Reducing Lighting Power Density of Artificial Lighting
Lighting power density (LPD) is a simple evaluation that signifies whether a space can achieve energy savings. LPD is defined as watts of lighting per square meter of room floor area (W/m2). The analysis focuses on the financial benefits and enhanced energy performance of using daylight instead of artificial light. If, in some cases, there are no options to optimize the luminous flux by any of the previously discussed techniques but enhanced energy performance is still the target, then the most dynamic approach is to reduce the LPD.
All energy-efficient buildings in India provide LPD as per Energy Conservation Building Code (ECBC) guidelines (Bureau of Energy Efficiency, ECBC user guide 2007). They do not exceed the limiting values proposed by the ECBC. In the present building, all spaces follow the same standard. The energy consumption of all regularly occupied spaces turns out to be 215,625.55 kWh/year. A set of reduced LPD values for each space type is also proposed in accordance with the ANSI/ASHRAE/IESNA standard 90.1-2007 requirement, which reduces the energy consumption of regularly occupied spaces to 110,748.16 kWh/year. The existing and proposed LPD values are enumerated in Table 11.5.
The most important effect of LPD reduction is the reduction of the environmental and economic impact associated with excessive energy use.