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Energy Efficiency for Condominiums: A Guide for Association Officers and Directors

As a condominium board member you have probably been facing the problem of rising utility costs. This guidebook provides measures that your board can find useful in reducing utility costs. The measures listed are not all-inclusive. The guide has been kept short to emphasize items that can make substantial contributions to reducing utility costs.

The suggestions listed are intended to identify energy-saving actions you can take. Detailed information on each suggestion is available from the appropriate contractors, your utility company, and local county extension agents.

Many condominium associations have tried one or more of these recommendations and as a result are already saving energy and money. We hope this guide will help you do the same thing.


Studies show that running an air conditioner only one or two hours per day can control humidity in an unoccupied apartment. The common practice of setting thermostats at 80-820 F to control humidity often results in operating the air conditioner 8 to 1 2 hours daily. If a 2-ton air conditioner runs 1 0 extra hours per day, it will consume up to 1500 unnecessary kilowatt-hours (KWH) per month. At 6 cts per KWH, this adds up to $90 per month to do a job that should cost $9 to $18 per month.

Timers can be set to allow the air conditioner to run only two hours during a predetermined time period, usually 5 to 7 a.m. Humidistats turn on the air conditioner only when the humidity exceeds a predetermined value, usually 60 to 65 percent. Both are available through electrical or air conditioning contractors and can usually be installed for less than $100.


Water-cooled air conditioners frequently use a large pump that circulates water through the units even when the units are not running. If water is shut off when units are idle, a smaller pump can be used to supply water to the operating units.

Solenoid valves can be installed to open when the air conditioner turns on and to close when the air conditioner turns off. The large pump is then replaced by three or four smaller pumps that turn on as needed. Replacing a 40 horsepower pump with smaller pumps can save you more than $600 per month if the average load is 20 horsepower.

If you have water-cooled air conditioners in your building, you will want to ask your contractor for more information on this system.


Many mid-rise and high-rise condominiums are equipped with bathroom and/or kitchen ventilator fans that run 24 hours a day. These fans are usually located on the roof of the building. They look like big metal mushrooms.

When energy was less expensive, these fans provided a convenient means of removing odors. During heating and air conditioning seasons, however, they remove up to 300 KWH per month worth of conditioned air from each apartment. As a result, if electricity costs 6 cts per KWH, each owner pays up to $18 per month in unnecessary costs every month that heating or air conditioning is used.

If part of the air is drawn in from an air-conditioned hallway, then the association pays part of the $18 each month, since hallway air must then be replaced by outside air. When the apartment is unoccupied during the summer months, these fans draw warm, moist air into the apartment through cracks around windows, doors, light switches, and other places.

Recirculating fans that can be operated on demand, or even ventilating fans that can be switched on when needed, can eliminate most or all of the waste of the continuous system.


Fluorescent tubes provide about three times as much light as conventional light bulbs of similar wattage. If your hallway lights burn continuously, you can save one kilowatt hour per month for each 1.4 watts of reduction in power used by lights. You can also achieve measurable savings with incandescent lamps if you use a lower wattage or reduce the hours of operation.

Another factor worth considering for keeping costs down is the maintenance cost of replacing burned out bulbs. Fluorescent lamps last 12,000 hours, or about 15 times longer than the average incandescent lamp.

You might want to appoint a committee to visit a few lighting stores to investigate the recent innovations in fluorescent hallway lighting. Remember that if electricity costs 6 cts per kilowatt hour, you save 4.3 cts each month for every watt you save, if the light is on 24 hours a day.


The efficiency of a light bulb depends on its efficacy. The efficacy relates the amount of light produced (lumens) to the amount of electricity used (watts). Typical lamp efficacies:

bulletIncandescent - 20 lumens/watt


bulletMercury Vapor - 50 lumens/watt


bulletFluorescent - 60 lumens/watt


bulletMetal Halide - 90 lumens/watt


bulletHigh Pressure Sodium - 120 lumens/watt


If you are lighting your outdoor areas with inefficient lamps, you are probably spending up to six times more than is necessary to achieve the desired result. A lighting consultant or lighting engineer can usually assess your potential savings in outdoor lighting expenses.


