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Common Misconceptions: Window BS

Wednesday, July 21st, 2010

Window Building Science or just plain window BS? You decide. A lot of home energy auditors feel that windows are over-sold, meaning that the typical window salesman exaggerates the benefits of new windows. Let’s run some numbers and you can decide, because in truth, like most things in building science, it all depends on the specifics.

For our example, we are going to use a 36” x 60” window, or 15 square feet. We’re also going to assume that our example home has an 80 AFUE natural gas furnace, meaning roughly that it runs at 80% efficiency. The home also has an air conditioning unit for cooling with an efficiency of 13 SEER, the federal minimum standard. The 80 AFUE furnace is probably about average and the 13 SEER A/C is probably a little better than most installed units. (Those homeowners in rural areas who have electric heat are going to have heating savings substantially higher than what we calculate below.) Further, we’re going to pretend this house is in St. Louis, Missouri (so it has 4900 HDD and 1527 CDD). So now we’re ready to go.

Let’s say we have an old single glazed wood frame window and we purchase a brand new ENERGY STAR replacement window for it. Uninstalled we could expect to pay about $109 for the new window. Remember, that’s uninstalled. Given the assumptions we made above, we can expect to save about $9.92 in heating costs and about $16.36 in cooling costs annually. In other words, that may not be a bad investment, especially if the windows are leaky and the installation cost wasn’t too exorbitant. By “leaky” here I mean air leakage since if they leaked water they’d probably have been replaced long ago – or should have been.

But most of us don’t have old single glazing type windows alone. They probably had storm windows added to them a long time ago, and that presents a completely different scenario. Replacing a single glazed window that has a storm window with a new ENERGY STAR replacement window (same price), we might expect to save only $3.14 in heating costs and $5.18 in cooling costs annually. It’s going to take some time then to pay off that new window. Now, if this is the meager savings I get with a single glazed window with a storm, you can pretty much assume that if you have an old double-glazed window which a window salesman is trying to get you to replace, that your savings wouldn’t be any better.

Ok, ok – let’s say we did have an old single glazed window without a storm. It would cost us about $46.00 to purchase a storm window for it (uninstalled again). Once installed we could expect it to save us $6.78 in heating costs and $11.18 in cooling costs annually. Wow! But, true, there is the hassle of putting them up and taking them down each year if you are so inclined to do so.

So that’s window building science in a nutshell. Given the savings above, it’s probably better to spend the window money for energy efficiency upgrades elsewhere in the home. But not always. There are some situations where new windows is a very good investment.

And finally, for those of you engineering types who just can’t put your pencils down, I’m using $1 for the cost of a natural gas therm and $0.086 for the cost of kWh (read this and weep, Californians). The U-values used for the window examples above are:

.9 – Single glazed wood frame

.3 – ENERGY STAR qualified window

.49 – Single glazed with storm window

That should be all you need to check my calculations.

Posted in Building Science, For Homeowners | No Comments »

Common Misconceptions: How Big Is Your A/C?

Wednesday, July 7th, 2010

I remember getting a haircut once when I was a boy and how the barber bragged and bragged at how big his rooftop air conditioner was. It was long ago, and so I don’t remember much other than that – only the blast of cold air streaming out of the supply register. He probably told everyone how many tons it was. Believe it or not, I do seem to remember it cycling on and off a lot.

The lesson today: don’t listen to your barber when getting an air conditioner. Bigger (than needed) is not better. It’s actually worse, and here’s why.

Air conditioning cooling has two components. It removes both sensible heat – that is, the air temperature, the heat you measure with a thermometer – and it removes latent heat. Latent heat is the heat energy stored in the air’s water vapor. We all know it takes heat to create steam. But once vaporized, that heat doesn’t just disappear, it is held by the water vapor in the air. In fact, in places like St. Louis (where “St.” stands for “Steamy”) a big part of what an air conditioner does is remove that humidity. If an air conditioner is sized too big, it cools the sensible heat down fairly quickly. The thermostat then switches off, but more times than not, it didn’t remove much moisture from the air because not enough air circulated through the duct work and over the air conditioning coils long enough. Walking into a home with an oversized air conditioner sometimes feels like you’re walking into a cave: cool, yes, but clammy. An air conditioner actually needs to run long enough for the water vapor in the air to condense on the coils. If it’s two big, it cycles on and off before it can do that.

