely disagree with your apparent claim that we need to change behavior to save energy. I don't care how "green" your behavior is - if you have a 1970's refrigerator it will use much more energy than a new refrigerator -- even if you never open the door! In general, it takes fairly extreme lifestyle choices to compensate for inefficient homes and appliances. I think technical improvements are much more likely to have an impact on our energy usage than encouraging green lifestyles -- although we should do both.
I think it's a common scapegoat to blame occupants for why things don't save energy or why building simulation models are so bad. Sure, in extreme cases behavior can have a huge impact, but in the vast majority of cases, behaviors are in a fairly narrow range based on people seeking comfort, services, and convenience. Better gadgets can allow people to dramatically reduce the energy needed to maintain a comparable lifestyle.
This discussion won't be settled here
Michael,
I'm thinking about the questions raised by the Jevons Paradox — the idea that efficiency improvements alone are unlikely to lead to a reduction in energy consumption. As I wrote in that previous blog, "Communities that have a low environmental impact and live in harmony with nature are not particularly efficient. Our planet’s future is being threatened not by traditional rural communities with old-fashioned methods of livelihood, but rather by industrial economies where efficiencies are highest."
When one considers the entire range of human lifestyles — from rural African villagers to suburban Americans — it's hard to conclude that gadgets will save us. But I'm all in favor of using tools that use as little energy as possible.
Jevon's Paradox
Jevon's paradox is widely misinterpreted. It is true that when you make a dramatic improvement in the efficiency and usefulness of something, you may actually use even more of it -- like Jevon found with coal after the invention of the steam engine. But these relationships aren't boundless. If my car gets double the mpg it doesn't make me want to drive twice as far. The key issues (speaking as an economist) are elasticities -- price elasticity and income elasticity . It is easy to get confused about the two and think that just because overall energy usage has gone up that therefore efficiency hasn't helped. That belief is just nonsense.
If you think that comparing our energy use to that of primitive societies is going to help save energy by convincing first world people to give up things like lighting, refrigeration, space conditioning, computers, etc... -- all I can say is good luck with that. But back here in the real world, most people want the benefits of modern society and it will require lots of great gadgets and efficient use of resources to provide those benefits to as many people as possible.
Behavior change for efficiency
Michael Blasnik: To increase the efficiency of this forum, you should not write, since you suffer from confusion an illogic.
CO levels
Great article and discussion. Do you know of a national standard or anything that shows the ppm of CO that is actually harmful. BPI uses 35 but most of the CO detectors that are sold do not go off until they read 60 ppm for a period of 45 minutes (or something close to that, numbers may be off slightly)
I have told many people that vent free fireplaces are a no no and harmful. Am typically challenged by how long they have had it without any problems and "things the salesman told them" Very low levels of CO - if the CO level gets too high, the flame will not burn since there will not be enough oxygen and that the moisture released is not bad since many people like to humidify their homes during the winter anyway. Building science and common sense tell us they are not safe but would like some documentation to back up our theory.
Debating health issues
Danny,
As William Rose pointed out, building energy specialists need to be aware of their professional limitations. A question about the medical effects of different CO or CO2 levels is best conducted on a medical forum, not a building science forum.
Rose's research did find that many houses with unvented gas space heaters had elevated levels of nitrogen dioxide: "Nitrogen dioxide was the gas that most frequently exceeded published guidelines. In 7 of 15 homes the Canadian threshold of 250 ppb was exceeded and in 11 of 15 homes the WHO threshold of 110 ppb was exceeded."
More on LED scofflaws
After I posted this ten-worst list, the New York Times blog on green energy issues published a story about LED scofflaws with exaggerated lumens-per-watt claims. Read the article here:
http://greeninc.blogs.nytimes.com/2009/10/01/led-scofflaws-abuse-lighting-label/
More on behavior and conservation
For those who have been following the debate on how human behavior affects energy use levels, here's an interesting article describing how providing information on neighbors' energy use can lead to lower levels of energy consumption:
http://features.csmonitor.com/innovation/2009/09/30/energy-use-falls-when-neighbors-compete/
LED Light Output
I would not argue with the statement that CFLs produce more total lumens/watt. However, the majority of LED fixtures being sold are for task lighting. I would argue that for task lighting, LEDs produce much more usable lumens/watt than CFLs or any fluorescent lamp for that matter. Consider this example: a CFL bedside lamp uses 18 watts and is used for reading. It illuminates the page of a book well, but also lights up the ceiling and walls of the room. If this lamp is replaced with a 20 LED reading lamp that uses less than 2 watts (including the power inverter), you will get as good or better lighting on the page of the book but with 1/10 the power. Making a blanket statement that CFLs are more efficient than LEDs is misleading and should be qualified.
Insulated Vinyl Siding
Mr. Holladay,
Have appreciated learning from you through EDU over the years and so was disappointed to learn that insulated vinyl siding made your list. While R-3 or R-4 may be considered modest improvements compared to deep energy retrofits, they do provide a measureable benefit and are always better than new siding with no exterior insulation at all. In any case, the higher the R-value the better.
On the rainscreen issue, why is it assumed that insulated vinyl siding limits drainage or reduces the wall’s drying potential? Is this based on commonly accepted theory alone or on some direct observation? There is a growing body of evidence from more than 10 years of exceptional field performance as well as 3rd-party field inspections, field experiments, and lab studies that documents the ability of insulated vinyl siding to keep wall systems dry.
Limiting drying potential
Filling the corrugated space behind vinyl siding with form-fitting flat-backed foam limits a wall's ability to dry to the exterior in two ways:
1. The ventilated air space between the vinyl siding has been largely removed. Countless wall drying studies show that a ventilated air space between siding and sheathing improves wall drying.
