What is EER?
"The Energy Efficiency Ratio (EER) indicates the cooling efficiency of an air conditioner or heat pump," said Richard B. Hayter, director of Engineering Extension at Kansas State University
EER is a measure of the average cooling delivered to the home(Btu) for each unit of electricity used (watts).
The Seasonal Energy Efficiency Ratio {SEER} is similar to EER except that it indicates the efficiency of an air conditioner or heat pump throughout an entire cooling season.
"With either rating system, a higher number indicates greater efficiency," Hayter explained.
The Kansas Corporation Commission requires an EER or SEER of at least eight for air conditioners rated at 65,000 BTU per hour or less in new residential and commercial installation before a permanent electrical connection can be made to the building- The typical residential central air conditioners range between 30,000 and 54,000 BTU per hour.
The minimum EER or SEER for heat pumps is 7-5.
"Considerably higher efficiencies are available, and should be considered when purchasing a central air conditioner or heat pump," Hayter said.
Does the color of my roof affect the cost of cooling my home?
"Because dark colors absorb heat and light colors reflect heat, roof color can affect the temperatures of spaces-adjacent to or near the roof," said Bruce Snead, extension specialist in residential energy at Kansas State University.
As the roof becomes hotter, radiant and convective heat gain on the attic and ceiling increases, raising the demand for cooling in the spaces below these areas.
Attics, cathedral ceiling spaces, and second floor rooms may be most susceptible to roof temperatures. Attic and wall insulation should significantly reduce interior heat gain caused by a hot roof.
"Proper ventilation also will help prevent heat buildup by drawing in outside air to cool the attic," Snead said.
Where the roof is exposed to the sun during the summer, using light-colored roofing material will further reduce heat gains.
"Certain roofing materials are 'cooler' than others." Snead said. "Wood shakes and shingles are most effective. followed by tiles and light-colored asphalt shingles."
Tarred roofs, asphalt roll roofing and metal roofs are among the hotter roofing materials.
Will adding a device to cycle my air conditioner compressor cause it to run cooler and improve the efficiency?
"Increased cycling of air conditioning compressors can cause three problems," said Dennis Matteson, extension specialist at Kansas State University.
First, increased compressor cycling may increase the humidity of the air conditioned space. During the time the compressor is cycled off and the fan is still operating, the moisture from the cooling coil will be carried back into the conditioned space.
Second, the life of the compressor may be shortened. The cycling time of the compressor will vary from short on and long off periods during moderate weather to almost continuous operation in the hottest weather. This type of cycling in designed into the controls and is necessary to match the capacity to the cooling load. Increased cycling of the compressor often during hot weather increases wear and can reduce compressor life.
Third, the cooling capacity will be decreased. If the system is sized properly and you add a cycling device, during the hottest weather the reduction in cooling capacity caused by the cycling will cause the comfort to suffer.
"The main difference between the air conditioner cycling due to the thermostat and adding a cycling device is the rate of cycling," Matteson said. "Thermostat cycling is designed with a long enough delay to avoid damaging the compressor."
Can you provide some suggestions for saving energy around the house that won't cost much?
"You can take the following measures for very little expense," said Tom Logan, energy specialist with Engineering Extension at Kansas State University:
"If the fan operates after the compressor turns off, then moisture which has condensed on the coils is blown back into the house. This adds to the air conditioner cooling load."
Moreover, Matteson said, a motor that runs part time costs less to operate than one operating continuously.
"For instance, the cost of continuously operating a 1/3-horsepower motor, is about $25 per month at seven cents per kilowatt hour. If you system normally operates 50 percent of the time and uses a 1/3-horsepower motor on the fan, you would save $12 a month by setting it in the automatic mode."
I'm shopping for a new gas furnace. How can I tell which models are most energy efficient?
The efficiency of new combustion furnaces is rated in percentages called Annual Fuel Utilization Efficiency {AFUE}.
"The higher a unit's AFUE, the more efficient the unit is," said Tom Logan, energy specialist at Engineering Extension, Kansas State University.
Although no combustion furnace can extract all of the energy available from the fuel it burns, the AFUE indicates how much available energy the furnace can be expected to deliver through a typical heating season.
