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ESTABLISH DESIGN CRITERIA |
LIGHTING DESIGN CODES
The main organizations that stipulate the lighting-related building codes are:
(a) American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE)
ASHRAE has formulated the ASHRAE/ IESNA 90.1-2010 which lays down the building codes for lighting under Section 9. More information on ASHRAE can be viewed at http://www.ashrae.org.
(b) International Code Council (IECC)
The International Energy Conservation Code (IECC) has been prepared by the International Code Council. More information on the IECC can be found at www.energycodes.gov/
(c) National Fire Protection Agency (NFPA)
NFPA 101, Life Safety Code should be referred to, especially for egress lighting, during the lighting design process. More information can be found at http://www.nfpa.org/aboutthecodes/aboutthecodes.asp?docnum=101
Below is a 2011 summary of lighting design codes that must be kept in mind when designing an interior space:
Egress Lighting
- Egress lighting is lighting provided to aid in exiting a building or a space in the case of an emergency.
- Lighting requirements typically range from .1 to 1 fc (1.1 to 11 lx) minimum, maintained on the path of egress, as well as exit signs of appropriate size, luminance, and color located at paths and egress ways indicating the direction of exit and actual exit point [1].
- The codes generally require emergency lighting to be provided at all exits and any aisles, corridors, passageways, ramps, and lobbies leading to an exit. Both general exit lighting and exit and area of refuge signs must be lit at all times a building is in use [2]. The intensity of emergency lighting should not be less than 1 fc at any point and not less than 0.1 fc measured at the floor level on the path of egress [3].
- Exit signs must be illuminated by not less than 5 fc at the illuminated surface. A contrast level of not less than 0.5 must be provided as well [4].
- Exit lighting must be connected to an emergency power source that will assure illumination for at least 1 ½ hours in case of power failure [5].
Type of Luminaire
- Only fire-tested and labeled luminaires should be used in interior spaces. The Nationally Recognized Testing Laboratories (NRTL) Program recognizes organizations that meet the safety requirements by OSHA to provide the assurance that the products are safe for use in the US. Underwriters Laboratories (UL) is one of the more widely recognized organizations for lighting. A designer should specify luminaires from an organization approved as an NRTL for safety and liability reasons [6]. For more information, visit their website at http://www.osha.gov/dts/otpca/nrtl/
Luminaire Thermal Protection
- Thermal protection of all luminaires is a necessity for those lights recessed into ceiling and wall construction with cavity voids where insulation may be present or close proximity to construction materials will occur.
- In commercial construction, “thermal breaks” around the luminaires are designed to keep the insulation at least 3” from any component of the luminaire.
- In residential construction, IC-rated luminaires are typically required [7].
- In addition, if the lighting fixture is used in an enclosed space, ventilation to prevent excess heat buildup may be required.
- The NEC also places restrictions on the luminaires installed over bathtubs and shower areas. No part of a hanging luminaire, pendant fixture, track fixture or ceiling fan can be within 8’ above the top of the bathtub rim or within 8’ above a shower threshold [8].
American Disabilty Act or ADA-compliance
The American Disability Act requires the following:
- Wall sconces should not protrude more than 4” beyond the face of the wall and the bottom of the wall sconce should be least 6’-8” AFF. If they protrude more than 4”, they should be mounted at least 80” from the finish floor level [9].
- An illuminance level of 5fc (50lx) is required at elevator thresholds [10].
- The height of switches should be between 15” and 48” for wheel chair users [11].
- The outlets should not be above 15” above the finish floor level [12].
Sustainable Lighting Design
- The most popular sustainable building metrics and rating system used in the United States is Leadership in Energy and Environmental Design (LEED). LEED certification "provides independent, third-party verification that a building, home or community was designed and built using strategies aimed at achieving high performance in key areas of human and environmental health" [13]. To qualify for lighting-related LEED credits, the following sections should be referred to in the LEED Reference Guide [14]:
(a) Light Pollution Reduction under Sustainable Sites (SS),
(b) Controllability of Systems - Lighting under Indoor Environmental Quality (IEQ)
(c) Optimize Energy Performance and Minimize Energy Performance under Energy and Atmosphere (EA)
(d) Reduced Mercury in Light Bulbs under Materials and Resources (MR)
For more details, please visit http://www.usgbc.org/DisplayPage.aspx?CMSPageID=1988
- Lighting usually accounts for 20% to 50% of electricity consumption in a building depending upon the building type. The ENERGY STAR program by the U.S. Environmental Protection Agency and the U.S. Department of Energy labels, identifies, and promotes energy-efficient products to reduce greenhouse emissions [15]. For information on lighting-related ENERGY STAR products(lamps and lighting controls), please visit http://www.energystar.gov/index.cfm?c=sb_guidebook.sb_guidebook_lighting
Lighting Power Density
- The lighting power density establishes a maximum allowable installed lighting power level. The limits are expressed in watts per square foot (W/ft2). These may be given as whole building limits, with a single W/ft2 that applies to all the spaces in a building. They may also be given by space category, with higher values for spaces with more demanding visual tasks [16].
Check in the following website: http://www.lightingcontrols.com. Under the State Energy Codes option, scroll down for a specific state. For example, North Carolina can be found at http://www.lightingcontrols.com/support/statecodes/excerpts/excerpts.asp?state=NC
- The table on the web page above for North Carolina, for example, shows the interior power density allowances for different building or area type in North Carolina. Energy codes that specify limits in installed lighting power also include rules for calculating the installed lighting watts. These rules require identification of the types and quantities of lamps, ballasts and luminaires, and the wattage of lamp/ ballast combinations. Default lamp/ ballast wattages may be used when the equipment’s make and model are unknown. These rules encourage designers to select more efficient lamp/ ballast/ luminaire combinations, because they yield lower installed wattages, but they also require designers to document the equipment’s better performance [17].
- The Building Codes Assistance Project at http://bcap-energy.org provides custom-tailored assistance on building energy code adoption and implementation with code information by location and building type.
References