2. The addition of the EPS layer reduces the vapor permeance of the siding layer.
Expect this list to be expanded!
Consumers really need such a list to eliminate their redundant expenditure on uesless devices.
I hope this list could be expanded. For instance, PV panels may be lower cost-efficient than solar thermal collector in some areas. Some techniques in fact may consume more energy during the whole life cycle.
In addition, there could be a list for time-honored, high energy-efficient strategies and devices.
Thanks for your inspiring work!
Insulated Vinyl Siding
Mr. Holladay,
There is no question that the corrugated space behind standard vinyl siding promotes wall drying. It does not necessarily follow that filling in that space with insulation creates an unacceptable restriction to wall drying.
The countless studies you refer to probably evaluated a variety of standard cladding materials and systems. It is unlikely they studied insulated vinyl siding specifically. If this is the case, I would appreciate your consideration of a new study that does just that.
Insulated vinyl siding has been included in a year-long wall moisture study along with other claddings at the NAHB Research Center’s outdoor testing facility. The study monitors the moisture levels in the wall cavities, studs, and structural sheathing on both north-facing and south-facing walls. Bulk water was also “injected” into the wall cavity to supplement what could be learned from the study.
Eleven months into the study, the preliminary results clearly document that insulated vinyl siding performs as well as, or better than, all other claddings in the study.
Please let me know if you’d like to review the most recent summary of this study along with related information.
Sure, I'm interested
Tim,
I'm always interested in reading research reports. Please send me a copy of the report on the study you mentioned: martin [at] greenbuildingadvisor [dot] com
Thanks!
What about the wind washing
What about the wind washing effects on insulated vinyl siding? Wouldn't the air flowing behind the siding/foam short circuit the insulation?
I doubt it
Garth,
I doubt it. I can't imagine that the airflow behind the product is significant. But you have a point: ideally, insulation is enclosed on all sides by air barriers.
R-value testing "as installed"
Hello, Mr. Sproule
Air circulation (wind-washing) is being taken into consideration. Unlike windows, doors, and insulated garage doors which seal off the entire assembly during ASTM C 1363 "Guarded Hot Box" testing and thereby eliminate the effects of air circulation that exists in the real world, insulated vinyl siding is tested "as installed" to account for the affects of air circulation.
Three rounds of this testing have been completed and a fourth is underway. Based upon the results of this testing, sample prep details will be established and built in to the ASTM standard for Insulated Siding (currently under development).
What we have learned so far is that the minimal air circulation that does exist has a minor impact on the final R-value, but does not eliminate it.
Thanks for your question!
About Tim Holt's data
For those who are curious about Tim Holt's reference to "a year-long wall moisture study [of the performance of insulated vinyl siding] ... at the NAHB Research Center’s outdoor testing facility," here's what I have learned:
1. Tim Holt is an employee of Progressive Foam Technologies, the company that manufactures the corrugated polystyrene insulation used by vinyl siding manufacturers to make insulated vinyl siding.
2. The study he mentioned has not been completed, so a full report on the study's findings are not yet available.
3. Mr. Holt shared a letter to Progressive Foam Technologies providing some preliminary data; however, in the absence of a full research report, it's hard to evaluate whether the limited data shared in the letter represent typical or atypical results.
4. The line graphs of various moisture content levels of studs and OSB in the test walls showed that for 3 out of 4 monitoring points, the moisture levels in walls covered with insulated vinyl siding were lower than the moisture levels in walls covered with conventional vinyl siding. In 1 of 4 monitoring points, the wall with insulated vinyl siding had a higher moisture content than the wall with regular vinyl siding. In this last instance, the OSB behind the insulated vinyl siding had a moisture content that varied over a 6-month period in a range from 12% to 14%.
I look forward to assessing the study when the study has been completed and full data are made public.
Air Vents
Hi, Martin--
My first encounter with make-up air vents was during the Super Good Cents home program in the 1980s. The program was sponsored by the Bonneville Power Administration and our region's electric utilities (Washington, Oregon, Idaho and Montana). Early on, BPA's environmental assessment staff raised concerns about the potential for accumulating indoor pollutants in houses that had been air tightened at the direction of the program, especially radon. The program administrators had made a strategic decision not to require builders to pressure test their building envelopes, rather, builders followed a prescriptive set of air sealing measures. This meant that while overall house tightness generally fell on a nice bell-shaped curve, it was possible that an individual house might be very tight (simple envelope, electric heat, no combustion appliances, careful air sealing). The possiblity of a tight house located in a high radon area (in my opinion) caused the program administrators to include mechanical ventilation as a health and safety measure. Remember, this is long before ASHRAE 62-2. Initially, the program mandated air-to-air heat exchangers (AAHX, today known as HRVs). Builders received a substantial financial incentive for installing these. One popular lower-cost model designed around a heat wheel consistently froze up in cold climate winters, and gave AAHX a reputation for low quality and durability, despite the fact that Canadian AAHX were of very good quality. AAHX were also (in my opinion) not well understood by occupants, who frequently shut them off. After the issues with AAHX, the SGC program then turned to a mechanical ventilation alternative based on exhaust fans, timer controls and make-up air vents.
Several thousand houses and manufactured homes have been built in the SGC energy efficient home program with air inlets located within window frames or through-the-wall inlets. Since the houses have not been individually measured for tightness, I concur that it is correct to say that in houses that are not tight, air vents may be superfluous and under some circumstances operate in reverse, that is, the stack effect and/or wind pressure could create positive pressure that drove air out through the air vents, turning them into air "outlets".
