Usually, you'll determine the appropriate light level needed for a particular space by using the guidelines recommended by the Illuminating Engineers Society (IES). However, it's important to interview the client thoroughly to determine any preferences or requirements they may have that will affect the lighting design.
For example, the owner of a building might mention that he wants low operating and maintenance costs. This would lead to a design incorporating long life lamps, probably using as little incandescent equipment as possible, with high efficiency lamps and easily maintained fixtures.
The space itself greatly determines the type of fixtures installed. For example, an office with a high ceiling may require pendant hung fluorescent fixtures to get the light closer to the work plane. Many offices today have cubicle furniture that can be rearranged. This situation usually requires task lighting in the cubes combined with general lighting in a uniform arrangement. Upscale offices might require incandescent lighting to highlight art work or plants.
To some clients color rendition may be of concern. The type of facility usually helps determine just how important this may be. A warehouse facility usually doesn't require good color rendition whereas most retail facilities do. In general, the more upscale the facility, the more likely that color rendition will be important. If the owner has invested in upscale carpets, wall finishes and art, then you can bet they'll want to show it off.
While energy efficiency may not be stated as a requirement, you may still want to provide a design that incorporates the option of high energy efficiency. A life cycle cost analysis will show the long term benefits of the increased initial costs. If it turns out that new equipment must be purchased anyway, the incremental cost difference will be very small, resulting in a quick payback. In addition, some utilities will work with customers to help them get high efficiency equipment installed. As another selling point, more efficient lighting means less air conditioning will be needed. This could reduce the size, and thus the cost, of air conditioning needed. In retrofit situations where the air conditioning is already at capacity, energy efficient lighting can eliminate the need for additional cooling capacity.
