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General Seating Lighting

Measurement

Luminance is a measure of the density of luminous intensity in a given direction. It describes the amount of light that passes through or is emitted from a fixture, and falls within a given solid angle. A common unit for luminance is candela per square foot or the short term is foot candles. The list below gives an indication of the recommended amount of light needed for reading or general use.

Task Area (Ft-candles)

  • Corridors/Stairways/Restrooms (10-20)
  • Storage Rooms (10-50)
  • Conference Rooms (20-50)
  • General Offices (50-100)
  • Classrooms (50-75)
  • Cafeterias (50)
  • Gymnasiums (30-50)
  • Un-covered Parking Areas (1-2)
Specification of illumination requirements for each given use area is important. Analysis of lighting quality is needed to insure that adverse components of lighting (for example, glare on the projection screen or incorrect color spectrum for reading or for video ) are important to the design. Artificial light sources are usually evaluated in terms of quantity and the overall luminous efficacy.

Artificial lighting consumes a significant part of all electrical energy consumed worldwide. In churches from 20 to 50 percent of total energy consumed is due to lighting. For some buildings over 90 percent of lighting energy consumed can be an unnecessary expense through over-illumination. The cost of that lighting can be substantial. A single 100 W light bulb used just 6 hours a day can cost over $35 per year to use (.14/kWh). Thus lighting represents a critical component of energy use in churches. There are several strategies available to minimize energy requirements in any building:

The LED has the most promise as a energy efficient light source but has high installation costs. A lower cost alternative is to use a combination of T8 fluorescents with dimmable ballast and tungsten halogen down lights that are dimmable. This combination will provide flexable lighting system to adjust for different services and uses. Although the last three light sources are the most efficient they are not dimmable and provide illumination that is too “industrial looking” for a church worship area.

In summary lighting for the general seating area of a church should consider window design to allow the maximum of natural light. For general seating area the most energy efficient would be a combination of high efficiency fluorscent dimmable fixtures and dimmable compact fluorescent. In addition, LED PAR lights can be used for accent lighting.

On the front worship platform dimmable 250W halogen lighting PAR cans would be used. The lighting levels should have an average of 25 foot candles (using flood PAR38 at 35ft distance) in the seating area and 50 footcandles on the worship platform (using PAR38 Flood at 25ft heigth)

As the cost of LED lamps is reduced and brightness increased, more emphisis should be placed on their use.