In cold climates, air inlets are frequently perceived as a nuisance by occupants because they admit cold outdoor air in winter. Window vents in particular may be defeated by occupants closing them off. Air inlets can be installed in closets or unoccupied rooms (like a pantry) to avoid or minimize this perception, but the least cost and most popular option has been the window air vent.
Nevertheless, I would still argue for using air vents in one circumstance: in the case of a house that actually is tight (in the range, say, of 2 - 7 ACH at 50 Pa) and uses exhaust fans for ventilation. If such a house is closed up, so that exhaust fans do create negative pressure on a tight envelope, there should be adequate make-up air from outdoors (not the garage, say).
In addition, the Washington State Indoor Air Quality code requires air vents as part of "source specific" or exhaust fan type systems:
303.4.1.5 Outdoor Air Inlets: Outdoor air shall be distributed to each habitable room by individual outdoor air inlets. Where outdoor air supplies are separated from exhaust points by doors, provisions shall be made to ensure air flow by installation of distribution ducts, undercutting doors, installation of grilles, transoms, or similar means where permitted by the International Building Code. Doors shall be undercut to a minimum of one-half inch above the surface of the finish floor covering.
Hmm -- how much air leakage area does a house have?
Mike,
You call homes with 2 to 7 ACH @ 50 pa "tight." Using your definition of tight, let's consider a 2,550 square foot house with 2.3 ACH @ 50 pa. The house has an envelope surface area of 6,732 square feet. The Equivalent Leakage Area of the infiltration and exfiltration leaks is 128 square inches.
So this "tight" house already has envelope leaks equivalent to 32 fresh air vents (each of which provides 4 square inches of ventilation). So are 3 or 4 of these devices going to make much of a difference? No -- they are just going to irritate the occupants.
In other words, even your theoretically "tight" house already has plenty of random leaks — more than enough to provide makeup air for the exhaust fans.
Air Vents
I've read the comments on air vents carefully and with great interest. I am looking to build a house with a tight envelope. Although I won't have any vented gas appliances, I will have fireplaces with chimneys. I will also have mandated and necessary kitchen exhaust.
The concern I have is that without "planned" air infiltration to handle make-up air needs for exhaust then the air is forced to enter through envelope leaks. Such spaces are prone to air quality issues and will often suffer from humidity induced issues like mold and mildew. Furthermore such spaces often have greater airflow resistance than ventilation flues. At any rate, whether the make up air comes from flues or envelope leaks it creates hazardous IAQ issues and if it results in moisture in confined gaps in the envelope it can also cause long-term structural issues in high humidity environments.
This is where I have come to believe there is some value in planned air infiltration for makeup air. I don't want moist air entering uncontrolled through the cracks in my envelope.
Instead I want to target my makeup air as close to the exhaust source as is practical. And if possible I want t at least partially precondition sch makeup air.
But as I understand it an Erv/HRV can't be used to supply makeup air for a major exhaust source like a kitchen fan. So... Doesn't someone make a fresh mke-up air pipe with a back flow prevention valve? That would just seem logical to me. You'd get safer healthier makeup air than can come from dusty cracks in the envelope. You wouldn't risk negative pressure back flowing your flues. And she the exhausts aren't actively sucking and causing negative pressure, you can maintain a healthy positive pressure in the house while the back flow prevention valve on the fresh air intake prevents unnecessary air/energy losses
Regardless, with or without such a back flow prevention valve, I think it would be better to lose some conditioned air out auc a fresh air pipe, than to uncontrollably suck air through poor air quality cracks in the envelope.
I'm know expert here. Just a homeowner designing my future house. What am I missing?
P.S. I'm learning a lot from everyone here. THANKS!
Conditioned makeup air units
Grant,
Shelter Supply sells make-up air appliances that provide heated makeup air. These devices can be interlocked with a kitchen exhaust fan so that they come on automatically when necessary:
http://www.sheltersupply.com/corporate/default.asp?cwpID=16
My own two cents:
1. Get the smallest kitchen range hood you can get away with — 200 cfm is much better than 600 or 800 cfm.
2. Kitchen range hoods are usually incompatible with traditional wood-burning fireplaces.
3. Conditioned makeup air is an expensive solution to this problem.
More on programmable thermostats
Here's another paper that discusses programmable thermostats: “Programmable Thermostats as Means of Generating Energy Savings: Some Pros and Cons,” by André Plourde, March 2003.
Plourde wrote, “Early work that examined the effectiveness of programmable thermostats, based on simulation models, and focusing almost entirely on oil- and gas-fired space conditioning in a residential setting, concluded that these devices had a significant potential to reduce energy use. A general rule of thumb that derived from this analysis was that for each degree Fahrenheit of nighttime temperature setback implemented for eight hours each day, energy savings of the order of 1% would be achieved. However, more recent results, including survey evidence, suggest that for various reasons the extent of any energy savings resulting from programmable thermostats in a residential context is much less than this amount. … More recently, questions have been raised about the potential for programmable thermostats to deliver any additional energy savings, even in situations where natural gas is the energy source used for space-heating purposes. Survey evidence suggests that the net changes in temperature-setback behavior resulting from the ownership of a programmable thermostat are much smaller than assumed in the earlier, simulation-based studies.”
Barn or PassivHaus, that is the question.
