There are many things that can affect home energy costs through heat loss in the winter or heat gain in the summer. Heat loss/gain can be through radiation, convection, or conduction. One way to measure how cost effective it is to lower energy costs is to have an energy audit done on your home to determine ways to reduce energy costs through controlling these three effects.
First let’s look at the ways that radiation can affect energy costs. Any time there is a temperature difference between two surfaces, radiant heat will flow from the warmer surface to the colder surface. Take a home water heater for instance. It is hot inside and the wall surfaces around it are typically cooler. Heat will radiate from the warm water to the outside surfaces and increase energy costs to keep warming up the water. Water heaters are typically insulated to reduce conductive heat loss but not for radiant heat loss. A low cost fix for this radiant heat loss is a radiant barrier wrap around the water heater. A radiant barrier is a aluminum foil like material covering both sides of a section of bubble insulation. This will reflect the radiant heat loss back into the heater to save energy. The same effect occurs in crawl spaces and attics where radiant heat from the sun can cause heating in the summer which increases cooling costs in the home. The opposite effect happens in the winter where radiant heat from the home is lost through the attic and knee-wall spaces. A radiant barrier in the attic and in knee-wall areas can significantly reduce heat loss or gain through radiation.
Conductive loss or gain is the traditional way to reduce energy costs through insulation. Attic insulation is the most important and needs to have a heat resistance factor of R-30 or higher. Many homes are insulated with R-17 fiberglass insulation. This fiberglass insulation settles over the years and can drop to R-9 or less after 20 years or so. A new insulation material made of ground up newspaper cellulose that is impregnated with a chemical fire retardant is far superior to fiberglass and the fire retardant has a borax component that roaches and other bugs and animals hate. This is a real plus to keep these out of your home.
Last but not least is convective heat loss or gain. Convective air currents flow through holes and cracks in your home that are typically around electrical outlets on outside walls, and through cracks around pipes and in wood joints in your home. These “leaks” are caused by an effect called the “chimney effect”. Most people know that heat rises in a chimney. Most don’t realize that the hot air that rises is replaced with cooler air that has to come from somewhere. That somewhere is the cracks and holes in your home that let hot or cold air from the outside to enter your home and increase your cooling or heating costs. This same effect happens with your entire house. The attic is the top of the chimney and your house is the bottom. When the attic heats up, the hot air rises out of the roof vents and pulls air through the “leaks” in your home. This loss of hot or cold air from these leaks needs to be stopped by sealing these leaks.
By utilizing methods to stop heat loss or gain through the three primary heat exchange methods of radiation, conduction, and convection, a homeowner can substantially reduce their energy utilization, lower their “carbon” footprint, and save money over the long term with lower energy bills. A great side effect is a more consistent temperature throughout your home which eliminates the hot or cold spots that most homes have and make the home more comfortable. Make your home a green home.