Lighting technology has come a long way since the invention of the incandescent light bulb, 100 years ago. We could write a thesis on lighting values, colors, temperatures, etc., which is why there are designers and engineers who specialize in lighting. The lighting in a building effects humans physiologically and psychologically so there is much to be considered with lighting design and selection to create a comfortable environment. About 30 percent of energy consumed in all buildings is for lighting, with about 12 percent energy use for lighting in residential buildings. So what lighting strategies do we want to consider in a ‘green’ home?
Daylighting is a simple approach to using the sun’s light to light our home through the use of windows, traditional skylights, and a new type of skylight called a tubular skylight. A tubular skylight collects sunlight at the roof and through the use of reflectors sends a beam of light to the inside of the house. One 14” tubular skylight can provide the light output of several 100-watt incandescent light bulbs. Tubular skylights also loose less energy than a traditional skylight that delivers the same amount of light.
Window size and placement are not just a consideration for ventilation and how the house looks on the outside, but also how they provide light to the inside. How a room is used should be an integral part of the lighting design strategy for the house. A room used in the morning should be oriented to the east to take advantage of the rising sun, and rooms used in the afternoon, such as a family room, oriented toward west to take advantage of the sun’s light as it travels toward setting. We also need to consider the seasonal course of the sun and provide proper shading to control light and regulate heat gain through some windows.
The position and color of the ceiling and walls will also have an effect on the light in a room. A clerestory, a row of windows near the top of the roof, is another way to get light and solar energy into areas of the house that may have limited windows.
Electric lighting is made up of three components— the fixture, the lamp, (bulb), and the control (switch). Light fixtures are installed as either surface mounted or recessed in the ceiling or walls, or mounted as indirect lighting, under cabinets or in coffered ceilings.
The incandescent bulb, after 100 years of use, is rapidly becoming a dinosaur. Only 10 percent of the electricity used to power an incandescent bulb provides light. The other 90 percent goes to produce heat.
Fluorescent tubes and compact fluorescent bulbs (CFLs) are becoming the standard source of light in a home. The new fluorescents do not have the flicker problems that they used to and are available in a wide range of color to create the appropriate ambiance and meet the lighting needs of the task at hand. The cost to operate a CFL is 25 percent the cost of operating an incandescent bulb. CFLs are also now available as a dimmable bulb.
Light Emitting Diodes (LEDs) are a very efficient light source that have been used in industrial applications, such as automotive and electrical equipment and commercial applications such as exit signs, street lights, and traffic lights. As this technology develops, the LED will become an efficient and affordable choice for residential lighting as well.
Energy efficient lighting controls include dimmers, motion sensors and occupancy sensors. When using dimmers we have to make sure to match the appropriate dimmer to the fixture it controls. Motion and occupancy sensors are energy savers and also provide convenience and safety as well.
Other topics to be addressed in this series will include energy, heating and cooling, building materials, indoor air and environment and solar power.