When Your Home Ceiling Fan Can Save Energy

QUESTION: Does a ceiling fan save energy? We are buying a home with a cathedral ceiling and wonder if a ceiling fan would keep some of the warm air from rising and also help circulate air into the adjacent open space on the second floor.

ANSWER: A ceiling fan can reduce air stratification in a room by circulating air between the ceiling and the floor. It will save energy only if there is a big temperature difference between the floor and ceiling. Not all houses or rooms with cathedral ceilings have high stratification levels. You should check air temperature differences before you buy. A 10-degree Fahrenheit difference or more may make it worth considering.

A high degree of stratification means the average temperature of the space is higher than the setting on your thermostat. By using a ceiling fan to destratify the air, the average temperature of the space is lowered while still satisfying the same comfort set point of your thermostat. A lower average temperature will require less from your furnace (even though the thermostat is set the same).

The type of heating system as well as other factors can have an effect on stratification. For example, heating systems that supply heat at floor levels may not result in stratification. As the warm air rises, it loses its heat and therefore disperses; resulting in fairly even floor/ceiling temperatures. A ceiling fan will offer little in such a case.

The type of heating system, the furnace fan speed, the location of return air grills, air infiltration, use of a wood stove, and shape of the space will also affect stratification. It is difficult to predict which conditions will actually produce stratification or what effect a combination of conditions would have in any particular case. Again, the best way is to actually measure the temperature difference under typical conditions.

A ceiling fan may also help circulate air to your adjacent second floor space. How well it does this depends on the specific air flow pattern the ceiling fan sets up, the speed of the fan, and the configuration of the space. A fan on high speed may produce unwanted drafts. It would be difficult to predict the circulation pattern that would result.

Why you would want or need to circulate air to the adjacent open space may depend on a couple of conditions. If the space is not heated, it may not need more air circulation to maintain a reasonable temperature. If it is heated, it shouldn’t need it either. For air circulation to occur effectively, the ceiling between the two would probably have to be free of obstructions (e.g., beam or partial wall) and the space would have to have a place for air to circulate back to other areas of the house.

There are also other methods than ceiling fans that can be used to destratify the air. One method uses a small high speed fan hung from the ceiling that circulates air at high velocities from the ceiling toward the floor. Another method can be constructed using supply and return registers near the floor and ceiling, ductwork and a fan to circulate air. These methods help remove warm air at the ceiling level and circulate it to the floor level. This mixes the air better for more even floor/ceiling temperatures.

Fluorescent Lights Brighter, Cheaper

Q: Why would I buy expensive compact fluorescent lights when there are little buttons that can be put in existing lamp sockets that do the same thing for a lot less money?

A: The “little buttons” you refer to are probably devices intended to reduce your voltage. They will indeed reduce electrical consumption and increase bulb life, but the price paid is decreased light. Lowering the voltage reduces the temperature the filament in the bulb is heated to, causing less light to be produced. About 90% of the electricity used by an incandescent bulb is turned into heat, only 10% is given off as visible light.

Compact fluorescents produce about the same amount of light as an incandescent bulb, but use about one-fourth the energy.

Battery Can Silence Smoke Detector Beep

Q: The smoke detector in my home is wired into the house circuit. It has been making intermittent beeps. . . . I was told that it needs a new battery. Is this true of a wired-in detector?

Looking through the sides it seems as if there is a place for a battery, but I cannot discover how to get the detector apart to determine if there is a battery inside or not. Does the detector need a battery or do I need a new smoke detector?

A: Smoke detectors that are wired into the house circuits often have a battery back-up so that they are still functional in the event of an electrical power outage. The beeps may be telling you that either the back-up battery needs to be replaced or the sensor or circuitry in the unit is faulty.

To find out, remove the cover to determine if there is a battery in place. If you cannot locate the manufacturer’s instructions for the unit or figure out how to remove the cover after close inspection, contact your local fire department for assistance.

If you find a back-up battery in the unit, simply replace it with a fresh one. Replace the cover and test it (read on for a description of simple test procedures). If the unit does not pass the test, or if the beeping continues, check for a burned-out bulb in the detector. Replace the bulb and test the detector. If the detector still does not pass the test, replace the detector with a new one immediately. Purchase a good quality unit and have a licensed electrician do the installation.

