The Half Plan Reducing Your Carbon Footprint, Part One:

Thermal Gains

Inside this Article

The author installing triple-wall polycarbonate glazing
The author installing triple-wall polycarbonate glazing.
Thermal Shades
Thermal Shades eliminate 1,525 lbs. CO2 per year
Insulating Panels
Insulating Panels eliminate 1,100 lbs. CO2 per year
Storm Door
Storm Door eliminates 100 lbs. CO2 per year
Electric Mattress Pads
Electric Mattress Pads eliminate 510 lbs. CO2 per year
The author installing triple-wall polycarbonate glazing
Thermal Shades
Insulating Panels
Storm Door
Electric Mattress Pads

Almost all human activities impact the environment, but it’s only been in the past two centuries that we’ve witnessed a marked increase in the atmospheric concentration of carbon dioxide (CO2) as a result of one main activity—burning fossil fuels for everything from home heating to electricity generation to transportation.

An average American contributes 40,000 pounds of CO2 each year: the equivalent of making almost two complete trips around the globe in a 20-mpg SUV. Many scientists say that our overloading of the atmosphere with CO2 is increasing the severity of storms and droughts, and having an impact on ecosystems worldwide. Although global warming’s full-scale impacts are difficult to predict, researchers say that its probable effects—water shortages, coastal flooding, rising agricultural pest populations, and habitat disruption—will be far reaching.

The good news is that taking steps to minimize your carbon footprint—the total amount of CO2 you generate each year—can make a difference, both for the planet and for your pocketbook. Conserving energy and improving your home’s energy efficiency will lower your heating and electricity bills, and driving a more fuel-efficient car can save you hundreds of dollars at the pump each year.

Cut Your Consumption

“Half” is my family’s plan to reduce our energy consumption and greenhouse gas emissions by 50 percent. We took on more than 20 projects that fit our skill levels and particular household needs. You can follow our progress—and implement your own plan—over the next few issues of Home Power, where we’ll describe seasonal projects we completed at our house, and give estimates of cost, economic return, and greenhouse gas reduction.

Window Dressing

Our home, with its large expanses of east-facing, double-glazed windows, doesn’t make heating easy. To minimize heat loss and reduce air infiltration, we added two types of thermal shades. Both are accordion-pleated, but one style has an “Energy Track” on the sides (see photo), which prevents air from flowing around the edges of the shade. The shades’ manufacturer claims R-values of R-2.8 without the track and R-4.3 with the track, giving total R-values of 4.8 and 6.3, respectively, for the windows in my home.

The energy savings for improving window R-values by using storm windows or thermal shades can be estimated using the Insulation Upgrade calculator (see Access). You will need to know the window area, the existing window’s R-value, and the improved R-value. Single-glazed windows have an R-value of about 1; double-glazed windows about R-2; and double-glazed, low-E, argon-gas-filled windows about R-3. More exact values can be found at using their Window Selection Tool. A more precise method would be to use RESFEN, a free software program that provides an hour-by-hour heat loss simulation (see Access).

Project 1: Custom Thermal Shades

Up-front Cost: $1,086 (8 shades, various sizes, 140 sq. ft. total)

DIY Labor: 3 hrs.

DIY Difficulty: 3 (on a scale of 10)

Annual Energy Savings: 3,159 KWH or 117 gal. of propane*

First Year Energy Cost Savings: $258 (117 gal. of propane at $2.20 a gallon)

Projected 10-Year Savings: $4,109 

Annual CO2 Reduction: 1,525 lbs.

Energy Use Reduced: Propane

*For details on the assumptions and calculations used to determine energy and dollar savings, see

More Panes, More Gain

Oddly shaped windows are architecturally interesting, but can be a heat-loss nightmare, and difficult to insulate with any kind of conventional thermal shade or shutter. Customized interior storm windows made from triple-wall polycarbonate glazing can boost insulation values by an additional R-2.5, while still allowing daylight in and a (slightly distorted) view out.