Many existing "Conventional forced air furnaces usually range between 60 to 75 percent efficient," Logan said. "That is, 60 to 75 percent of the energy in the fuel goes toward heating the home and the rest is lost up the chimney or goes to replace heat lost from the house through the furnace and flue." The minimum efficiency currently available is about 80%.
This was the result of energy efficiency legislation passed in 1987 by congress.
Pulse combustion furnaces may reach efficiencies as high as 96 percent. A furnace with an AFUE of 96 percent needs only about two thirds as much fuel as a unit with an AFUE of 6O percent to deliver the same amount of heat, according to Logan.
Heating equipment dealers should have the ratings available for the models they sell.
In new home construction, how should I insulate a four- to six-inch thick concrete slab type of floor?
"A concrete slab floor should be insulated first at the edge of the slab where it is exposed to the outdoor air and then down the face to the frost line or below," said Bruce Snead, extension specialist in residential energy at Kansas State University.
A foam board type of insulation is most suitable, usually extruded polystyrene with enough thickness to achieve at least an R-value of 12.5.
"Insulating beneath the floor depends on a number of factor," Snead said. "If the slab is to be covered with carpet or other insulating materials, you don't need insulation underneath."
You should definitely insulate the slab if you have any buried or in-slab heating systems. If the slab area is small or is exposed on two or more sides, insulating the sides and underneath will tend to keep the slab warmer.
If the slab is to be used for direct-gain passive solar storage, insulation will reduce the heat loss to the earth below and keep the floor more comfortable. Insulate wherever the sun will strike the floor and where desired for comfort.
In larger slabs, a four-foot-wide band of insulation near the edge may be sufficient.
"If the slab rests on damp or wet soil, it will tend to lose heat more rapidly and insulation will help retard this loss," Snead said. In general, a one-inch thickness of extruded polystyrene should be adequate for most installations."
What does the term "slab heating " mean?
"Slab heating is a method of distributing heat through concrete floors," said Doug Walter, extension specialist in residential energy at Kansas State University.
Electrical coils or, more typically, hot water pipes buried in the concrete when it is poured, supply or distribute the heat. The floor becomes warm, but not hot, according to Walter.
"This kind of heating is very comfortable, without drafts or cold spots," he said. "The concrete mass moderates the temperature for a stable, even heat output."
However, slab heating has disadvantages. It is generally feasible only in new construction and may have a substantially higher initial cost than more conventional forms of heating, especially if a ducted forced air system is installed to provide air conditioning. And during extremely cold weather, a slab heating system may not be able to supply enough heat to keep a house comfortably warm because of the need to keep the temperature of the concrete slab below skin temperature.
Why does my refrigerator run all the time?
"Your refrigerator may be working overtime if the thermostat is set too low, if family members open the door frequently, or if the seal around the door isn't tight," said Dennis Matteson, extension specialist in small business energy at Kansas State University.
Matteson also recommends that homeowners check the condenser coils located on the back or under the refrigerator.
"Look for dirt and lint in the condenser coils," Matteson said. "Be careful not to bend or poke the coils with sharp objects."
Usually blowing the coils out with air or a soft brush is the best methods of cleaning them.
Also, check to see that the air flow across the coils is unobstructed.
If your refrigerator is in an area recessed into cabinets or a wall, it might run excessively because the heat cannot get away.
If the coils are clean and air circulation is not obstructed, you may need to consult a maintenance person if you think your refrigerator is running excessively.
The size of air conditioners is often expressed in "tons." What is a ton of air conditioning, and why is it called that?
"The size of an air conditioner indicates how fast the unit removes heat from a building," said Tom Logan, energy specialist at Kansas State University. "A one-ton air conditioner removes 12,000 Btu of heat per hour."
A ton of air conditioning removes the amount of heat required to melt 2,000 pounds, or one ton, of ice in 24 hours. Typical residential central air conditioners in Kansas range between one and a half to three tons.
"The proper size for a particular home can be estimated from the home's construction, materials, age, size and orientation." Logan said. The amount of air conditioning required for a home should always be calculated. Square feet per ton are useful for estimating equipment sizes, but do not take into account the variables of shading, insulation, construction, windows, height of the home.