Most fire professionals recommend having at least two smoke detectors in your home: one ionization type and one photoelectric type. The ionization detector detects very small smoke particles that are usually associated with hot, blazing fires (such as a smoky fireplace). Photoelectric units detect larger smoke particles associated with smoldering fires (such as the burning of overstuffed furniture). While both types are effective, having both in your home helps assure that you will have early warning of either type of fire.

You should test your smoke detectors once a month. If you’re testing an ionization detector, hold a burning candle flame 6 inches below the detector. To test a photoelectric unit, extinguish the candle and let visible smoke drift into the detector (heavy tobacco smoke will also work). Both units should sound the alarm by 20 seconds. The alarm should cease soon after you fan the smoke away or remove the flame from under the detector.

It is good practice to keep handy a spare batbattery and bulbs for photoelectric units for immediate replacement.

Reduce your risk of having a fire by having your fireplace and/or wood stove flue cleaned on a regular basis . . . the frequency of cleaning depends on the amount of time they are used, how they are operated and the type of fuel used.

Have electric, gas, and oil furnaces checked by a professional once a year to ensure that they are operating properly. This can save you money on your energy bills and at the same time help prevent a disastrous fire. Use portable heaters safely. Keep away from furniture and drapes. Never operate while gone from the room or asleep.

Radiation From Smoke Detector Not Harmful

Q: A while ago I clipped a piece about smoke detectors. My questions regard the radioactive material in the detectors on the market. Is there credible independent documentation that this material is not harmful in a household situation, over a long exposure?

A: The smoke detector you’re referring to is an ionization model that contains a small amount of radioactive material. The particles (alpha) travel very short distances--so when the detector is mounted on the ceiling people are not in its radiation zone.

According to the U.S. Nuclear Regulatory Commission, the radiation produced by these detectors is not a hazard. If you held an ionization smoke detector close to you for eight hours a day for a year, you would receive only 1/10th as much radiation as you’d get on one round trip flight across the United States.

There is another type of smoke detector with no radioactive material, called a photoelectric model. It’s equipped with a light and photocell, which sees particles. Because smoke has different characteristics (i.e., particle size, velocity) depending on the type of fire from which it is generated, the photoelectric and ionization detectors respond to it differently.

Photoelectric detectors are slightly more effective at detecting larger particles--these emanate from cool, smoldering fires, such as the burning of overstuffed furniture. Ionization detectors are slightly more effective at detecting smaller particles--these may emanate from open, flaming fires.

Sometimes a smoky fireplace or burned toast will trigger an ionization model. If you choose an ionization model for the choose an ionization model for the kitchen, be aware that the incidence of false alarms could be high. A better choice might be the photoelectric model.

Some smoke detector manufacturers have developed a detector that combines ionization and photoelectric systems in one unit. Note that these detectors have a higher incidence of false alarms than the single units.

You can also call the U.S. Consumer Product Safety Commission (1-800-638-2772) for more written information including product recalls.

Shopping for Smoke Detector You’ll discover a wide selection at your hardware, department, building supply, or discount store. It’s a good idea to look for one that has been tested and certified by a recognized testing organization. Otherwise, you can’t be sure that the detector model meets minimum performance standards.

Next, look at the instructions. Ask yourself these questions:

1. Are the directions clear and complete? They should tell you how to install it, suggest where to put it, and provide guidance for testing and maintenance.

2. Can you do the installation yourself--safely? Is there a step-by-step explanation, with enough diagrams to tell you exactly what you’ll need to do? This is a good time to decide if you should do the installation yourself. If you don’t feel confident on a stepladder, for example, you may want to ask a friend, relative or carpenter to do it for you.

3. What maintenance is required? Do the instructions tell you how to test and clean the unit, and how often? If the unit uses batteries or replacement lamps, is there a readily visible or audible signal to tell you when replacement is necessary? Ask the clerk if the store carries whatever parts may be needed.

SOURCE: U.S. Consumer Product Safety Commission

Produced by the Energy Extension Service, a division of the Washington State Energy Office.