I've been reluctant to jump into the programmable thermostat wars but what the hell, here's my 2 cents:
Martin has clearly stated two principles: 1) setbacks are good; 2) you don't need a programmable 'stat to achieve them. On principle 1), yes - but. Setbacks are most useful with a building which is not tight and well-insulated. Energy savings from setbacks depend on the reduction in Delta-T as the house cools, resulting in slower and slower energy transfer. The leakier the house, the faster the cooling, the greater the savings from the setback. Optimal savings will result when the house can cool right down to ambient outside temperature for an appreciable period before the heating kicks back in. This describes, say, a barn or a tent. At the other extreme a house insulated to PassivHaus standards will barely cool in the setback period and savings will be unnoticeable.
On item 2) - yes, the programmable 'stat is of course useless if not deployed, and will be unnecessary in a less than perfectly insulated home if the occupants can be depended on to set back the thermostat manually, also in an extremely tight well-insulated home where setbacks are simply without value, as in the PassivHaus example.
However, a programmable thermostat can be very useful indeed in a less than perfect house with less than perfect occupants. Mine, for example. I installed an inexpensive programmable 'stat at the very beginning of a slow incremental process of much more costly thermal envelope improvements. It paid for itself (all of $35) in a matter of months, not years. It still has value today, though not at the same level of energy savings because since the other improvements my total energy use has dropped to a third of its previous level. I still find it useful because my home though much improved is no Passivhaus, and it ensures that a temporary over-ride, because of an illness perhaps, does not become the new normal. It does this without my having to think about it, it has already paid for itself many times over, and if it broke I would replace it with a similar model tomorrow. I don't know any other energy-saving option that costs so little that it make senses even for a renter to install.
Makeup air
Martin offers good sense as usual in his comment on kitchen exhaust fans. The craze for 'professional quality' cooking equipment has brought with it restaurant scale hoods pumping huge exhaust volumes. A local example reported to me was of such a hood installed in an overscaled trophy home without the makeup air supply that commercial kitchens always include. When that sucker was first cranked up the house instantly filled with smoke from the baronial fireplace in the great room.
This is not an argument for providing makeup air supply to a residential kitchen, it's an argument for small exhaust vents minimally deployed. Cook the stinky stuff outside on the grill, why don't you!
Foam-backed vinyl siding question
Martin, great list. We are currently considering "flat back" EPS-backed vinyl siding over XPS 1" sheathing (we're being careful to ensure that XPS forms a continuous insulation layer using Building Sci. Corp guidelines). BUT (1) we *cannot* get cultured stone manufacturers or installers to commit to the installation of their products over more than 1" of XPS - even with brickledge and ties (we wanted to have 2" XPS originally) and (2) we see that long lengths of vinyl siding "wave" noticably over time despite quality installation. So EPS-backed siding solves two problems: rigidity plus just a bit more external insulation. Over XPS, I don't see any "drying issues." Please comment? And I welcome your thoughts on creative alternatives. Martin, great writing and great follow-up answers to your readers. You really set a fine standard. Thanks in advance!
Insulated vinyl siding over foam sheathing
L Rozman,
I don't think you'll have any problems with your installation, as long as:
1. Your foam sheathing is properly detailed as a WRB (water-resistant barrier), and
2. Your wall assembly is allowed to dry to the interior (no interior polyethyelene).
Good luck.
Anonymous postings
It is easy to be bold when hiding behind anonymous. If you are that sure of your opinions and conclusions, come out of hiding and share with the rest of us.
programmable t-stats
Maybe programmable thermostats should come with a default program set to 70 (daytime) and 65 (overnight) - my guess is that both numbers are slightly lower than the average homeowner chooses, but within tolerances. (For what it's worth, mine is set to 67 and 60 in a daily 4-period rotation.) Then, it should be easier to tweak these pre-sets than to turn the program off - for instance, an up-down button should primarily allow homeowners to change the programming for the current period - thus, if someone is cold at 70, they can bump it up to 71, but this would have no effect on the overnight 65 setting. Nor would it turn the program off, which would require more difficult tweaking.
I've had tenants - smart tenants, a PhD and an attorney - who don't use the programmable thermostat I provided. At this point, I don't feel comfortable going in and programming it for them. (I pay for heat - because the building is well insulated and I feel this is a lower cost to me than ther perception of savings on the part of tenants.) At any rate, I know that when the next tenants move in, they'll move in to a pre-programmed thermostat. If they want to change the program, they'll need to figure out how. My guess is they won't.
t-stats in Florida
The other thing is that the primary data being cited against them (once Michael showed that the Wisconsin study actually did find energy savings for them) is one from Florida.
I think this points to the major difference between air conditioning and heating. Conditioned air can be brought to a temperature that sometimes feels hotter than air of the same temperature brought through the windows by a breeze. Programmed thermostats in a hot climate encourage people to leave the windows shut and let the thermostat handle everything, rather than turning on the air only when it's actually hot and still enough to require it. In a climate where the primary usage of residential indoor HVAC is for heating, the terms are completely different.
So I don't think a Florida study is relevant to much of the country. The take-away may be "programmable thermostats are a bad idea in Florida/Phoenix/SoCal climates".
LED lights
The comment on LED lights is a bit misleading in my opinion, without revealing that there are very good high quality general LED lights available now. They are not cheap but as with almost any new technology it will come down in price over time. I remember having to pay $20-$40 for CFL's 15+ years ago. I picked up several Philips EduraLED/AmbientLED which easily appeared to me to be brighter to a 60 watt incandescent I compared it to in the same lighting fixtures. Using a watt meter they also used less (12 watts) then several "60 watt" CFL I compared it with. If it is indeed equivalent to the light output of a 60 watt incandescent as it does appear to be then that would mean it is over 60 lumens/watt.