In fact, on a really hot day, a correctly-sized air conditioner will run almost all the time.

Unfortunately, most air conditioning units are too big for the homes. Why? There are all sorts of reasons. Larger units cost more and so make more for the HVAC company. HVAC companies want to make sure you don’t call them back out because your house is too warm, and so that fudge some oversizing in. And, so on and so forth…

If you’re in the market for a new air conditioner, request that the HVAC company do a “Manual J” and show you their calculations. A Manual J is the industry standard method of determining how much cooling you home will need (both in sensible and latent heat). If they don’t want to do that, then move on to another HVAC company. (Plus, the Manual J already includes a calculation for those really, really hot days.)

The benefits are many. Properly sized units cost less than units that are too large. The home is more comfortable. They cool more efficiently. They need less fan power so there’s an electric and equipment savings there, too.

So, no Manual J, no business. It’s as simple as that.

Posted in For Homeowners | 1 Comment »

Common Misconceptions: Insulation Is All You Need

Tuesday, April 27th, 2010

Ask most homeowners whose utility bills are high what their homes need, and more likely than not they will reply “insulation”. One of the very first homes I audited was for a elementary school teacher who was a friend. She was going to buy more insulation for her home and thought she’d run the idea by me. I went over to her home and tested it with a blower door, and no amount of insulation was going to bring her utility bills down. It was one of the leakiest homes I’ve measured, still to this day. In other words, it had a lot of air moving through it. What most homeowners don’t realize is that insulation is only one side of the coin. Air sealing is the other. The two combined, an air seal and insulation, is what defines a good thermal barrier in the home, and yet most non-professionals only know about insulation.

A way to illustrate this might be the following example. Let’s say you want to go for a bicycle ride on a somewhat chilly day. Outside temperatures are in the upper 30’s F. If you put on your fleece jacket and hop on your bike, do you think you’re going to stay warm? Doubtful. Why? Because you know that cold air will sail right through that fleece rendering it next to worthless in keeping you warm. Put an outer windproof shell over that fleece and immediately you’ll notice a huge difference. In fact, it’s safe to say that you might quickly find yourself too warm. Not only is fleece (insulation) more or less worthless when air can circulate through it, by comparison it’s not even as important as the shell (the air barrier). If you’re riding that bicycle on a cold winter day and had to choose between a shell (air barrier) and a fleece jacket (insulation), which one would you choose?

Even still, in the building science classes that I teach for up-and-coming BPI home energy auditors, it takes awhile for this to sink in. Invariably when asked what can be done to an example home that is leaky, a couple of hands rise and blurt out “Add insulation”. This notion has been so ingrained in us by the pink, blue or beige insulation companies that it even takes some trained professionals awhile to get it. Oh, and that R-value printed on the insulation package? It was measured when the insulation was enclosed on all six sides in an airtight enclosure.

So the first common building science misconception is that insulation is all you need. While that may be true for a specific home here and there, it is most often incomplete. That insulation must be paired up and side-by-side with a good air barrier. Otherwise, that bike ride is going to be pretty darned cold.

Posted in DIY, For Homeowners | 2 Comments »

A Tale of Two Cities: Utilities’ Energy Efficiency Programs

Wednesday, April 14th, 2010

Not sure why this is a conundrum for some utility companies and not for others. After all, in this case they are both regulated by the same state Public Services Commission. Yet one has had long-standing and vital energy efficiency programs. Kudo’s to the other side of the state!

Program	Kansas City Power & Light (Kansas City, MO)	Ameren UE (St. Louis, MO)
ENERGY STAR New Homes Program	Yes $800 rebate $750 for HERS rating	No
Home Performance with ENERGY STAR Program (Existing Homes)	Yes Up to $1,200 in bill credits for a HPwES improvement	No
Discounted CFLs	Yes	Yes
Solar Rebate	Yes $2 watt installed	? – state requirement, but not found on website?
Energy Efficiency HVAC or Heat Pump	Yes Cool Homes Program provides up to $850 rebate	No
Energy Efficient Appliance Rebates	Yes Free programmable thermostat ($300 value)	Yes Dehumidifier, $25 Freezer, $50 Room A/C, $50

Posted in For Builders, For Homeowners, Random Thoughts | No Comments »

Wrapped Is (Usually) Bad

Tuesday, March 16th, 2010

I was walking the insulation aisle of a big home store today when to my dismay I saw wrapped fiberglass insulation is back. This is batt fiberglass insulation that is in a thin perforated plastic sheathing so that the fiberglass is contained in a tube of sorts. It’s supposed to be easier to handle. I’m not so sure about that, but I am sure that this type of insulation is usually bad news.

