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Radiant cooling is the opposite of radiant heating.
"An example of radiant heating is to sit near a camp fire in a cool evening," said Richard B. Hayter, director of Engineering Extension at Kansas State University. "Although the air temperature is low, an individual can keep warm by the heat radiated from the fire.
"Conversely, an individual may be uncomfortably cool in a heated room during the winter if seated near a cold window," he said. "In this case, the person is radiating energy to the cold surface of the window, losing heat at a rate faster than if they were not exposed to the cold window surface."
Radiant cooling uses a similar principle, Hayter said. Air temperature in a room is maintained higher than would be considered comfortable normally. Comfort is then provided by cooling one or more large surfaces in the room such as the ceiling, typically by a series of cold water coils embedded in the ceiling.
"With such a system, humidity levels must be controlled to prevent condensation on the cooling panels," he said.
"In some instances radiant cooling can provide comfort at a lower energy cost than a system that depends entirely on air temperature for cooling," Hayter said.
"Cleaning the inside of ductwork will provide only insignificant gains in efficiency," said Bruce Snead, extension specialist in residential energy at Kansas State University.
"Unless there is insulation or debris blocking a duct, simply cleaning the inside of the ducts is not worthwhile," he said.
A homeowner can perform much of the typical cleaning necessary to keep a heating and air conditioning system operating properly.
"Keeping supply and return air registers clean, and changing air filters regularly are two easy tasks that reduce debris built-up in the ductwork," Snead said. "Another cost effective measure is cleaning the furnace fan blades."
Older air conditioning systems also may benefit from cleaning the evaporator coils, usually located above the furnace, he said.
"Money spent on ductwork cleaning would be more productively spent on other energy conservation measures," Snead said.
"In simplistic terms, PVs or photovoltaics are solid-state devices that convert sunlight into direct current (dc) electricity," said Richard Nelson, extension specialist in energy at Kansas State University.
Photovoltaics have been used since the 1950s when they powered satellites in orbit, which they continue to do today.
"PVs are environmentally-friendly in that they do not produce any pollution or emissions," Nelson said. "They contain no moving parts, are noise free and require hardly any maintenance or operational expense over their lifetime of use. PV systems typically last 20 years."
PVs are most cost effective in situations where extending a utility line to the point of application is prohibitively expensive or where the power source needs to be mobile.
"Electrical line extensions can cost a utility anywhere from $5,000 to $25,000 per mile depending on the location of the application and the type of line needed," Nelson said. "In these cases, use of PVs to provide power has been shown to be a cost effective option."
Photovoltaics are manufactured from silicon (sand) and assembled into round or square wafers called cells. These cells are grouped and wired together to form modules or panels. Depending upon the amount of power needed for a particular application, these panels can be further grouped together into arrays.
In some applications, alternating current (AC) is required (household appliances, for example) and in these cases, the direct current (DC) output from the array is converted into alternating current by use of an inverter.
"Some PV applications require energy to be available at night or when it’s cloudy," Nelson said. "In these cases batteries are used to store electricity generated during daylight hours."
There are two types of uses for PVs: stand-alone and utility grid connected. Stand-alone systems are those not connected to the utility grid and independently provide power to a particular application.
Utility grid-connected systems are those that feed the power they generate directly to the utility grid while the utility provides the remainder. Stand-alone systems are used much more frequently than utility grid-connected ones.
"PVs are more common in the southern portion of the United States, but are currently being used throughout the country," Nelson said. "Homeowners, transportation departments, municipalities, rural electric cooperatives and major utilities are using PVs."
Some common applications for photovoltaics include lighting for pathway security and traffic hazard signs, water pumping for livestock, water flow metering, park irrigation, remote weather data collection, school zone flashers and emergency call boxes along highways.
"Probably the one disadvantage associated with PV systems is their high initial cost," Nelson said. "However, when considering their low operational and maintenance costs, plus the fact that they use a ‘free’ fuel source (the sun), the total cost associated with supplying power with a PV system over a period of 20 years may be less than conventional power sources such as diesel fuel generators or electricity."
PVs are most effective in situations where cost prohibits extending a utility line to where the electricity is needed or when the power source needs to be mobile.
"Halogen lamps have a longer life, better color rendition, and the light output does not depreciate with lamp age," said Gene Meyer, extension mechanical engineer at Kansas State University.
Traditional incandescent lamps darken with age. Halogen lamps employ a special gas mixture, higher temperatures and special glass to improve lamp life and eliminate lamp darkening.
"In addition to longer life, halogen lamps offer very clean, bright white light, especially useful for retail display," Meyer said. "The lamps are also used in reading lamps or other applications where light quality is important. "However, halogen lamps that do not have a second glass envelope that limits bulb surface temperature should be used with extreme caution. Bulb surface temperatures of up to 1,100 degrees F are possible.