Two other important attributes of LED bulbs is their lack of any mercury (which all CFL's have) and their ability to be unaffected by low temperatures.
Response to David Bainbridge
David,
My comments were directed specifically at "inexpensive LED lamps."
Foil Faced Bubble Wrap
I agree with your thoughts on energy wasters and the comment that the Amish $300 heater is right on. I have had to convince friends that a resistance electric heater is a resistance electric heater no matter how you package it.
Question about the bubble wrap. Are you referring to a house wall wrap product or the stuff that is applied to the underside of the attic rafters to supposedly reduce your heating and cooling bills by 25%. Is there really any merit to this application?
Glenn Ogden
Response to Glenn Ogden
Bubble-wrap products always have a low R-value -- in the range of R-1 or R-2. I wouldn't install one anywhere.
An Alternative Use for Foil-Faced Bubble Wrap
Aware of your long-standing contempt for foil-faced bubble wrap, I may have found an alternative use for this product, which disregards its claimed insulation value and takes advantage of its tensile strength. Behold.
The problem: summertime temperatures in our attic routinely exceed 130 degrees while outside temperatures exceed only 110 degrees. HVAC ductwork is housed in this attic. When this home was built in 1978 insulation consisted of six-inch batts of fiberglass between half (go figure) the joist bays in the garage and all the bays over the living space as well as on the vertical walls around the cathedral ceiling of our living room. The garage and living space are connected. Two-inch batts of insulation were wrapped around the ductwork.
Two energy audits over the last two years reported that we had the equivalent of an open window in our home twelve months a year. Two possible sources were identified: the absence of insulation over the attic access panel and a major leak in our HVAC ductwork. In order to solve those two problems, I needed to create a safe working environment and build a path to the HVAC plenum where I could seal the suspected leak.
Complicating factors:
a. A 44-inch clearance between the top of the attic joists and the highest point on the bottom of the rafters.
b. Thirty-three years of a heavy accumulation of dust atop the attic insulation.
c. Attic access through a narrow front entry hallway; hence, the need to build an access through the garage ceiling.
d. Only pathway to the HVAC was over the attic access with was covered by a thin piece of aluminum and nothing else; hence, need to build a solid attic access that was not only well insulated but sufficiently strong to bear extensive traffic.
Thus began my long attic odyssey.
After considerable research I resolved that I needed to create a conditioned space with the following characteristics for the rafters:
a. 1 x 2-in furring strips (aka sisters) glued and screwed to the rafters directly under roof sheathing
b. foam attic ventilation channels between sisters
c. radiant barrier over ventilation channels and stapled to sisters
d. rigid polyisocyanurate foam insulation attached to the underside of the rafters.
This extensive application of materials to the rafters required a strong and safe foundation from which to work. Batts of R-19 fiberglass insulation wouldn't cut it. I attempted to use an arrangement of plywood sheets resting on top of the joists but that proved unsafe and practically impossible because of the configuration of the trusses. One false move and I knew I'd end up in the room below.
Rigid expanded polystyrene foam seemed like a natural alternative but early experimentation with my full body weight resting on top of the eps resting on top of ceiling gypsum board resulted in some unnerving cracking sounds in the gypsum board.
So I needed an alternate plan Q. I needed something to put between the joists that could bear my weight. I walked the aisles of several hardware stores in town for days. I searched the internet. I talked to friends and relatives. No one had a ready-made solution.
Standing in the insulation aisle at my nearby hardware store I started to think about the possibilities of foil-faced bubble wrap. What if I could securely attach this stuff to the sides of the joists? Would it safely bear my weight if I combined it with eps foam? Would GBA forgive me? Basically, the idea was the equivalent of a vehicle with low-ground pressure tires traveling over ice. Displace as much weight as possible over as broad an area as possible.
After some more experimentation this is what I derived:
a. 1 x 2-in sisters glued and screwed to the joists directly above the ceiling gypsum board
b. foil-faced bubble wrap stapled every three to four inches to the sisters
c. One-and-one-half-inch eps fitting snugly atop the foil-faced bubble wrap between the sisters.
d. Two-inch eps, cut one-and one-quarter inches narrower than the space between the joists, resting atop all of the above.
e. Expanding gap-filler foam injected into the spaces between the joists and the two-inch eps.
f. A 3/4-in x 24-in piece of plywood cut one-half-inch narrower than the width of the space between the joists; aka a "surfboard."
With this configuration, I've been able to move through this very restricted workspace safely and confidently. I confess my bank account has been severely traumatized by the experience and my wife no longer calls me by my given name. Thankfully, she's not using profanities but she has gone to calling me "Atticus." In her mind she may be spelling that with two s's at the end.
You may be interested to know that I've contacted the manufacturer of a major brand of foil-faced bubble wrap and asked them whether, under the conditions described above, their product retains any insulation value whatever. I have yet to get a response. No doubt, they've thrown the full resources of their research and development department behind answering this important question.
About half-way through this project I started taking photos of my effort. I didn't dare take my camera into the attic before then because of the treacherous conditions and the severe dust load. If you're interested, here's a link to my photo gallery: http://gallery.me.com/mawsonii#100903.
Foil Faced Bubble Wrap
Martin,
I understand that bubble wrap has a low R value and is a poor choice to provide insulation value. As I understand, the purpose of using it on the bottom side of the roof rafters is to provide a convection channel to remove radiant heat coming through the roof surface flowing between the soffet and ridge vents and as a radiant barrier to reflect heat away from the attic space. Is it as effective as the supplier advertises? Does it affect TV reception if one has antennas located in the attic? For my learning and future reference, what other uses were you referring to for use of this product?
