How Buildings Work : The Natural Order of Architecture: The Natural Order of Architecture by Edward Allen Architect & Lecturer Yale School Of Architecture

Author:Edward Allen Architect & Lecturer Yale School Of Architecture
Language: eng
Format: mobi
ISBN: 9780198036661
Publisher: Oxford University Press
Published: 2005-07-13T04:00:00+00:00

But efficiency is not the only criterion in choosing a light source. Incandescent lamps cast a warm-colored light somewhat similar to firelight or candlelight. A person's skin looks warm and rosy tinder incandescent illumination; food looks appetizing; and a room takes on a pleasant glow, especially if its walls are made of warm-colored materials such as natural wood or reddish brick. The reflection of the glowing filament sparkles invitingly in glassware, china, silver, or the finish of an automobile. By contrast, people and food look a bit sickly tinder the bluish light of cool-white fluorescent illumination, and the low-brightness fluorescent source does not create such intense sparkles. Incandescent fixtures also are simple and inexpensive to install and maintain. Thus incandescent lighting still predominates in homes, restaurants, churches, and many retail establishments where warm color and sparkle enhance the appearance of the merchandise. But fluorescent lighting is clearly superior economically in large commercial, industrial, and institutional applications. With the introduction of fluorescent lamps in a wider range of color spectra and shapes, the choice between the two systems is no longer so clear.

In the same range of efficiency as the best fluorescent tubes are high-intensity-discharge (HID) lamps, including metal halide, high-pressure sodium, low-pressure sodium, and mercury vapor lamps. Despite their high output of light, however, many of these sources give poor color renditions, limiting their use primarily to outdoor lighting. But some high-pressure sodium and metal halide lamps with acceptable color characteristics have been developed specifically as high-efficiency replacements for incandescent lamps in interior applications. Unlike incandescent sources, fluorescent and HID lamps require ballasts, which are electromagnetic or electronic components in each fixture that regulate voltage, current, and waveform of the electricity to start and operate the lamps.

Tungsten halogen incandescent lamps are smaller and operate at higher temperatures than standard incandescents. They also are more efficient (though not as much so as fluorescents and HIDs). They provide good color rendition and sparkle, which makes them particularly attractive for homes, restaurants, and retail stores.

Where to place artificial light sources in a building is a question of great importance. Sometimes a poorly placed fixture displays a person or an object "in a bad light," as when a light coming from directly above or below casts underworldly shadows across even the most pleasant of faces. Sometimes a badly located lamp can place an object in shadow, as is the case when a right-handed person tries to write in light coming from a lamp at the right-hand side of the desk. Sometimes a source of light intrudes into the field of vision and causes distracting or damaging glare. Shielding or diffusing devices within the light source can do a great deal to counter this glare, but usually it is preferable to locate the source outside the normal fields of vision of persons using a given area.

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