Heat pumps are far more energy efficient than electric resistance heat and can be used for both heating and cooling. Heat pumps extract heat from outside air or, in some cases, from a water source. Air-source heat pumps are most common in areas where winter temperatures seldom fall below 30 degrees Fahrenheit and where summer cooling loads are high. As temperatures fall below 30 degrees, the heat pump must rely on electric resistance heating to make up the difference, at which point the system loses its economic advantage. Tire main advantages of a heat pump are that heating and cooling needs are met by a single unit, humidity is not added to the air, and operation is quiet.
Common types of air conditioners include condensing or refrigerated air conditioners, electric heat pumps as discussed above, and evaporative coolers.
Condensing air conditioners are available either as small units designed to cool one area of a home or as central air conditioners, which will cool an entire home via ductwork. Advantages of central air conditioners are their out-of-the-way location, quiet operation, integration with the forced-air heating system, and greater cooling capacity and efficiency than portable models. However, these central systems consume a lot of energy and cost up to seven times more to operate than evaporative cooling systems. It is important to choose an air conditioning unit that continues to blow air across the cooling coils for a time after the cooler is turned off. This allows any moisture remaining on the coils to be dried off, discouraging mold growth. Room air conditioners are less expensive to install than central air conditioners. Since they cool only designated areas, they save money and energy, but they do tend to be noisy.
Evaporative coolers are practical in very dry areas and are available either as a direct model, which adds humidity to the home, or an indirect model, which does not add humidity. The operating costs for evaporative coolers are significantly lower than those for condensing units, and evaporative units are fairly inexpensive to install. They bring fresh outdoor air into the living space and exhaust stale air. Evaporative coolers have a lower cooling capacity and work well only in low-humidity conditions, such as those found in the southwestern states. Another name for evaporative coolers is swamp coolers. They must be kept clean or they truly become swamps, filled with microorganisms.
When using mechanical air conditioning, you can save energy and money by keeping the windows closed. One exception to this rule is the case of evaporative coolers, which are more efficient when windows are left partially open. Air conditioners should be shut off and windows opened at night if it is cool outside. Do not cool unoccupied rooms or homes. Insulating all exterior ducting can save you at least 10 percent of the energy costs of
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Type of system |
How it works |
Advantages |
Disadvantages |
Comments |
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Heating Systems |
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Forced air heat |
A fan pulls air through a heating unit and distributes the air throughout the house via ducts. |
• Can be easily adapted for filtration, humidification, and dehumidification • Almost immediate response time • Inexpensive to operate |
• Less comfortable than radiant heat • Stirs up and fries dust • Can exacerbate allergies • Ductwork is architecturally cumbersome • Leaky ducts can depressurize home • Noisy • Needs regular cleaning • Metal ductwork grounds negative ions • Fumes from gas or oil fuel can enter airstream — Insulation particles can enter airstream |
• Many of the disadvantages of forced air can be rectified by adding filtration to the system at the furnace and where the air enters the room |
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Radiant hydronic floor heat |
Hot water is run through tubing in or under the floor. Natural convection gently distributes heat. |
• Even, comfortable heating • Comfortable at lower temperatures • Efficient • Not hot enough to fry dust • Silent • Low maintenance • Easyzonation • Invisible |
• Slow response time • Initial installation costly • Does not filter air • Not practical for cooling |
• Avoid metal tubing, which can transmit EMFs |
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Liquid-filled baseboard heaters |
Hot liquid is circulated through fin tube baseboard units and radiates into the room. |
• Heats quickly • Comfortable radiant heat • Not hot enough to fry dust • Less expensive than in-floor heating |
• Baseboard units are dust traps • Limits furniture placement • Can be hot to touch |
• Heated surfaces of baseboard units may outgas • Leaks (other than water) may be toxic |
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Electric radiant floor, wall, or ceiling heat |
Electric current passes through resistant wiring embedded in walls, floors, or ceilings. |