Building codes require that a small amount of outside air be supplied to public areas in condominiums, but frequently the openings to outside air are much larger than needed. Large amounts of warm, humid air may be brought into the building during the summer months. Every 100 cubic feet per minute (CFM) of air brought into the building can add up to 400 KWH to monthly cooling bills. Since air conditioners usually circulate air at about 400 CFM per ton of air conditioning, a 5-ton air conditioner operating on 1 00 percent outside air can consume 7200 KWH per month more than a 5-ton unit using 1 0 percent outside air. At 6 cts per KWH this amounts to $432 per month.

During certain months, it is desirable to bring outside air into the building, The ideal arrangement is to have outside air dampers that are substantially closed when it is hot or cold outside and open when it is between 62 and 72F outside.

The initial cost of such a system may be high, but the potential savings often provide an excellent return on the investment. An air conditioning contractor or a mechanical engineer can advise you on the feasibility of this investment.


Laundry rooms are often provided with vent fans that blow air out of the laundry room. The intent of these fans is to remove humidity and heat from washers and dryers, and, indeed, they accomplish this function. The air they remove, however, is usually replaced by conditioned air at significant expense.

Do not air condition laundry rooms if possible. When clothes dryers are in operation they exhaust air from the room. If the room is air-conditioned, the exhausted air is conditioned air, which is expensive and wasteful. If a vent to the outside is provided in laundry rooms to let air in to replace air used by the dryers, conditioned air is not wasted. The savings amount to 1.4 KWH per hour of operation during the cooling season and 0.3 KWH per hour during the heating season.


Nearly all air-cooled air conditioning units installed prior to 1 979 were quite inefficient. If the compressor on an air conditioner fails and if the air conditioner has an energy efficiency ratio (EER) below 7.0, consider replacing the entire compressor/condenser unit rather than the compressor only. An air conditioning contractor can look up the EER rating of your air conditioner.

Replacing only the compressor will not allow your unit to achieve its full rated EER. You may prefer a new unit because air conditioners are now available with EER's as high as 12.0. New air conditioners are being rated with SEER'S, or seasonal energy efficiency ratios. The SEER reflects slightly different test procedures and is somewhat higher than the EER.

A unit with double the EER costs only half as much to operate. Thus, if a 5-ton unit with EER of 5.0 costs $250 per month to operate, it can be replaced with a 5-ton unit with EER of 10 costing $125 per month to operate. It is an easy matter to evaluate how long it will take for the added investment to pay for itself.

Residents of central or north Florida may want to consider reverse cycle or heat pump systems of high efficiency. The new systems provide year-round comfort at much lower operating cost.


Many condominiums use water-cooled air conditioners. Water-cooled (air-to-water) units require a supply of water to absorb heat which the unit has removed from the surrounding air. The water removes the heat by circulating through a heat exchanger coil inside the unit.

If the water circulating through the individual units is not chemically treated, deposits of lime can build up inside the heat exchanger, reducing the efficiency of the unit and adding up to 50 percent to the operating costs. Individual heat exchangers need to be flushed out periodically.

If a well is used to supply cooling water, the need to clean individual units can be reduced by using a large heat exchanger to cool the water circulating through the individual units. Ground water removes heat from circulating water and then only the main heat exchanger needs to be cleaned.

Another convenient way to clean all units simultaneously is to install a cleaning by-pass loop. A cleaning solution is circulated periodically by maintenance personnel.


Time switches are convenient ways to turn lights on and off, but their clocks need to be reset periodically. Photocells adjust automatically, turning lights on when it is dark and off when it is light.

For certain applications, such as turning lights on at dusk and off at midnight, it is convenient to use a combination photocell/time clock control. The photocell is set to turn the lights on and the time clock turns the lights off.

Every hour that 1000 watts of lighting can be kept off saves one kilowatt-hour of electricity.


One of the major sources of heat lobs from swimming pools is evaporation, and one of the best ways to reduce evaporative heat loss is to cover the pool. Covers can be used whenever the pool is unoccupied. They are good investments for both heated and unheated pools.

