Ask Energenie

January 1999

Table of Contents

1. How do the refrigerants in my air conditioner affect the ozone layer?
2. Why put radon detectors in the basement?
3. In a past column, you recommended installing a continuous plastic vapor barrier behind the drywall in new construction. I've heard some people say this shouldn't be done because it makes walls "sweat." Is this true?
4. Where in the basement are the best places for placing a radon test kit?
5. Can I close some of my attic vents during the winter?
6. Everything I’ve read tells me I’m supposed to test for radon in my basement. What if I don't spend any time in my basement?
7. Will my gasoline line freeze due to the wind chill created by driving faster?
8. I am thinking of installing an air-source heat pump system in my home. What is the advantage of using a heat pump system versus a conventional electric resistance system, and what are the basic types of heat pump systems?
9. Please provide information regarding indoor air pollution and methods for controlling it.

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1. How do the refrigerants used in my air conditioner affect the ozone layer?

"Some refrigerants contain chlorofluorocarbons (CFCs), but not all have the same effect on the ozone layer," said Richard B. Hayter, director of Engineering Extension at Kansas State University.

"The refrigerant once used in automotive air conditioners, refrigerators and large air conditioners used a stable compound, R-12, that did not rapidly decompose when released to the atmosphere," Hayter said. "R-12 and other stable refrigerants containing chlorine are no longer manufactured. However, equipment that uses R-12 and other ozone-depleting refrigerants are still in operation."

Conversely, the refrigerant used in small air conditioners (such as your home unit) uses either the relatively unstable compound R-22 or other refrigerants which either do not damage the ozone layer or have a lower potential to do so.

When R-12 and other stable, chlorine-containing refrigerants were released to the atmosphere either by accident or deliberately, they rose to the stratosphere where ultraviolet radiation ultimately broke them down, releasing chlorine. These chlorine atoms then combined with the ozone and broke it down.

"The unstable refrigerant used in some air conditioners (R-22) has less effect on the ozone layer. This is because it breaks down in our lower atmosphere before the chlorine atoms reach the ozone," Hayter said. "Some of the newer refrigerants have no ozone depleting chemicals."

Chemical manufacturers have developed substitute refrigerants that minimize the effect on the ozone layer. Similarly, equipment manufacturers sell equipment specifically for use with these new refrigerants. Because of new designs, many times the efficiency of the new equipment is considerably higher than the older refrigeration and air-conditioning equipment.

"Regardless of the refrigerant used, we must recycle existing refrigerants as air-conditioning equipment is serviced rather than vent them to the atmosphere," Hayter said.

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2. Why put radon detectors in the basement?

"The primary source of radon in the environment is the naturally-occurring uranium and radium present in the soil underneath and around our house foundations," said Bruce Snead, extension specialist in residential energy at Kansas State University.

The basement, being usually the lowest lived-in level and closest to the source of radon, is an appropriate place to test, especially if there are bedrooms or other living spaces on that level.

"You can conduct the tests on any level of your home, but testing in a livable area of the basement helps to establish the potential for elevated radon that may exist throughout the house," Snead said. "Testing in the lowest livable level and in spaces where you spend the most time indoors (such as bedrooms) can help you understand your exposure and the typical levels in your home."

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3. In a past column, you recommended installing a continuous plastic vapor barrier behind the drywall in new construction. I've heard some people say this shouldn't be done because it makes walls "sweat." Is this true?

"No, but it's easy to confuse the installation of vapor barriers with moisture problems because vapor barriers do affect indoor relative humidity," said Doug Walter, president of Kansas Building Science Institute, Manhattan.

The purpose of a continuous vapor barrier is to prevent moisture from entering wall cavities and attics, where it can condense on cold surfaces and cause structural damage.

The vapor barrier also reduces air leakage. Moisture produced by household activities accumulates more quickly because of the reduced airflow, resulting in a higher relative humidity. If the humidity gets high enough, windows and other cold surfaces begin to "sweat," or condense moisture.

"Condensation problems can be especially severe during a new home's first winter," Walter said. "This is due to extra moisture stored in drywall from joint compound and paint."

Use of exhaust fans during periods of peak moisture production, such as while showering, bathing, cooking and wet cleaning can prevent or control moisture problems.

"Your construction-related moisture problems will diminish with time as finish coatings cure," Walter said. "However, additional ventilation may be necessary during your new home's first winter."

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4. Where in the basement are the best places for placing a radon test kit?

"Place it in a bedroom, family room or other living area, according to the instructions with the test kit," said Bruce Snead, extension specialist in residential energy at Kansas State University. "Keep it off the floor, away from heat and away from drafts and windows. Put it in a location where it will be exposed to the typical conditions of the room."

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5. Can I close some of my attic vents during the winter?

"Yes. But, assuming that your attic is properly insulated, there isn't much advantage in closing the vents in winter," said Gene Meyer, extension mechanical engineer at Kansas State University.

"Because insulation is typically in the floor of the attic, the attic temperature will be close to that of the outdoor surroundings," he said. "Closing some vents won't significantly change this temperature."

An attic requires a certain amount of ventilation during the winter for moisture removal. This ventilation area is about half that required during the summer.

