As you begin the process of selecting the most efficient air conditioning system for your home, investigate the critical issues of system size, placement, installation, and contractor experience. Your goal is to obtain an efficient system by: sizing the system for the specific cooling load of your home; selecting and properly installing the thermostats or controls; designing a ductwork system to deliver the correct amount of conditioned air to each space; and sealing and insulating all ductwork.

Ceiling fans create a breeze, so room occupants feel cooler and more comfortable. With a ceiling fan running, you can raise the thermostat setting by 2 to 4 degrees during the cooling season with no reduction in comfort. Increasing the room temperature by even two degrees can cut your cooling costs 4 to 6%.

Air distribution or duct systems are designed to supply rooms with air that is “conditioned”—that is, heated or cooled by the heating, ventilation, and air conditioning (HVAC) equipment—and to recirculate or return the same volume of air back to the HVAC equipment. Your duct system has two main air transfer systems: 1) supply, and 2) return. The supply side delivers the conditioned air to the home through individual room registers. The return side picks up inside air and delivers it to the air handler of your central system where heat and moisture are either removed or added and then delivered to the supply side. All of the air drawn into the return duct(s) is conditioned and should be delivered back through the supply registers.

The efficiency of a gas (natural or propane) or oil furnace is measured by the Annual Fuel Utilization Efficiency (AFUE), which describes the heat produced from the energy used. This rating takes into consideration losses from pilot lights, start-up, and stopping. For example, a furnace with an AFUE rating of 80 converts 80% of the fuel it burns into usable heat. New furnaces usually rate in the mid-70s to low 80s, whereas older furnaces will be in the 50s or 60s. ENERGY STAR® qualified oil and gas furnaces have annual fuel utilization efficiency (AFUE) ratings of 83% and 90%, or higher, making them up to 15% more efficient than standard models. Unlike the Seasonal Energy Efficiency Ratio (SEER) and Heating Season Performance Factor (HSPF) ratings, the AFUE does not consider the unit’s electricity use for fans and blowers.

Mold has received a lot of attention of late because of high profile lawsuits and television news broadcasts that have highlighted the potential hazards and liabilities associated with indoor mold. What is mold? Molds, along with mildews, yeasts, and mushrooms, all belong to the kingdom fungi. Fungi are unicellular or multicellular organisms that primarily use absorption as a means to obtain energy from their environment, unlike green plants, which use chlorophyll to obtain energy from sunlight. The term “mold” describes unwanted visible fungal growth. “Mildew” is fungi that grows on fabrics or that causes plant disease. The term “yeast” is fungi that are unicellular when cultured.

Heating water is the third largest energy expense in your home, after heating and cooling the entire space; and, it can account for 15-25% of your utility bill. It’s not hard to see why a family of four, each taking a 5-minute shower a day under inefficient showerheads, can use 700 gallons of water in a week representing a 3-year supply of drinking water for one person! There are several ways to cut down the amount you spend on heating water: a) insulate your water heater and pipes; b) reduce the amount of hot water you use; and c) turn down the thermostat on your water heater.

The National Fenestration Rating Council (NFRC) offers a voluntary testing and certification program for thermal performance for windows and residential door products with glass. The NFRC does not conduct structural characteristics, such as impact-resistance, but rather serves as a complementary program that can test the whole window (including frame) for the following characteristics: U-Factor, Solar Heat Gain Coefficient (SHGC), Visible Transmittance, Air Leakage, and Condensation Resistance (see sample NFRC label) .

Mobile and modular homes are factory-built and generally differ in how much of the construction occurs at the factory. The greater the work at the factory, the less labor is needed where the home will be located.

Buildings should be designed and built to provide comfortable and healthy levels of relative humidity. They should also prevent both liquid water from migrating through building components and water vapor from being trapped in building assemblies, like walls.

The greatest source of wasted heating and cooling energy in a home is air leaks. If you have a pair of 6' 8" exterior doors in your home that do not have weather-stripping, you can easily have an opening of ¼" all along the edge where the doors meet. This ¼" gap adds up to a 20-square-inch opening to the outside. If you saw a hole this big in your wall, wouldn’t you want it fixed?

While a good heating, ventilation, and air conditioning (HVAC) system and other energy saving features can provide you with a comfortable indoor environment, it is even more efficient to prevent heat from entering the house in the first place. By designing a house with the right shape and orientation, and strategically locating rooms, you can save on energy costs for cooling and heating. If renting or purchasing, look for these same features in an existing home.

Air is made up of a mixture of gases including oxygen, nitrogen, and carbon dioxide. It also contains water vapor—water in the form of a gas. The temperature of the air determines how much water vapor it can hold: warm air can hold more than cool air. When the air is saturated, it cannot hold any more, and any extra water vapor will condense into liquid form.

Reflective insulation systems are made from aluminum foils with a variety of backings such as roof sheathing, kraft paper, plastic film, cardboard, bubble wrap, etc. The resistance to heat flow depends on the direction of heat flow with this type of insulation most effective in reducing downward heat flow and requiring an air space next to the reflective side. Reflective systems are usually located between roof rafters, floor joists, or wall studs. Reflective insulation placed in walls or on the attic floor must be perforated to allow water vapor to pass through it.

Roofing is more than shingles, tile, or metal. A roof system consists of several components, properly assembled to provide the appropriate shelter for a structure. These include structural elements, moisture barriers, and possibly insulation or ventilation.

“Ventilation” is “the natural or mechanical process of supplying conditioned or unconditioned air to, or removing air from, any space.” “Infiltration” is the uncontrolled leakage of air through cracks and gaps in the building envelope, especially around windows and doors. Infiltration deals with uncontrolled situations. In our homes we want to be able to control air movement.

The whole-house systems approach looks at the entire house as an energy system with interdependent parts. Like a human body, when one part functions poorly it affects the performance of the entire system. For instance, the benefits of an energy-efficient air conditioner are lessened when a duct system leaks, windows don’t close tightly, the attic is uninsulated, and humid summer breezes are drifting in under the door.