For reference, some things I have done to improve the energy efficiency of our home that may be of interest to others:
1) I built a 4" think R 22 foam door over our attic fold down stair opening (hinged, metal frame, door weather seals, spring/cable/pulley system to counter balance it) and the same over our whole house vent fan. Beats having big holes through our attic insulation envelope.
2) Added a 2x4 framework over the ceiling joists at 90* so I could place two layers of R19 FG insulation to minimize the thermal break of wood through the insulation blanket and allowing me to deck the attic for storage.
3) Coupled with #2 above, most of our AC duct work is now sandwiched between the two layers of insulation, the little remaining exposed flex duct has a double layer of insulation and the air handler is encased with 2" foam board insulation.
Glenn Ogden
Response to Glenn Ogden
Glenn,
Ventilating an attic is not a dependable way to lower attic temperatures. A radiant barrier is more effective at lowering attic temperatures than ventilation, but you don't need bubble-wrap if you just want a radiant barrier.
Any investments in a radiant barrier or ventilation improvements will yield far less in energy savings that investments in air sealing and attic floor insulation.
Note from energy conscious Floridian on Programmable Thermostats
As a FL resident with a programmable thermostat, I must admit that I don't use its full programmable functionality. My reason is not that it is complicated but because of an overwhelming design flaw of the device itself (especially to use here in FL). That design flaw is that there is no battery backup option included in the device. As a result, every time there is a power fluctuation (which happens a lot here due to storms and bad equipment), the entire device is reset and all programming to the device is lost. This means that I am forced to spend the time reprogramming the device at least once a month and often more than that depending on storms or rolling brown outs. With that being the case, I gave up on using the device as an energy saving tool as it became a time wasting burden. Now, I've had it for quite a few years so they may have realized their design mistake and begun to produce ones that can secure the programming with battery power but without this critical feature, people without reliable and constant power are not going to bother setting up a program. In fact, I'm still annoyed that I wasted more than $50+ on this device when I first purchased it only to find it functionally unusable and flawed in actual use. Thanks for finally letting me vent it out. ;)
Thanks, Chris
Chris,
Thanks for an important reminder. Designers and engineers often forget the most basic usability features.
one more time . . . on thermostats.
Well, after reading this blog I'm not as sanguine about the value of programmable thermostats. However, a couple-or-three quick points:
Most all progammables I've installed came pre-programmed with set-backs to 62 or 65 F at night (around 10 pm to around 6 am) and then back up to 70 for the day, so the client had to deliberately RE-programe them if they wanted to use as a simple NON programmable. That pretty much takes care of the "people don't program them" problem.
Secondly: I always use the least expensive programmable (at present that's around $30) so payback is ASAP.
Lastly: Surely they must save SOME energy simply because even the most diligent of the "manual set-back" folks will sometimes forget to turn them down at night or when they're at work, but how many folks forget to turn them up? Hardly any, since the chilly temps act as a "reminder" . . .
Having said that, great discussion, and I'll for sure think twice now before recommending, and most definitely stay away from the more expensive models.
Guessing what people do is a losing proposition
I enjoyed the list and the discussion. Almost all of the data presented in GBA's pages, and other places, shows that when we actually measure people's behavior, we find it is usually quite different from what they report, or from what we/experts expected. Hence, I am skeptical of any conclusions on energy usage based on anything other than measuring energy usage.
Relating to the discussion here on the use of programmable thermostats, I am confused by the frequent statements, that people who seldom remember to set back their thermostats will do so equally rarely, whether they have a manual or a programmable. If a user of a programmable thermostat remembers once per season to program it, doesn't that imply continued setback every night for the remainder of the season, regardless of the poor memory of the user? Further, most programmable thermostats will retain their settings between settings, and many come from the factory with a setback program as the default.
These three factors would lead to significantly different results between the owners of manual and programmable thermostats, across the class of people that have been variously described as the forgetful people, unmotivated people, the people uninterested in energy, conservation, or thermostats. Yet Martin and others posting here have said that most people in a given motivational class will end up with roughly the same number of nights with temperature setback, regardless of the thermostat technology involved. Can you explain?
Space Heaters
I received an infrared heater for a gift last year. I seen that you guys were talking about how the amish heaters were worthless. Im almost afraid to ask but what are you all opinion on the infrared heaters that they sell at Lowes. This is not the amish one; its called the iheater. I did the math for the ratings and it says that it would cost $3.60 a day to run the thing for 24 hours straight. I run it after work and most of the night so it is probably only costing me about $2 a day to run. This isn't in addition to heat pump as the house is only 1000sqft so it doesn't run when the infrared is on. It keeps the living and bedroom quite cozy and $2 a day doesn't sound bad to be comfortable in NC winters. Am I crazy for heating with this instead of my heat pump???
Response to Stephen Longworth
Stephen,
You're certainly right that programmable thermostats have the potential to save energy. If purchased by a motivated buyer, they definitely make sense.
If they are installed willy-nilly by well-meaning do-gooders as part of a neighborhood-wide energy-efficiency program, however -- something that utilities have been known to do -- the energy savings are far from clear.
You wrote, "Most all progammables I've installed came pre-programmed with set-backs to 62 or 65 F at night (around 10 pm to around 6 am) and then back up to 70 for the day, so the client had to deliberately RE-programe them if they wanted to use as a simple NON programmable. That pretty much takes care of the 'people don't program them' problem."
Here's the problem: the first time that the homeowners feel chilly when they are watching TV at 11 pm, they will push every button on the thermostat until they find the "manual override" feature. At that point, the energy savings vanish. Most homeowners never figure out how to reprogram them to meet their schedule.