After installing the cover, you might want to consider a solar heater. Recent advances in solar pool heaters make this a very attractive option. Compare the cost of the proposed solar system with your known heating costs to see how long it will take the solar system to pay for itself.

If you are using electric heat to heat your pool, you can cut your cost by more than 2/3 by replacing the electric resistance heater with a heat pump.

It is a good practice to avoid heating an outdoor pool when temperatures fall below 60F or rise above 80F.


If hot water is provided to occupants by a central water heater rather than by individual heaters in each unit, solar or heat recovery systems might be feasible.

If piping can be conveniently run from the water tank to a suitable location for solar collectors, approximately 75 KWH of hot water can be collected each month for each 1 0 square feet of collector installed. This amount varies according to location and type of collector. Either the Florida Solar Energy Center or your contractor can provide more detailed information.

Condominium owners are eligible for a 40% tax credit on the individual share of the solar system cost as long as the condominium is the primary residence and not a vacation home. If the individual share is $2000, the owner can take a tax credit of $800. The credit applies to domestic hot water systems. Swimming pool systems are not eligible.

If an air conditioning compressor is easily accessible from the central water heater, waste heat from the air conditioner can be used to heat water by installing a heat recovery unit. A 5-ton air conditioner running 10 hours per day can provide 150 gallons of hot water per day during the air conditioning season. It would take 26 KWH of electricity to heat the same amount of water. At 6 cts per KWH this amounts to $47 per month.


If all the air conditioners in a building turn on simultaneously, a phenomenon called peaking occurs. It is analogous to rush-hour traffic and to long lines in banks, post offices, or grocery stores. In order to meet peak electrical demand, the electric utilities need to use peaking generators which are expensive to operate. As a result, everyone pays a higher rate to make up for the increased generation costs.

Control of peak usage by cycling air conditioners on and off on a rotating basis is called load management. Load management simply prevents all air conditioners and/or water heaters from being either simultaneously on or off. In other words, it evens out their use.

Electric utilities are seeking ways to level their peak generation requirements. If you would like to explore the savings potential of load management in your building, discuss the matter with your local electric utility representative.


By making a chart comparing monthly electric bills, a close watch can be kept on consumption patterns. Since costs tend to rise from one year to the next, it is important to record the KWH figures reported on each bill, and then compare the results for the same month of previous years. Large discrepancies often indicate equipment malfunction. Consumption records are also useful for evaluating the effects of conservation measures. Gas and electric bills for the previous year can usually be obtained from your utility companies if your records are incomplete.

If billing is based on a demand rate, the KW demand figures from electric bills should be charted separately. If large differences in KW demand occur from month to month, it may be worthwhile to consider a demand limiting device.


Check the bulb types used in fixtures that are recessed into the ceiling. Most recessed fixtures do not have built-in silvered reflectors. Ordinary light bulbs should never be used in recessed fixtures that do not have reflectors. They cause heat build-up within the fixture, shortening the life of the fixture and sometimes creating a fire hazard.

If you have recessed fixtures without reflectors, you might wish to consider using the new "elliptical" types of flood lights. Tests have shown that if 100- or 150-watt reflector bulbs are used, they can be replaced with the new type 75ER30, 75-watt elliptical floods. Similarly, 75-watt reflector bulbs can be replaced with type 50ER30, 50-watt elliptical floods. A 75-watt bulb uses 25 percent less energy than a 1 00-watt bulb, and 50 percent less than a 150-watt bulb.


Check attic areas to be sure they are adequately insulated. If the insulation is fiberglass or mineral wool, it should be 14-16 inches thick and should spring back into place if it is compressed and released. Cellulose insulation should be 10-12 inches thick and all insulations should be uniformly distributed.

When you decide to add insulation, you will want to use the most effective products available. Not all insulations are created equal and you should balance the pros and cons of each before choosing.

When insulation is installed, it is especially important to maintain a 3-inch clearance from recessed lighting fixtures. Your insulation contractor can provide you with more information on insulation. Bringing your attic insulation up to the U.S. Dept of Energy recommended R-Values is the single most cost effective, energy saving and overhead reducing upgrade you can make to your properties.


overview - large volume attics - soundproofing - fireproofing - home