Project 2: Insulating Panels

Up-front Cost: $450 (for 6 panels, various shapes, 134 sq. ft.)

DIY Labor: 8 hrs.

DIY Difficulty: 4

Annual Energy Savings: 2,700 KWH or 100 gal. of propane

First Year Energy Cost Savings: $220

Projected 10-Year Savings: $3,500

Annual CO2 Reduction: 1,100 lbs.

Energy Use Reduced: Propane

A Perfect Storm

A smaller, but still significant, project was adding a glass storm door to the front door, which helped reduce the thermal losses for both conduction and infiltration. By replacing the glass with a screen in the summer, it also allows for better ventilation in warmer months.

Project 3: Glass Storm Door

Up-front Cost: $200

DIY Labor: 3 hrs.

DIY Difficulty: 4

Annual Energy Savings: 216 KWH or 8 gal. of propane

First Year Energy Cost Savings: $18

Projected 10-Year Savings: $270

Annual CO2 Reduction: 100 lbs.

Energy Use Reduced: Propane

Wise Drying

The advantage of venting a dryer to the inside is twofold: you recover much of the heat that was added to dry the clothes (about 2.2 KWH per load); and you avoid bringing in cold outside air to make up for the air that the dryer is pushing outside.

To vent to the inside, you need 1) a dry climate, 2) an electric—not gas—dryer, and 3) a way to catch the lint in the dryer exit stream. (Gas dryers should never be vented inside, since the vented air contains combustion by-products. Electric dryers should only be vented inside if your climate is dry—be alert for moisture problems, such as mildew buildup and excessive condensation on windows and door frames.)

The simplest way to vent the dryer to the inside is to separate or cut the dryer vent pipe, and duct-tape a pair of pantyhose as a lint trap over the vent. To prevent cold airflow, block off the vent pipe leading to the outside. Be sure to regularly check the new lint trap for clogging and keep good air movement through the dryer. Once warmer weather has arrived, you can splice the cut pipe back together to vent the hot air outside.

Project 4: Dryer Vent

Up-front Cost: $20 (tubing and a lint filter)

DIY Labor: 2 hrs.

DIY Difficulty: 3

Annual Energy Savings: 630 KWH

First Year Energy Cost Savings: $63

Projected 10-Year Savings: $1,002

Annual CO2 Reduction: 286 lbs.

Energy Use Reduced: Propane (reduces space heating needs)

Cold House, Warm Bed

In our frigid Montana climate, keeping warm can be a struggle—and heating bills can eat a household alive. Although we set the bedroom area thermostat to 62°F at night, the bedroom’s forced-air furnace would still cycle off and on frequently.

Our solution was to use electric mattress pads (aka bed warmers), and heat the bed instead of the room. Unlike electric blankets, the power consumption for mattress pad heaters is very low (about 13 W each). Using the pad heaters at night allows us to turn off the furnace that heats the bedrooms. The savings in propane is considerable, the comfort is outstanding, and—even better—there’s no furnace noise.

Project 5: Electric Mattress Pads (2)

Up-front Cost: $125 (for a king-size bed)

DIY Labor: 0 hrs.

DIY Difficulty: 0

Annual Energy Savings: 1,270 KWH or 47 gal. of propane

First Year Energy Cost Savings: $103

Projected 10-Year Savings: $1,624

Annual CO2 Reduction: 510 lbs.

Energy Use Reduced: Propane

Next Issue—Trimming Your Waste Line 

Gary’s family puts their household on an energy-slimming diet, and offers more tips on how you can cut your electricity use and reduce your household CO2 emissions.

Your Solutions

What smart steps have you taken to reduce your carbon footprint? Write to us at If we choose to print your projects, you’ll get a free Best of Home Power CD-ROM and a one-year gift subscription to send to a friend or family member.


Gary Reysa, Build It Solar Projects •

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