Response to Derek Roff
Derek,
Bravo -- I applaud your skepticism. Like you, "I am skeptical of any conclusions on energy usage based on anything other than measuring energy usage."
At least two field studies of programmable thermostats have measured energy use in homes with programmable thermostats and compared that to energy use in homes without programmable thermostats. One of these was conducted by Danny Parker (a researcher at the Florida Solar Energy Center), and the other by Craig Conner (a researcher at the Pacific Northwest National Laboratory). Here are some excerpts from Energy Design Update articles reporting on the findings.
EDU, November 2000: “An Unexpected Setback for Programmable Thermostats”
New field studies from Wisconsin and Florida suggest that programmable thermostats aren’t the prodigious energy-savers we’ve been led to believe and may in some situations actually increase energy use. “Before we did this study, I was sold on programmable thermostats,” says researcher Monica Nevius with the Energy Center of Wisconsin (Madison, Wisconsin). “It was a shock to me when we discovered that they have virtually no effect on energy savings.”
In 1998 and 1999, Nevius and fellow researcher Scott Pigg surveyed 299 homeowners in Wisconsin, constituting a representative sample of the state’s population and housing stock. As shown in Table 1, about two-thirds of those surveyed used manual thermostats to regulate their heating systems, while the rest owned programmable models. In-depth personal interviews were subsequently conducted with 30 of the homeowners to probe their personal attitudes toward energy conservation and thermostats. In fact, one of the main purposes of the study was to find out how homeowners’ attitudes toward energy conservation affect the way they use their thermostats and other energy-related behavior.
The results suggest that the owner’s attitude toward energy conservation is much more important than the technology. “We found that homeowners who are inclined to set their thermostats back will do so regardless of the type of thermostat they own and those who are not so inclined won’t do it regardless of the type,” Pigg explains. “Forty percent of the homeowners with manual thermostats set their thermostats back. Those who don’t aren’t eager to have a programmable thermostat and probably wouldn’t use one if they had it.” ...
Even Worse Results in Florida?
Preliminary findings from a Florida study on programmable thermostats appear to be even more negative than those from Wisconsin. Researcher Danny Parker, with the Florida Solar Energy Center, tells EDU that he’ just completed a field study for Florida Power Corp. (FPC) that monitored the end-use heating and cooling in 150 homes and broke out the results according to the type of thermostat installed.
“Within our project, we had 19 homes with programmable thermostats that showed evidence of increased consumption and peak demand,” Parker says. “This is just the opposite of what the HERS rating and Energy Star Home Program now estimate.” Parker says that he measured interior temperatures and space-cooling demand profiles at 15-minute intervals and found that people with manual thermostats were “much more likely to set up their thermostats than those with programmable models — just the opposite of conventional wisdom.”
Part of the problem, apparently, has to do with that old bugaboo: complexity (or, if you prefer, the “technological nuisance factor,” which is what keeps a lot of people from programming their VCRs). The manual thermostats are easy to operate and set back, Parker theorizes. But people with programmables tend to leave them at a constant setting because they’re too hard to program.
* * * *
EDU, January 2001: "Surprise! There are People Inside Those Buildings — Or, Why Programmable Thermostats Don’t Deliver the Promised Savings," by Craig Conner
A large field study conducted by Pacific Northwest National Laboratory concluded that the energy savings delivered by programmable thermostats are significantly less than advertised. Our findings square with those documented by the Energy Center of Wisconsin and reported in the November EDU. We concluded from our work that the value of programmable thermostats has been greatly overestimated because the mere presence of the thermostat doesn’t necessarily alter the homeowners’ behavior. In fact, our measured data suggests a nearly equal probability of setback with and without programmable thermostats. In short, the occupants control the thermostat and not the other way around.
Response to Matt Edwards
Matt,
You asked a question about the use of your electric resistance space heater: "Am I crazy for heating with this instead of my heat pump?"
No, you are not crazy. But you probably aren't saving any money.
Electric-resistance space heaters are 100% efficient, while air-source heat pumps have efficiencies in the 200% to 300% range. In most cases, you'll save energy by running your air-source heat pump instead of an electric resistance space heater.
There are two exceptions to this rule:
1. When it gets very cold outside, most air-source heat pumps lose efficiency, and many are programmed to turn off. The temperature at which this occurs varies; it may be at 25 degrees F for a run-of-the-mill U.S. heat pump, while it may be at -17 degrees F for a modern ductless minisplit unit from Japan.
You should find out more about the specifications of your heat pump so you know when this occurs. Most American heat pumps switch to electric-resistance heat when temperatures are very cold. That's exactly the same type of heat delivered by your "infrared" space heater.
2. If you turn the thermostat down low for most of the rooms in you house and heat just a single room with an electric resistance space heater, you may end up using less energy than you would to heat the entire house with a more efficient source of heat like a heat pump.
Bubble foil wrap
Martin, you say you wouldn't use bubble foil wrap anywhere - I installed a bubble foil wrap on my electric hot water tank and have been wondering if it provides adequate insulation to reduce standby loss. I've considered building a structure around the tank to add more insulation - do you think there's value in adding more R value to my tank or is the foil wrap enough for this application? Thanks for your thoughts and great article!
Response to Mark Fredericks
Mark,
Foil bubble wrap has an R-value of about R-1 -- that's not much.
Here is a link to a water heater blanket that is much better -- it is rated at R-10:
http://www.energyfederation.org/consumer/default.php/cPath/3499_4409_4095
More information on water heater blankets:
http://www.lower-my-energybill.com/water-heater-blanket.html
LED update?
