Lighting Design Framework – holistic approach
An integrated design approach is necessary for lighting design. This can be done with six elements that influence lighting design. They all need to be considered for best possible solution.
The Lumen Method of Lighting Design
This method is used to determine the number of luminaires for a given lighting level.
E= F/ A
F = EA (Lux X Area) (Lumens will help determine the total amount of light required in the room)
Many more factors affect the amount of light reaching the work place
Steps for the calculation
Design flexibility is an advance approach which allows a space and lighting design to be used for different functional requirements at different time. The key benefit for the same is the effective use of materials and space. Advance lighting design should be flexible to:
One of the important measures to cut down the energy use in artificial lighting is to effectively use the day light available. Researches have shown that spectrum wavelength of natural light generates nearly 2.5 times of lumen per watt of additional cooling load through solar gains compared to artificial lighting. With additional measure life energy efficient lighting and low –e glazing, the lumen performance could be increased to 3 times per watt of solar gains compared to artificial lighting.
The day light integration should be well planned to ensure that the natural light is not responsible in increasing the cooling load of the space. As a rule of thumb, the average day light lux level under peak sunny condition should be less than five times the required lux level of the space as per NBC. For eg., if the NBC prescribed lux level of a space is 100 lux, the day light levels at a peak sunny day should not exceed 500 lux at any given time. This will keep the cooling load under check and save the electricity consumed by artificial lighting.
The day lighting could be linked to a day light sensor which either switch the lamps on or off or dim the lamp based on day light availability. The design mark the area with a day light potential based on the visual light transmittance of glazing, glazing type, and internal reflection and integrate the sensors on the lamps installed in the day light zone. These lamps will use day light for all the hours with sufficient day light available. One of the disadvantages of this approach in day light integration is the problem of glare. Glare causes the uncomfortable brightness in an area forcing occupant to pull down the window drapes and use artificial lighting only for visual purpose. In order to overcome this problem, application of daylight blind sensors are recommended. The blinds function automatically to reduce the glare and allow indirect day light to entire the space. The application of such devices could reduce the requirement of artificial lights in day light zone by 70 – 80% in a sunny day.
Energy Conservation Building Code and Lighting Design
Lighting is one of the most complex section of building design. The lighting designer has to juggle a number of considerations related to lamp technology and luminaires, lighting design philosophy, energy efficiency, and aesthetics.. International standards, therefore, have specified lighting efficiency requirement in terms of lighting power density (LPD) in order to provide flexibility to the designer to meet the design as well as the efficiency requirements. LPD sets the maximum lighting power per unit of area of a building category or space function classification.
Bureau of Energy Efficiency, a statutory body under Ministry of Power, has launched Energy Conservation Building Code in May 2007 to set the minimum energy efficiency requirement of a building. One of the key sections of the code is on lighting. ECBC has set the minimum LPD requirement for whole building or for each space function to quantify the maximum allowed lighting power for a respective category to meet the lux level requirement prescribed in NBC. Designer has to meet the LPD and lux requirement based on any possible design solution, philosophy, lighting technology, and fixture. The LPD requirement of ECBC 2007 is listed in table below. These LPD values was developed in 2007. In last one decade market has transformed significantly and many advance technologies are now available with better efficacy. BEE is in process to update the ECBC code to reflect the current market standards. In order to design a NZEB, it is recommended to achieve LPD values 30 – 50% efficient then the requirement stated in ECBC 2007.
|Space Function||ECBC 2007 LPD (W/m2)|
|First three floors||6.5|
|each additional floor||2.2|
|For religious buildings||18.3|
|For Performing Arts Theater||28.0|
|For Motion Picture Theater||12.9|
|For Bar Lounge/Leisure Dining||15.1|
|For Family Dining||22.6|
|For food preparation||12.9|
|Dressing/Fitting Room for Performing Arts Theater||6.5|
|For Performing Arts Theater||35.5|
|For Motion Picture Theater||11.8|
|Banking Activity Area||16.1|
|Hotel Guest Rooms||11.8|
|Highway Lodging Dining||12.9|
|Highway Lodging Guest Rooms||11.8|
|Card File and Cataloging||11.8|
|Corridor/Transition | control room||5.4|
|High Bay (>8m)||18.3|
|Mall Concourse 1.1||18.3|
|Sales Area (for accent lighting, see sec 9.6.3(c))||18.3|
|Court Sports Arena—Class 4/ indoor||15.1|
|Court Sports Arena—Class 3/ indoor||15.1|
|Court Sports Arena—Class 2/ outdoor||24.8|
|Court Sports Arena—Class 1/ outdoor||24.8|
|Ring Sports Arena||29.1|
|Terminal—Ticket Counter 1.||16.1|
|Fine Material Storage||15.1|
|Medium/Bulky Material Storage||9.7|
|In active storage||3.2|