The blackouts and brown-outs in California during the last year appear to have been a wake-up call for the nation.

Home Depot reported in early July that the purchase of energy-saving products helped boost profits during the first half of 2001. The Atlanta-based chain of home centers said that sales of insulated windows and blinds, light dimmers, fiberglass insulation, programmable thermostats, weatherstripping and light-reducing window film had risen 25 percent.

Sales of fluorescent light bulbs and water-heater insulating jackets more than doubled in the same period, Home Depot said.

Although home-construction techniques have favored energy-efficiency since the gas crises of the early and late 1970s, the majority of American houses were built in times when gasoline was a 25 cents a gallon or less and no one had qualms about raising the thermostat because there was a seemingly-endless supply of fuel oil, natural gas and electricity.

To compensate, homeowners need to retrofit older houses to reduce energy costs.

Let's look at some of things on which Americans spent their money in the last six months, and see how they lowered energy costs:

Replacement Windows

The biggest test of the energy-efficiency of a replacement window is the gas, electric or oil bill for the following year. Double-pane windows with low-e (emissivity) coating can reduce heating bills by 34 percent in cold climates, compared with uncoated, single-pane windows, according to the Alliance to Save Energy, a Washington, D.C., advocacy group.

The low-e coatings let in visible light but block radiant heat losses to cut heating bills. The windows should have solar control, or "spectrally-selective," coatings to block solar heat gain to save cooling energy but let in visible light.

Windows should have insulated frames. Metal frames without insulation are the least efficient. Vinyl, insulated vinyl, fiberglass, and wood frames are more efficient.

The invisible gas filler in a double-pane window is critical to energy efficiency. Instead of plain air, high-efficiency models use argon or krypton gas, which conduct very little heat and help the window's insulating properties. The material used to create the separation between the two panes of glass, called a thermal break, was traditionally metal. New materials are better-insulating and make the overall window more efficient.

Window Film

First used in commercial buildings with large windows, but then made available for home use, the film is applied to the glass to reduce infrared solar heat and ultraviolet radiation but let in light. Some of these window-film can filter out as much as 98 percent of the heat while letting the light in. It can cost several hundred to several thousand dollars for an entire house.


The boom in residential construction in 1998-99 created a shortage of fiberglass insulation and boosted the price, but the economic downturn has again made it one of the least-expensive and easiest ways to control the climate indoors.

The attic is the easiest place to insulate. Fiberglass or cellulose insulation installed between the joists will keep warm air from rising higher than the top floor of your house and the heat of the sun from making that top floor even hotter in the summer.

Insulation is measured in R-values. The higher the R-value, the better walls and the roof will able to resist the transfer of heat. The federal Department of Energy recommends ranges of R-values based on heating and cooling costs and climate conditions.

For example, attic insulation should have an R-value of R-49 in a very cold climate such as New Hampshire and a very warm climate such as Dallas. The goal is to block the transfer of heat through the roof, whether it is coming from outside or inside.

R-11 to R-28 insulation is recommended for interior walls, again depending on the climate.

Some fiberglass insulation is paper-faced, which makes it easier to handle and install. A roll of paper-faced R-19, for example, costs $28 for enough insulation to cover 87.18 square feet.

Programmable Thermostats

A good one should cost close to $100. You can save as much as 10 percent a year in both heating and cooling costs by adjusting the times you want the furnace or central air system to be turned on automatically.

Light Dimmers

They typically cost $16 to $29, but says -- says Baltimore Gas & Electric, a big utility, you can "reduce lighting intensity, increase the life of the bulbs and save energy." However, BG&E says, "do not use dimmers on compact fluorescent bulbs."


Tape, felt or foam, costs from under $1 to $12, depending on the level of sophistication. An easy and quick way to stop air leaks.

Fluorescent Bulbs

Although they cost more than incandescent bulbs, they are more efficient and can last six to 10 times longer, thus paying for themselves over time.

Water Heater Jackets

They cost under $30, but if you put one on an old or inefficient water heater, it is a waste of time. Water heaters tend to last 10 to 15 years, so as the date approaches, consider an energy-efficient model. They, like fluorescent lights, cost more but save enough money over the long term to pay for themselves.

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