You sometimes see standard light bulbs being used in recessed downlights. This is inappropriate, since a standard bulb is an inefficient lamp for this kind of fixture, radiating light in almost all directions rather than just one. As a result, the fixture traps a good deal of the light and turns it into heat. In the cooling season, this heat creates additional load on the air conditioning system.
Rather than a standard light bulb, a reflector lamp should be used in a recessed downright. Because of its design, a lower wattage reflector lamp can project the same amount of light as the higher wattage standard bulb. And there are some new, even lower wattage standard reflector lamps on the market, that may be satisfactory for your needs.
If your lamps are recessed in the fixtures, you can probably save an
additional 50 percent on your lighting costs by replacing 150-watt R (reflector) lamps
with 75-watt ER (ellipsoidal reflector) lamps. At half the wattage, these lamps
focus their light down, out of the fixture, and onto the surface to be
illuminated. If the amount of light now being projected is satisfactory, you can save
energy dollars by replacing the standard floodlamp with a lower wattage ERs.
Costing more, but producing even better savings, there are compact fluorescents designed for use in downlight fixtures. The compact can provide the light with only one fourth to one fifth the electricity required by the incandescent, but note that a compact with a reflector will not necessarily project light with the same distribution as a reflector incandescent. If you do not use your do enough to justify the purchase price of the compact, the less expensive incandescent ER may be the better choice. Even with an incandescent ER, energy costs saved can be substantial.
| Cost/kWh | 2 Lamps | 8 Lamps | 24 Lamps | 48 Lamps | ||||
| .05 | $21 | $86 | $257 | $514 | ||||
| .07 | $31 | $123 | $369 | $738 | ||||
| .09 | $40 | $160 | $481 | $963 | ||||
| .11 | $49 | $198 | $594 | $1,188 | ||||
| .13 | $59 | $235 | $706 | $1,412 | ||||
| .15 | $68 | $273 | $818 | $1,637 |
If you need more light, you can try a higher wattage ER lamp or extender that will bring the front surface of the standard flood lamp closer to the opening of the fixture. As with any lamp change, try a few ERs before totally converting, to see if the light output and quality are what you want.
Lower wattage substitutes for conventional PAR spots and floods are available. Among the newer lamps are a 65watt substitute for a 75watt 1amp, and a 120-watt for a 150.
