Insulating Materials: Building Construction and Location

Insulating materials are specifically designed to reduce the rate of heat transmission through ordinary construction materials to an acceptable level. A dry material of low density is considered a good insulator; however, in addition to this characteristic, it must also have a conductivity value of less than 0.5.

The conductivity value of a material is a purely arbitrary one determined by the amount of heat that flows in 1 hour through a 1 inch thickness of a material 1 square foot in area with the temperature exactly 1 degree F higher on one side of the material than on the other.

Air spaces, or air spaces bounded by either ordinary building materials or aluminum foil, also provide some insulation, but not to the degree formerly thought possible. Dead air spaces in building walls were once considered capable of preventing heat transmission in a manner similar to the space between the walls of a thermos bottle. Later research proved this to be a somewhat false analogy because the air in such spaces often circulates and transmits heat by convection.

Air circulation can be checked by filling the hollow space with an insulating material that contains a great number of small confined air spaces per unit volume. This stoppage of air circulation is what produces the insulating effect, and not merely the existence of the air space. Under these circumstances, it is obvious that the most practical method of insulation is to fill the area in the walls with a material containing these minute air spaces.

Several manufacturers produce insulating materials in a variety of shapes and forms for insulation in houses and other buildings. Frequently, instructions for the installation of the products will also be provided by the manufacturer. Local building supply outlets and lumber yards will often be very helpful, too, and will usually recommend the best way to install the insulation material.

Construction and Location
A masonry, common in many older homes, is a particularly poor thermal barrier. A typical masonry cavity wall has a thermal resistance equal to approximately 1in of ridged insulation. Exterior opaque masonry walls should have maximum U-value of 0.11, requiring insulation rated at R-7 or greater.

A new building (particularly a residence should be located so that the large windows in the main rooms face south to receive the maximum sunlight during the winter months. If possible, the building should be built in a location that offers some natural protection from the prevailing winter winds. Tight, well-insulated construction should be incorporated in the design of the building from the beginning. Although the initial costs will be somewhat higher, they will be effectively offset by the reduction in heating and cooling costs.

If a new Denver heating and air system is planned for an older structure, the existing insulation should be checked and, if necessary, repaired or replaces before the new system is installed.