When I first saw this kind of insulation about seven years back, its maker made the claim that the insulation was safe to install over existing insulation (even though it’s wrapped in plastic, or, one could say, “faced”). They said because of the perforations in the plastic wrapping, it would still allow water vapor to pass through it. It doesn’t. The company (hint: they make pink insulation) isn’t making that claim now – or at least I didn’t see it on the label – but buyer beware! Don’t put this insulation over existing insulation and assume that it will breath. It absolutely simply doesn’t. I know, because I didn’t believe it then. I bought a roll, tore off some of the plastic wrapping (holes and all) and then using the perforated wrap I covered a steaming pot of water. Sure, some of the water vapor probably did escape through the holes, but a lot of it condensed on the underside of the wrapping. (Experiment with this yourself: take some kitchen plastic wrap and punch holes in it, then cover a glass that you just filled half way with steaming water, and watch what happens.) If you use this wrapped insulation, you invite the same potential condensation in your attic.

Demonstration of condensation

And what is “nice” about it, anyway? You really shouldn’t install it without a mask, eye protection, gloves, long sleeve shirt and pants, etc. anyway. At least I wouldn’t. (Once you cut the roll, you’ve exposed the fiberglass, and it’s no longer so “nice”.) Buy the regular unfaced batts instead. They’ll let water vapor through and, besides, they’re cheaper.

To me, this stuff is such a rip-off. I have had clients remove this type of insulation when I’ve found it in their attics over the top of older insulation. The most recent one was a widow, and she didn’t need this kind of headache. For all I know, perhaps her late husband installed it, thinking he was taking good care of their house. So, in addition to paying for the materials and the time (or expense) to have it installed, sorry to say but it now really needs to come out. (Fortunately, one of my recommended insulation contractors was willing to unwrap it for her and re-install the old fiberglass.)

Simply put, it’s not good for the durability of the home: it will allow water vapor to condense, and any water in a home where you don’t want or expect it can be a nasty thing. Think mold or rot. Besides, there are so many other good alternatives (unfaced batts, blown fiberglass, blown cellulose).

Posted in Building Science, DIY, For Homeowners, Professional Tips | 2 Comments »

The Still Misunderstood CFL

Wednesday, February 24th, 2010

After having conversations with several clients lately after recommending that they install Compact Fluorescent Lights (CFLs) throughout their homes, I discovered that some good information about CFLs is still not getting out. There seem to be two misconceptions, both having to do with the mercury contained in CFLs.

One complaint was that they contain any mercury at all (compared to incandescent light bulbs). But in the St. Louis area, where most of our electricity is generated by coal-fired plants, its actually a false argument. Let’s say “X” represents the amount of mercury contained in a CFL (which, by the way, has decreased dramatically over the years). Now, knowing that CFLs use less wattage than an incandescent light uses (for the same amount of light), let’s say then that “Y” represents the amount of mercury in the coal that is burned in order to generate the extra energy required to burn an incandescent light. Simply put, “Y” is greater than “X”. In other words, more mercury is released into the atmosphere from the burning of coal for that additional energy that would be required to light an incandescent light bulb (over the amount needed to light a CFL). Furthermore, with CFLs that mercury is contained, not released into the environment from the smokestacks of coal-fired plants.

This leads to the second misunderstanding; namely, that the mercury ends up in landfills when the CFL is thrown away. How good can that be? Well, that’s true… but it needn’t be so. Did you know that Home Depot and many Ace Hardwares in the St. Louis area now recycle burned out CFLs? They need to be put in a plastic bag but, other than that, simply take them to the return counter and drop them off. It’s that easy.

