Electrical contractors, rather than architects, engineers, or lighting consultants, are often asked to design/build lighting in commercial, institutional, residential, and industrial structures. Besides choosing components for cost and practicality, the contractor must also select energy-efficient lighting tools. This is because the Federal government has been involved in conserving natural fuel resources since 1989 with the first American Society of Heating, Refrigeration, Air Conditioning Engineers/Illuminating Engineering Society of North America (ASHRAE/IESNA) Standard 90.1. In 1992, it began to eliminate energy-inefficient lamps.
The standard covers the building envelope; heating, ventilation, and air conditioning (HVAC); power; and lighting. These criteria will soon enter enforceable building codes in every state. This means that everyone involved in a building––whether it is new, existing, altered, or added to–– will have to be aware of the requirements.
As much as 35 percent of available energy in a structure may be used for lighting. Obviously, light is essential for any human activity. Good lighting increases attendance, productivity, sales, and personal comfort, while conserving electricity.
However, if artificial light is used unwisely, it can waste energy, require expensive maintenance, be uncomfortable, and create increased air conditioning loads from the heat normally emitted by light. But, how many in the industry are already familiar with the ASHRAE/IESNA Standard 90.1? (Standard 90.2 covers low-rise residential structures.) How many follow it?
A better understanding of where light is really required and how to deliver it can do much to reduce energy use, while actually improving illumination and protecting irreplaceable objects. For millennia, ever since fire was discovered, there has been an ongoing search for illumination that provides safe, energy-efficient, long-lasting lighting with minimal maintenance. Several architectural lighting tools now satisfy these criteria. They are much more energy efficient than the conventional incandescent, tungsten, and fluorescent models featured in the Standard’s tables.
They include light pipe and glass fiber-optic lighting systems (not to be confused with the communication version). Light pipe and fiber optics follow the same physical law of total internal reflection, where the light rays are conveyed along an opaque container from a source to where needed. In the former, long, rigid three- to eight-inch conduits are used for ambient (general) light in large or exterior applications or to delineate large exterior spaces (like a skyscraper). In contrast, fiber optics consists of thin, flexible light guides that can be fished through walls, ceilings, or floors, to provide either directional or ambient illumination. Installation is as simple as fishing copper wire.
End-emitting fiber optics, where the light emerges from the tail end of an octopus-like factory-assembled ‘harness,’ is functional. Conversely, the side-emitting type, which glows like neon but needs less maintenance, is solely for decoration.
Fiber optics comes in two different materials: glass and plastic. The properties of glass make it most practical for permanent functional architectural illumination, such as task, display, architectural contours, and even ambient illumination, the latest innovation. Plastic is best suited for temporary, decorative purposes.
Highlights of the Standard’s Lighting Segment
The Standard’s revised lighting section seeks energy conservation primarily through lighting control and total building wattage limitations. Both interior and exterior applications are included.
ASHRAE/IESNA has produced a more simplified minimum standard to save energy. However, depending solely on minimum criteria will not produce the best results. Obviously, better lighting can be achieved with more inventive components. For full details, refer to the Standard itself, which is available through ASHRAE or IESNA.
NOTE: In order to make Standard 90.1 easier to understand and comply with, lighting systems should be included in the tables that are more energy-saving than the conventional ones now given. Items marked with "**" are those where these additional tools should be considered. The combination of efficient components with controls will be more effective.
* Interior lighting control requirements are designed to assure that lighting is turned off when facilities are unoccupied (except where safety or security is involved), primarily through programmable building lighting controls or occupancy sensors.
* Exterior lighting controls requirements are designed to assure the lights are off during daylight hours—primarily through photosensors.
* In addition, there are individual manual control requirements for **accent, task, and demonstration lighting.
* **Hotel rooms are required to have one master control switch at the main room entry that is capable of turning off all lighting in the room.
The standard specifies limits on the amount of total wattage used for lighting throughout a building by establishing a total lighting power allowance. This is determined in two ways:
* Building Area Method: Building square footage times total lighting watts per square foot specified for that building type. Total wattage can be used at the lighting designer’s discretion.
* Space-by-space Method: Wattage for each individual space is totaled to build total lighting wattage budget. This budget can be used as the lighting designer chooses.
* **Additional lighting power is allowed for decorative lighting, fixtures designed to minimize glare on VDT screens, and retail accent lighting. If this lighting equipment is not installed, no additional power is allowed—"use it or lose it."
* **The standard specifies limits on the amount of total wattage used for exterior building entrance and exit lighting by establishing a total exterior lighting power budget. This is determined by totaling the lighting power allowed for all exits, entrances, and canopied areas of entrances. This budget can be used at the lighting designer’s discretion.
* **Additionally, lighting power is allowed for façade lighting. This power budget is based on the total area of the exterior building surface being illuminated. It is not part of the total exterior lighting budget and is only allowed if façade lighting is installed.
"Good Design is Good Business." The American Institute of Architects, and Business Week and Architectural Record magazines, are encouraging property owners and their construction teams to employ higher-than-minimum standards to create more profitable and comfortable buildings. Under revised codes requiring increased energy conservation, the potential market for retrofitting to comply with these restrictions is huge. Those practitioners offering innovative ideas for distinctive energy-efficient lighting will be in great demand.
KAY is president of Conservation Lighting International, Philadelphia. She can be reached at (215) 568-0923.