• Even heating • Comfortable radiant heat |
• Expensive to run • Can create high levels of EMFs • Less expensive systems run hotter and fry dust |
• Not recommended in a healthy home because of EMFs and high degree of energy consumption |
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Type of system |
How it works |
Advantages |
Disadvantages |
Comments |
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Electric baseboard heating |
Individual units are plugged in. |
• Initial installation inexpensive and easy • Does not require centralized machinery • Puts heat only where required |
• Expensive to run • Hot to touch ■ Traps and fries dust • Emits EMFs |
* Heated surfaces may offgas |
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Woodburning stoves |
Wood fire is contained in a noncombustible stove. Heat radiates into the room. |
• Radiant heat source • No central equipment required • Inexpensive to install and operate |
• Messy to run and requires high maintenance • Burn and fire hazard • Chimney can be subject to backdrafting • Burning wood produces more than 200 toxic byproducts of combustion and studies show higher rate of respiratory problems in children where woodstoves are the primary heat source • Most heat escapes up the chimney |
• Not recommended in a healthy home * Choose the most efficient models available, burn hardwoods, and clean the flue often |
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Masonry heater (Kachelofen) |
Heat from wood fire travels through a series of masonry chambers, is stored in the masonry mass, and slowly radiates into the room. |
. Very efficient use of fuel • Requires less tending than conventional woodstoves • Burns cleaner • Produces comfortable radiant heat that does not fry dust or burn people • Inexpensive to operate, requires no further equipment • Can incorporate cook — stove or oven • Can be an architectural feature • Short duration of fire time; full combustion of gases creates little pollution inside and outside the home |
• Initial installation is costly • Generates a small amount of combustion byproducts |
• Less convenient than central heating systems • Considered by Bau — Biologie as one of the most healthful ways to heat |
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Type of system |
How it works |
Advantages |
Disadvantages |
Comments |
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Passive solar heating |
Heat from the sun is captured through glazing and stored in building components with high thermal mass such as concrete and adobe walls and floors. |
• No operation expenses • Does not consume fossil fuels • Does not fry or circulate dust |
• Dependent on weather • Requires a relatively high degree of human interaction. • Must be incorporated into architecture |
• For more information, refer to the Further Reading section |
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Heat pump |
Heat or cold is extracted from outside air and transferred to inside air. |
• Can be used for heating or cooling • Cost effective in mild climate • Quiet |
• Not cost effective where temperatures are frequently below 30 degrees F. * Uses Freon (an atmospheric ozone depleted as transfer medium |
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Cooling Systems |
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Central refrigerant coolers |
Freon gas is passed through a condenser. Heat is transferred to the outdoors and the cool air is distributed throughout the house via ductwork. |
• Can also dehumidify air • Will handle large cooling load • Can be quiet to operate if condenser is remote • Shares ductwork with central heating |
* Expensive to operate * High energy consumption • Uses Freon (an atmospheric ozone depleted • Requires maintenance to prevent mold |
• Drip pan must be inspected and cleaned regularly for mold-free operation |
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Room refrigerant coolers |
Freon gas is passed through a condenser. Heat is transferred to the outdoors and the cooled air is blown into the room. |
• Inexpensive initial installation • Because it cools only designated areas, energy waste and expense are reduced |
• High energy consumption • Uses Freon — Requires maintenance to prevent mold • Noisy |
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Evaporative (swamp) coolers |
Air is passed over a wet medium. As evaporation occurs, air is cooled and then blown into the home. |
• Low cost initially and when in operation • Uses no CFCs or HCFCs • Requires 80% less energy than refrigerant coolers • Works well in hot, dry climates |
• Subject to mold and other microorganism growth • Not suitable in humid conditions • Cannot take as large a load as refrigerant models • Can be noisy • Requires maintenance to keep mold-free and needs frost protection in cold winter climates |
• Should be drained and cleaned monthly |
cooling. Maintain systems regularly, keeping coils and filters clean. Locate the cooler in a shaded area.