Martin,
I understand it isn't possible to keep all articles on a website up to date but if someone reads this without catching the 2009 date, they might miss out on the very easy and increasingly affordable energy savings provided by LED lights. I think LEDs now (2012/2013) provide 50 to upwards of 80 lumens per watt). I'd suggest a quick edit.
Response to Keith H
Keith,
Thanks for your comments and your excellent suggestion. I have updated this article with a postscript to reflect your concerns.
One good use for Tyvek
Love the articles. Despite the inflated early claims of Tyvek, I love the stuff. I cleaned up and furred out the walls of my unfinished 1500-sqft basement in my 1893 Victorian energy hog. I re-wired my electrical and lighting, insulated appropriately, and covered the walls and ceiling with Tyvek. I do not have any moisture problems and the Tyvek gives a clean look (sort of) to the walls, encapsulates dust, is cheap and simple to install, the material is strong and easy to wipe down. I don't want to live in my basement, so I do not want to put up sheetrock, and I love having a tidy, clean basement for storage and utilities. I nominate myself for the best use of Tyvek award...
Response to Francis Whitby
Francis,
1. The product discussed in this article is not ordinary Tyvek. It is a rarely used product called Tyvek ThermaWrap.
2. Leaving exposed Tyvek in your basement probably violates fire safety codes. The appropriate material to install in that location is gypsum drywall, paperless drywall, or cement backerboard.
User interface and programmable thingies
Ladies 'n' Gents,
I work in an almost-completely unrelated industry, but I'd like to note that we sometimes pay lip-service to a product-development principle that is supposed to be a rule:
- The more you get the human out of the picture, the more reliable and predictable and successful the operation.
Once we get a few early-adopter, or feature-driving customers to test and refine the feature, so it represents what a large portion of the market should (we hope) want, we introduce it with the best defaults we could discern from the "Beta" period and with a fill-in-the-blanks set-up, where the interface asks questions and fills in a summary, and then the user is asked. "Is this what you want?" before they are all implemented. Sometimes, our field experience will suggest certain other sets of feature settings that other industry segments might prefer for their needs, and then we can include those in future iterations of the product as templates. "If your application is HR, consider starting with hrtemplate. If your application is banking, consider beginning with banktemplate. etc."
Getting back to the topic at hand, I notice that some programmable thermostats I've encountered have some grouped options for settings. Weekday/Weekend, Vacation, Summer, Winter... I've also noticed that most programmables make setup a real beeyatch for anybody who works shifts. For that you'd want something more like your laptop or smartphone than a little screen with low-contrast letters and symbols and a grand total of five buttons.
A deterrent that I encountered some years ago, that might no longer be a problem, is that a programmable would lose its little mind at some point, and we'd discover that it was back to factory default or had assumed some state never envisioned by god nor man. It would get re-configured and would work fine for a while..... and then one day go nuts again. It wouldn't yell or blink, it would just switch heat or cooling on and off at odd times, until somebody noticed.... at which point, the somebody would be grumpy or in a hurry and would just override, which would go on until somebody got up the gumption to dig out the manual and program the dratted device again. Might have been lightning or other environmental occurrences that knocked the thermostats for a loop; we never knew. Replacing didn't change much. But the last time I recall it being an issue was before 2010. The current house, it's happened only once that I recall.
Smart thermostats
Wifey-dear and I have been avoiding getting a so-called smart thermostat, and when we get new appliances, we do what we can to defeat features that would let the electrical utility (or hackers) exert external control on our heating and cooling and on the operation (or reporting of operation) of appliances. Mainly, we like our privacy. But also, with her 90-plus-year-old mother in the house, we don't want some bureaucrat being able to reach in and shut off the AC on the hottest, muggiest day of the year, for example.
The company that I work for makes encryption and data-protection equipment and software, that is used in many, many, many places and industries and governments around the world, but one that we've aggressively pursued is smart metering. Somebody else makes the meters and I think a branch of our company makes the chips that go in your new washer to tell the utility when and how you are using it, but my gang makes the back-office equipment to secure the upstream end of the data transactions. We do it very well. Never been hacked. Your data is safe with us...... just maybe not with our customers..... As soon as you introduce the human factor, you introduce vulnerability. All the collected data is in an encrypted, protected database, but some employee exports a million records to an unencrypted CSV file that they keep on their laptop, that gets stolen from their car.... you get the idea. Oh, and their password to the laptop was "PASSWORD"....
Anyway, notwithstanding usage and status data that is volunteered by your newer appliances, either via wifi or just out through the power connection, your utility has ever-more sophisticated ways of extracting info from the meter on your outside wall.
The power that your house consumes all goes through that meter. Smart meters now monitor and report the usage in real time, if desired (desired by the utility... they don't care what you desire). They have very sophisticated software that examines the moment-by-moment usage for patterns. It can tell when you've switched on your oven or a burner on the stove, by the pattern of the surge. Same idea for your furnace fan and anything motorized. Every device has a signature profile of electricity draw, and those can be teased out of the combined waveform that is your ongoing usage.
Now add in the data stream from the chips in your newer fridges, washers, dryers. At least those can be mostly defeated by plugging into a high-end power-conditioner block that filters out the signals imposed on the power line. But as they say, you're not actually paranoid if they really ARE out to get you. :-)
You can't readily filter out the signals to/from your smart thermostat to/from the local electrical utility, because it's usually powered by a DC line off your furnace.... so you would need to isolate the input power to your furnace.
Just some little things to keep at the back of your mind as tech gets more and more helpfully intrusive.
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