"Your attic will require more ventilation if significant moisture sources exist. Such moisture sources would include kitchen or bathroom vents," Meyer said.

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6. Everything I’ve read tells me I’m supposed to test for radon in my basement. What if I don't spend any time in my basement?

"Then you get your exposure in other locations in the home and testing there would be appropriate," said Bruce Snead, extension specialist in residential energy at Kansas State University. "Bedrooms are good locations for testing because that's where we typically spend the most time in a home."

The reasons to test in the basement include proximity to the source in the soil, living patterns and primarily because it is a good indicator of the potential for radon levels throughout the home.

Professional testers and those involved in real estate transactions will want to test in the basement, or lowest livable level of your home for a variety of reasons related to liability, repeatability and reliability of the results, Snead said.

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7. Will my gasoline line freeze due to the wind chill created by driving faster?

"No, because the speed of the air cannot cause fuel to be colder than the air temperature," said Richard B. Hayter, director of Engineering Extension at Kansas State University. "An increase in wind velocity can speed up heat loss between warm objects and cooler air, but since the fuel tank is already at ambient temperature (equal to surrounding temperature), wind velocity will have minimal effect."

Wind chill is the sensation caused by cold air moving across the skin. The wind chill equivalent is the temperature of still air that causes the same sensation as moving air does at a higher (not lower?) temperature.

"When selecting your clothing, always consider wind chill." Hayter said. "Your body loses heat at a higher rate when exposed to wind. Multiple layers of clothing provide the best insulation value, but be sure to select materials that block air flow."

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8. I am thinking of installing an air-source heat pump system in my home. What is the advantage of using a heat pump system versus a conventional electric resistance system, and what are the basic types of heat pump systems?

"The chief advantage of using a heat pump over an electric resistance system is it is more cost effective than conventional electric resistance heating," said Richard Nelson, extension specialist in energy at Kansas State University.

"In most cases a heat pump can provide heat at one-half to one-third the cost of electric resistance heating," Nelson said. "The reason for this savings is that a heat pump uses available heat from the environment rather than creating it."

The basic types of heat pumps on today’s residential market are air-source and water-source. Air-source heat pumps extract heat from the outside during the heating mode and deliver it to home interior. During the cooling mode, the heat pump acts just like an air conditioner, removing heat from inside and dumping it to the outside.

Water-source heat pumps work in a similar fashion, only water is the heat source or sink. Water, either from a well or circulated through pipes buried in the ground, is pumped to the heat pump where heat is either extracted (heating mode) or dumped (cooling mode). In the heating mode, the extracted heat is delivered to the house. In the cooling mode, heat is removed from the house.

"The majority of residential heat pumps are air-source," Nelson said. "However, the higher initial cost of water-source heat pumps is often offset by their higher efficiency. As a result, they are gaining popularity."

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9. Please provide information regarding indoor air pollution and methods for controlling it.

"Indoor air pollution is the presence of contaminants in air that causes short- and long-term health problems," said Richard B. Hayter, director of Engineering Extension at Kansas State University. "Pollutants may exist as gases or particulates and may be pathogenic (disease causing) such as bacteria or viruses, or may cause a body reaction."

Pathogens may be brought indoors from outdoor air, as might be the case with Legionella bacteria producing Legionnaires Disease. Pathogens may also be introduced by individuals or animals within the space or food that is present. The pathogen may directly affect the occupants of the space or may continue to breed in damp wall and roof insulation, or areas of stagnant water such as reservoir-type humidifiers that have been inactive.

"To minimize this type of indoor air pollution, practice proper maintenance of equipment, including chemically treating the water in evaporative condensers used by commercial buildings, cleaning and drying humidifiers when not in use, and maintaining roofs and installing vapor barriers," Hayter said.

Improper equipment operation, certain building materials and building maintenance can also cause indoor air pollution. For example, poorly ventilated combustion devices may be subject to back drafting (the flow of exhaust gases back into occupied space rather than out the flue) and could introduce carbon monoxide into the space.

Building materials may pollute indoor air if they contain high levels of formaldehyde, which is released as the materials cure.

"Some people are allergic to formaldehyde, so reduce the risk of complications by properly ventilating materials during curing," Hayter said.

As for building upkeep, poorly maintained filtration devices may allow particulates to remain in occupied space, causing a reaction by the occupants. Mechanical filtration as well as electronic filters must be regularly cleaned or replaced.

Another indoor air pollutant is that produced by some cleaning agents and solvents. Some individuals are sensitive to fumes produced by these chemicals and will suffer respiratory disorders and eye irritation.

"Numerous other pollutants may exist in an indoor environment," Hayter said. "To control them, building operators must first try to prevent them from entering a building. Proper maintenance of equipment and sufficient ventilation correctly distributed within each occupied space will control those pollutants that already exist."

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Ask Energenie is produced by the Kansas Energy Extension Service through Kansas State University. This material was prepared with the support of the U.S. Department of Energy (DOE) Grant No. DE-FG47-92-CE60210. However, any opinions, findings, conclusions, or recommendations expressed herein are those of the author(s) and do not necessarily reflect the view of DOE.