Posted in For Homeowners | 1 Comment »

Not A Big Fan of Humidifiers

Friday, February 5th, 2010

I’m not a big fan of whole house humidifiers.

I have one, myself, in my own home, but it has been turned off for years and I haven’t really noticed the difference. Most humidifiers are sold as a way to make a home more comfortable. True, they can reduce the static electrical shocks one experiences in a (very) dry home. The additional moisture in the air also contains a lot of heat (after all, how did it become suspended in the air?), and that makes the home feel cozier – just as a wet sauna take cozy to the extreme.

But, generally speaking, humidifiers may do more harm than good, especially in homes that are tight — and increasingly more and more homes are being tightened or are being built tight.

When the temperatures in this St. Louis area recently got down in the teens and single digits, I was barraged with calls about window condensation and about water droplets on the ceilings of closets or near an outside wall. Think about it: any time your raise the relative humidity you also raise the dew point. After a certain point it doesn’t take much of a lower temperature to facilitate condensation. Windows, being windows, have limits in their insulating value. If the temperature outside is in the teens or single digits, do you really expect your window panes to stay room temperature? Double-paned windows are a great improvement, but they can only do so much. Likewise, closet doors are often closed and don’t benefit as much from the conditioned air of the home: so they’re colder. Attics and roof structures in most homes were not built with insulating the perimeter in mind, and so the ceilings near the outside walls are usually colder, too.

In fact an argument could be made that the lower the outside temperatures (and therefore the lower the humidity out there), that’s all the more reason to turn off the humidifier. In fact, if you look at most humidifier controls, you set them by the outside temperature and they throttle back the humidity to next to nothing the lower the outside temperature. So what’s the point?

You’re only asking for trouble, because if water is condensing where you can see it, what about where you can’t? Inside your walls maybe? Somewhere underneath that nice blanket of insulation in your attic? And, most horribly, even behind picture frames and mirrors.

And so I get a call, show up at the home and make a beeline to the furnace. What do you think I find? Of course: a humidifier. Invariably.

As I wrote above, this is especially troublesome in tight homes. In a tight home, often the humidity that is generated by the people living in it (respiration), by cooking, washing, and bathing, generates more than enough humidity. In fact, in those homes moisture often still needs to be removed.

So what can you do? If you don’t know how tight your home is, get it tested. It’s that simple. If you’re wedded to your humidifier and you see moisture, then turn it off (or at least way down), especially when the temperatures outside drop. Even then, though, you have to live with the knowledge that you may not know about the condensation you can’t see.

Me? I just turned it off. And, like I wrote, haven’t noticed a difference.

Posted in Building Science, For Homeowners | 1 Comment »

“Energize Missouri – Appliance Rebate Program” Begins April 19

Monday, January 25th, 2010

Over $5.6 million will be available for rebates that target heating, cooling and water heating systems in Missouri. The U.S. Department of Energy approved the plan by Missouri Department of Natural Resources (DNR) for a new Energize Missouri Appliance Rebates program to be administered by DNR’s Energy Center. The Energy Center will implement the program using funds from the American Recovery and Reinvestment Act of 2009.

The program will help Missourians buy appliances at lower costs, reduce home utility expenses and benefit Missouri retail businesses. The Energy Center plans to launch the program on April 19, 2010 — at same time as Missouri’s second annual “Show Me Green Energy Star Sales Tax Holiday”.

The Energize Missouri Appliance Rebates program will provide Missouri citizens a rebate when they purchase a qualified ENERGY STAR gas furnace, air source heat pump, central air conditioner, clothes washer, dishwasher or one of many qualifying kinds of water heaters, including solar water heating equipment. (Unfortunately, ENERGY STAR refrigerators apparently do not qualify.)

Rebates will be for the following items and amounts:

Gas Furnaces – $125
Air Source Heat Pumps – $250
Central Air Conditioning – $100
Water Heaters-Gas Condensing- $150
Water Heaters-Gas Storage – $100
Water Heaters-Gas Tankless- $100
Water Heaters-Solar (With Gas Backup) – $500
Water Heaters-Electric Heat Pump- $150
Water Heaters-Solar (With Electric Backup) – $500
Clothes Washers – $75
Dishwashers – $75

Missouri residents should also check with their utility providers for other rebates that may be available for these appliances as well as for other ENERGY STAR appliances not included in Missouri’s program.

