Dr Kevin Kelly, President-Elect SLL, and Head Electrical Services Engineering, School
of Electrical Engineering Systems, DIT
In EN 12464 minimum requirements for lighting are laid down for both interior (Part 1) and exterior (Part 2) lighting. In particular, minimum values for average maintained illuminance, minimum colour rendering and maximum glare are specified. Historically, equal illuminance across the whole working plane was the goal of lighting designers. However, this is wasteful of energy because the working plane was interpreted as the whole plan area of the room.
For offices, 300/500 lux was specified, depending on whether work was mainly PC-based or paper-based. This resulted in high levels of lighting throughout the space, whether needed or not, and often for periods extending beyond the working day. These days such energy inefficiency is unacceptable.
New recommendations, such as those specified in the SLL Code for Lighting 2012, provide a pragmatic balance between adequate lighting to perform the task efficiently and quickly, and financial costs. The SLL Code for Lighting is based on quantitative recommendations that meet minimum lighting requirements, but also acknowledges there is now a need to target lighting more carefully.
Modelling of people in offices to ensure good visual interaction is now recognised as being important, and good-quality lighting and energy efficiency are now as important as quantitative specifications. Good-quality and efficient lighting in buildings also includes the need to maximise daylight penetration.
Maximising daylight offers opportunities to lift the spirit with natural light and so daylight must be carefully designed into the building, along with the artificial lighting and controls, to create good-quality and efficient lighting in a space. There is a growing consensus in industry that the way to address this challenge is to use a holistic design approach – integrating the design of the architecture, glazing and engineering design. Input is needed by the architect, structural engineer, surveyor, heating and ventilation engineer, electrical engineer, lighting designer, interior designer, control systems engineer and most importantly the client and facilities manager.
Modern Building Information Modelling (BIM) software facilitates such a holistic approach with multidisciplinary interaction and the use of BIM is expected to grow exponentially in construction projects in the years ahead. The EU is encouraging the use of LENI, the Lighting Energy Numeric Indicator. SLL is of the view that the targets set by EN 15193 with respect to LENI are modest and is presently addressing this issue with the UK authorities in order to set more stringent targets for the UK building regulations (2013).
Effectively, a good quality LENI will aid lighting designers to move away from installed load benchmarks to more meaningful consumption targets, and hence take account of the benefit of good quality controls. This is particularly beneficial in buildings where daylight penetration is high or where there is intermittent occupation of the building.
While standards, demands and design methodologies change, there is also major change happening in lamp technology. The development of solid state lamp technology is revolutionising lighting; with any revolution there is collateral damage and early adaptors of poor quality LED (Light Emitting Diode) lamps are among the casualties. A study by Philips Lighting (2012) estimates that while only 6% of lighting was solid state in 2010, 75% of lighting is expected to be LED lighting by 2020.
Similarly, McKinsey estimates LED lighting will be a €65 billion industry by 2020 but is more modest about the overall use at 60%. At present the biggest applications of LED lighting is for stage, external lighting, architectural lighting, retail, cold rooms, transport and hospitality. LED lamp technology is expected to impact upon office and general lighting in more interiors in the future.
To sum up, this is an exciting and challenging time for the lighting industry with huge growth potential for LED lighting and improved lighting controls generally. We are challenged to provide robust solutions that maximise the benefits of new technologies, while protecting our clients from poor-quality products and installations.
We must maximise light quality and minimise energy use by integrating daylight with appropriate artificial light in a way that lifts the spirit of those using the space and enables them to operate and override automatic lighting controls when required. We also have to ensure the reliability of products we specify and this is particularly challenging when
Dr Kevin Kelly is President Elect of the Society of Light and Lighting (SLL). He chairs the organising committee for the CIBSE/SLL International Lighting Conference scheduled for Croke Park on 12 April next. He will also make a lighting presentation in a seminar at the Energy Show in the RDS on 11 April next.