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Your house’s defense against rising energy costs

by Steve McKee on February 12, 2006

You may have noticed that utility bills are up. Way up. Fortunately there are devices and measures available for your home that can cut down on your power bill. Some have to be built-in from the start, some can be added later. Some actually come to us from NASA (I’m not kidding) and get incorporated in invisible ways into our houses with things like films inside windows and heat-reflecting coatings in roof panels. It’s the invisible part I like. We get the benefits without even having to notice anything different about our homes.

Some of these items (like the low-E glass and the radiant barrier roofing that I describe below) are becoming requirements, actually mandated by building codes. But that’s okay, because these are things you will want to have in your home anyway, assuming you are a sensible person.

Low-E glass
“Low emissivity” glass is too cumbersome a name, so everyone just calls it “Low-E” glass. This glass is created by the addition of a film inside the sandwich of the two glass panes that make up modern windows. In the same way that doubling the layers of glass was a boon for energy efficiency starting in the 1970’s, this low-E film is scoring big these days for energy saving. It blocks radiant heat while allowing visible light to shine through. In the summer it keeps the heat out and in the winter keeps the heat in. It also will block something like 80% of ultraviolet light (various websites differed on this figure) which will greatly cut down on the fading of carpets and furniture.

A house with low-E film in the windows may save as much as 13 to 16% on energy bills compared to a house without it, said one website I visited.

To look through a window with low-E film is to look through a normal clear window. I say this so that the following sentence isn’t too off-putting. The film is actually an ultra thin layer of metal. I’ve looked through samples of both types of glass side by side and the glass without the film was just slightly brighter. I wouldn’t have known there was a difference unless I saw them side by side.

Low-E glass is becoming standard issue in windows these days, and a requirement in new construction and remodels, so you don’t have much choice. But that’s okay by us because it’s just so darn beneficial.

Tankless water heaters
This new generation of water heaters can supply hot water without need of a storage tank. These heaters are about the size of a small suitcase and go in the locations that a regular water heater would go. They have a gas burner and a metal flue that vents the exhaust gas out through your roof just like a traditional water heater. (Because of this you can easily replace an old water heater with a tankless one in the same location.) What’s different is that there’s no big fat tank of water that needs to be kept hot all-day-and-night when you’re at work or away on vacation.

It saves energy by heating the water only when you need it. When a hot water faucet is turned on somewhere in the house it starts regular unheated water flowing through the unit which activates the gas burner. This water passes through a coil that is getting blasted with flame. As it leaves the coil it’s hot. It’s as simple as that.

They are sometimes called “on demand” water heaters, a name which makes sense. Please don’t call them “instant” water heaters (as they often are called), because they’re not. You still wait for the hot water to travel through the pipe to your showerhead, just like with a traditional water heater. (We’ll talk about recirculation pumps another day.)

The supply of hot water is limitless because there’s no tank to run out. The caution you need to take is to make sure the heater is sized adequately for your house. There might be limitless hot water over time, but there are limits to how much can be generated at the same time for multiple users. Make sure you get one adequately sized for your needs. There are complex formulas for this, but I’ve also seen manufacturers make it simple: How many showers might you have running at once?

The tankless heaters cost about $600 to $1000 which is pretty much double the cost of traditional forty gallon water heaters which run about $300 to $500. That should mean they pay for themselves in gas savings within several years. (That’s a tough one to nail down exactly because of numerous variables.) It’s a good “green” choice; there’s not too much anguish deciding on this one, given its many advantages.

Radiant barrier
If you’ve seen OSB panels going on roofs under construction and these panels look like plywood but have a shiny silver underside to them, you are looking at the future, my friend. This silver colored film is a radiant barrier, capable of blocking radiant heat (similar to the heat blocking traits of the Low-E glass mentioned above.) The main benefit here is the way it keeps your attic cooler during hot days.

A comp shingle roof can hold a lot of heat. (Like you needed me to tell you that.) The radiant barrier on the roof panels under the comp shingles keeps much of this heat from radiating through your roof framing into your attic and producing a big cell of extra-hot air hovering right over your family room and bedrooms on the very days and nights that you don’t want it.

You can also have this radiant barrier installed in a variety of ways apart from the roof panels because it also comes as flexible sheets (sort of looks like aluminum foil, but wider and tougher and less crinkly.) These sheets can be used to wrap ducts in your crawl space or attic, wrap your 40 or 50 gallon water heater, or used to completely cover your attic insulation. I used a company called Eagle Shield out of Dublin ( who provided labor and material to do all three of these things in my house. They were a good company that I ‘m happy to plug.

Thermostat activated attic fans
These have been around awhile, but I feel compelled to mention them here for their potential to help cool a house without need of an electricity guzzling air conditioner. Especially in Benicia where we have natural breezes to keep us cool most of the time . . . except for those seven or eight days each summer when a high pressure system builds over Sacramento or Nevada and shuts down our onshore sea breezes. On those evenings we all sit with our windows open and no air moving. Eventually the night air cools, but there in our attics remains that big mass of extra hot air, just sitting there, keeping our houses too warm into the night in spite of the cool outside air.

An attic exhaust fan, positioned in your attic to blow either out a “roof jack” (metal roof outlet) or out a gable-end vent (preferred because it’s less obtrusive) can get that heat out and the cooler air into your attic. I recommend placing these fans at the east or northeast ends of your attic so that the fan will work with the natural wind direction in Benicia. You can even use these fans to get a head-start on staying cool the following day by filling your attic with cold night air.

Adding insulation
A classic solution to be sure. And one that’s not hard to understand either. The easiest to add (and the most beneficial) is the insulation that you add to your attic. If you’re in an older home which currently has wimpy amounts of attic insulation, this will make a huge difference. (You should have something around ten inches in an attic these days.) The insulation can be blown in by the pros or rolled out in batts (go for R-30 thickness to get ten inches and don’t bother to get it with the paper vapor barrier.)

And more
There are also things like photovoltaic solar panels (dark-blue metallic looking) that are mounted on your south-facing roof to generate electricity from sunlight, but that subject deserves a whole column to itself at a later date.

I thought you might appreciate knowing about these items. They help offset the fact that houses are tending to get bigger with more elaborate lighting schemes, more air conditioners and overall more energy use.


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