Rebates will be made on a first-come, first-served basis and will be discontinued when the rebate fund has been exhausted.

To be eligible for rebates purchases must be made after the 2010 starting date of the program, April 19, 2010. For a list of ENERGY STAR qualified appliances and equipment, visit the ENERGY STAR site.

Information and updates on Energize Missouri Appliance Rebates are available at the Energy Center website.

Posted in For Homeowners | 2 Comments »

New Lower Pricing

Wednesday, December 23rd, 2009

In honor of the recession, and of the laws of supply and demand, Show Me Home Energy Solutions is reducing the base price for a residential energy audit. This isn’t an abbreviated audit; it’s the same audit as before – performed to BPI standards by a BPI Professional – and is believed to be the lowest price for a home energy audit in the St. Louis metro area. Hopefully, by making an audit more affordable, more families will be able to make their homes more comfortable and energy efficient. See the services page of our website for more details.

Posted in For Homeowners | No Comments »

3 of 3: Consulting Pro’s & Con’s

Tuesday, December 1st, 2009

This is the third of three posts about the two common business models in the field of energy audits of existing homes. The first one introduced the two models, contractor and consulting. The second one looked at the contractor model.

Again, there are two distinct points of view when looking at these models: the homeowner’s point of view, and the audit company’s. We’ll look at the consulting business model from the homeowner’s point of view first.

The audit company employing the consulting business model performs the home energy audit, but doesn’t itself perform any of the work which the audit recommends. In other words, the consultant can tell you what about the house is deficient, and how to improve it, and usually even write the specifications for the improvements, but the homeowner will need to find someone else to actually do the work. Actually, this fact is what is most attractive about the consulting model to some, and most unattractive to others. Some homeowners absolutely love the fact that the consultant isn’t trying to sell them anything (beyond the audit, that is). The homeowner is nearly guaranteed an objective, unbiased report. On the other hand, this makes it harder for the homeowner because he or she then has to go out and get bids for the work. Most consulting auditors provide a list of recommended contractors, insulators, and what-have-you, but still the homeowner must do their own due diligence in the bidding and selection process.

Some don’t mind at all. A consultant might be the obvious choice for homeowner who wants to do some or all of the work themselves, and most consultants are pretty good at helping the do-it-yourself’er. Another advantage with the consultant approach is that the improvements can be phased in over time. They don’t have to be done all at once. The homeowner can do a little bit now, a little bit later, and then finish it all up even later, and perhaps avoid financing the work in the process. In any case, the homeowner is almost certain to only have the work done that needs to be done.

The consultant’s audit can be more expensive than the contractor’s, but not always. This is because the consultant must make their profit on the only service they perform: the audit. A contractor, as mentioned in the second post, often does the audit as a loss leader and makes their profit in the improvements.

Additionally, the quality assurance performed by a consultant is usually performed on every job, not just a percentage of them. In other words, most consultants will come back and do a “test out” after the improvements have been made in order to ensure that the work done for the homeowner was up to snuff. (Sometimes there is an additional fee for this, sometimes not.) One thing to note: the quality assurance only works if the homeowner takes advantage of it. Many times, the homeowner simply doesn’t.

From the home energy auditing business point of view, this consultant model only usually works for an individual or a company if they are also a HERS rater and therefore do new construction as well. Being a Green Rater for LEED for Homes also helps. In the Midwest, anyway, there usually isn’t enough business to focus on doing audits on existing homes only. The consultant almost certainly will need to diversify into new construction. The only exception to this might be in those states where there are additional state or federal incentives that either generate more business for the consultant, or add profit to each job (for example, via a payment for each home completed). One big advantage for the consultant in all this is that their own overhead can be extremely low. The majority of consultants run their businesses out of their homes. Once the equipment is purchased, usually the biggest operating expenses are for insurance and perhaps for on-going training.

As before, the key for the homeowner or the potential home energy auditing business is to weigh the pro’s and con’s of each model, and then decide which one is right for them. I hope these brief posts have helped in that endeavor.

Posted in For Homeowners, Professional Tips | 1 Comment »

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