Lighting Power Density (LPD) is a lighting power requirement defined in North America by the

American National Standards Institute The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...

(ANSI),

American Society of Heating, Refrigerating and Air-Conditioning Engineers The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE ) is an American professional association seeking to advance heating, ventilation, air conditioning and refrigeration (HVAC&R) systems design and constructio ...

(ASHRAE), and the

Illuminating Engineering Society of North America The Illuminating Engineering Society (IES), formerly the Illuminating Engineering Society of North America (IESNA), is an industry-backed, not-for-profit, learned society that was founded in New York City on January 10, 1906. The IES's stated mi ...

(IESNA) Lighting subcommittee. Lighting Power Density technically represents the load of any lighting equipment in any defined area, or the

watt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wa ...

s per

square foot The square foot (plural square feet; abbreviated sq. ft, sf, or ft2; also denoted by '2) is an imperial unit and U.S. customary unit (non- SI, non-metric) of area, used mainly in the United States and partially in Canada, the United Kingdom, Bang ...

of the lighting equipment. However, in the lighting industry it is often associated with the lighting power allowance (LPA) permitted by the building energy code in question. The Oregon Department of Energy defines lighting power density as "The maximum allowable lighting density permitted by the code. It is expressed in watts per square foot for a given occupancy/space type."

Primary Calculation Methods

Space By Space Method A defined list of many possible space types within a building the associated watts per square foot allowance. For example, ANSI/ASHRAE/IESNA Standard 90.1-2007 allows the Emergency Space of a hospital to be designed for 2.7 watts per square foot, but the Recovery areas of a hospital would be allowed 0.8 watts per square foot. Whole Building Area Method A defined list of many possible whole building types and the associated watts per square foot allowance. For example, ANSI/ASHRAE/IESNA Standard 90.1-2007 allows manufacturing facilities 1.3 watts per square foot, while parking garages are only allowed 0.3 watts per square foot. Exceptions and Additional Allowances Specific exceptions and additional allowances are defined and categorized further in ANSI/ASHRAE/IESNA Standard 90.1-2007

References

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