Some halogen lamps are slightly more energy efficient than regular incandescent lamps. "However, if lower operating costs are your motive, consider using compact fluorescent lamps," Meyer said.
Halogen torchieres are a class of halogen lamps that have gained popularity in the last few years. They often look like a streamlined bird bath on a six foot pole. This class of halogen lamp is less efficient than incandescent lamps and presents a safety hazard because of the high bulb surface temperature.
Several manufacturers have announced plans for an energy efficient torchiere. Contact EPA Energy Star at 202-233-9841 for a list.
"The color of the roof has little effect on heat loss in the winter, but a dark roof can add significantly to heat gain in the summer," said Doug Walter, president of Kansas Building Science Institute, Manhattan.
The total heat gain through a ceiling with R-38 insulation, even with a well-ventilated attic, will be about 20 percent higher if the roof is dark-colored rather than light. With R-l9 attic insulation, heat gain will be 35 percent higher.
"Dark roofs also tend to age faster, due to greater expansion and contraction and thermal degradation," Walter said.
"Only if the fan delivers fresh air to or exhausts air from the kitchen. Ventilation and circulation are two distinct functions, though fans are used to accomplish both," said Dennis Matteson, extension specialist in small business energy at Kansas State University.
"Ventilation requires bringing new air into an area and exhausting the air from that area. This is best accomplished by a fan in a window or ceiling," Matteson said.
Exhaust fans located above the stove are often used to ventilate the kitchen. Moisture, smoke and odors released during cooking can be vented to the outside. However, some above-stove fans circulate the air through a filter, removing grease, and then exhaust the air back into the kitchen. These do not help remove odors or moisture and do not help ventilation.
The most common type of large ventilation fan is the whole house fan. This type of fan is usually located in the ceiling of a hallway. The fan draws fresh air in through windows opened in the rooms needing ventilation.
Ceiling or oscillating fans are used to circulate the air within a closed area. Moving air causes a cooling effect on occupants, providing more comfort at higher temperatures.
"One of the least costly methods of cooling is to use a combination of circulating and ventilating fans rather than air conditioning," Matteson said.
"If the wrap around the insulation has not been damaged and is not in a location where it would be vulnerable to tearing, perhaps you should do nothing because the potential health hazard is minimal," said Richard B. Hayter, director of Engineering Extension at Kansas State University.
"However, if the insulation is damaged and there is likelihood that the insulation will release dust or fibers, it is appropriate to take protective measures," Hayter said.
Experts currently recommend leaving the insulation in place and repairing the protective covering. It may be possible to use a wide duct tape or other commercial product to cover the exposed insulation.
"Homeowners should get professional help to handle materials containing asbestos if they decide to remove insulation from ducts," Hayter said.
The Kansas Department of Health and Environment can provide information on testing material for its asbestos content as well as appropriate techniques for handling asbestos.
For information, contact Gary Miller at Kansas Department of Health and Environment, Forbes Field, Topeka, Kansas 66620-7430, or call him at 785-296-1547.
"You’ll want the highest U-value you can get for what your budget allows," said Gene Meyer, extension mechanical engineer at Kansas State University (KSU).
U-values are a measure of how much heat is lost through the window and frame.
"Window frames are manufactured from different materials (wood, plastic, metal); have one, two or three glass layers, use special and light-reflecting films, and use air or special gas fillings between glass panes," Meyer said. "The possible combinations number into the hundreds."
"Fortunately for consumers, the National Fenestration Rating Council now publishes its Certified Products Directory that lists U-values for windows," he said.
The catalog rates the performance of windows in the way other catalogs rate that of heating or cooling equipment.
"The Certified Products Directory allows comparisons of specific models from several manufacturers," Meyer said. "We use a copy of the rating book here at Engineering Extension to help consumers."
Detailed rating information is also attached to new windows on a temporary label. This label is designed to provide consumers, builders and code officials with energy performance information in a comparable, easy-to-read format. The temporary label is accompanied by a permanent label or marking somewhere on the product, usually in an area that is unseen when the window is closed.
Pricing information is available from suppliers, Meyer said.
"The location of the moisture can be an indication of a failed seal," said Dennis Matteson, extension mechanical engineer at Kansas State University.
"In a sealed double-pane window, the space between the double panes is filled with a dry gas and may contain a desiccant, a material which absorbs moisture," he said.
If the moisture is between the two layers of glass, the seal has failed.
"Contact your window supplier to determine if there is a way to fix the problem," Matteson said.
If the moisture can be wiped from the room-side surface of the inner pane, the moisture is condensing from the room. On a double-pane window this is an indication of high humidity and does not indicate a failed seal.
"To avoid having moisture condense on the inside of the window, you have to remove moisture from inside the building," Matteson said. "You can do this usually by using exhaust fans in kitchens and bathrooms."