Incorporating solar energy into your home

Types of insulation
Bulk insulation
Bulk insulation reduces the flow of heat that occurs by conduction. It comes in several different forms.
• Batting and blankets made of materials such as rock wool, fiberglass, acrylic fiber, wool, and eel grass.
• Loose-fill material made from cellulose fiber.
• Rigid lightweight boards, such as polystyrene and polyurethane, and materials such as straw and wood fibers that can act as a lining when mixed with binders.

Reflective insulation
To be effective, reflective insulation must have an air space next to it. It reduces heat transfer by reflecting heat on its warm side and not emitting much heat on its cool side. Reflective insulation usually comes in one of the following two forms.
• Reflective foil laminate (RFL) is made from aluminum foil laminated onto both sides of a stiffer backing.
• Reflective coating on the underside of corrugated metal or on the back of plasterboard. Composite reflective and bulk insulation This type of insulation has reflective foil laminated onto one side of a bulk material.

Insulate for comfort
Effective insulation helps houses in both warm and cool conditions, as it slows down the transfer of heat in and out of a building, thus making the building more energy efficient in terms of heating or cooling costs. You can cut these costs by an estimated 20 percent by installing appropriate insulation in your home. Insulation is rated according to its suitability for different climates, so make sure you use the type most suitable for yours.

Where should you insulate?
Ceilings, walls, and windows are all candidates for insulation.

The ceiling and roof area is the most important spot to insulate, as it is there that a house loses most heat in winter and gains unwanted heat in summer. Reflective insulation is the best choice for preventing the warmth of the summer sun entering, while bulk insulation stops heat already in the house from escaping. Effective roof insulation, therefore, uses a combination of the two.

Walls can be insulated with rigid polystyrene boards, by injecting expanded polystyrene into the wall cavity, fitting bulk insulation between wall studs, and by fixing reflective foil laminate to the wall studs. You—or your builder—need to take care that insulation does not form a bridge in cavity walls for moisture to travel across. Vapor barriers are also necessary on the warm side of the insulation to prevent moisture condensing on both it and the wall surface. In a cold climate this should be at the inside lining, and in hot climates, where rooms are air-conditioned, at the outside lining.

Windows are a prime candidate for insulating, as glass is an excellent conductor of heat. Reduce heat lost at windows by using any of these methods.
• Fit heavy curtains and pelmets made from material with a close weave. The air between the curtains and window acts as insulation.
• Install insulated panels, such as shutters, at the window, either inside or out.
• Double glazing is a good option for colder climates. Two sheets of glass are separated by a gap of one-half to three-quarter inches.

The value of insulation
The effectiveness of insulation is expressed as its R value. The higher the R value, the greater the insulating effect. As the best insulation for your house depends on its climatic location, you should contact local energy information centers for advice.

If you are making alterations, the existing structure will also affect your needs. Roofing generally requires insulation with a greater R value than external walls.

Read more in Decorating & Design and Green Living