Lighting manufacturers are waking up to the fact that daylight, or a close approach to it, is key to human health.
For example, research by Anjali Joseph at the Center for Health Design in the US found that: 'Higher light levels are linked with better performance of complex visual tasks. Light requirements also increase with age. By controlling the body's circadian system, light has an impact on outcomes in healthcare settings by reducing depression among patients, improving sleep; lessening agitation among dementia patients; easing pain; and improving adjustment to night-shift work among staff.
'The presence of windows and access to daylight have been linked with increased satisfaction at work. Exposure to light is critical for vitamin D metabolism in the body and is also used as a treatment for neonatal hyperbilirubinemia.'
While lighting could and should be a vital consideration in the design of healthcare buildings, the importance spreads way beyond there.
Partly this is because of society's concern with well-being; that it is important to keep people healthy, rather than just wait until they are ill and then treat them in hospital.
Good lighting also has immediate and more tangible benefits in productivity terms.
Philips' ActiViva range of lamps, for example, has a very high 'colour temperature' and emits a lot of blue light compared with traditional uorescent lamps, coming near to simulating a blue sky. We know anecdotally that this makes us feel good, but a controlled study in a distribution centre in Belgium went further. When ActiViva lamps were installed, not only did the staff like them, but they also reported fewer headaches, and performance rose by 10 per cent. The only drawback is that these lamps cannot be mixed successfully with conventional 'warmer' lamps, since the visual contrast is striking and aesthetically displeasing.
Zumtobel is a lighting manufacturer that, surprisingly, advocates the use of less, not more, artificial office lighting.
It believes that dedicated 'daylight-harvesting blinds' must be specified if daylight is to be brought into buildings without glare and heat gain.
These will filter glare, reect sunlight back outwards and redirect daylight inwards. Slats can be tilted at different angles, minimising solar gain while maximising daylight.
Zumtobel Lighting recommends that such blinds be used in conjunction with fully automated controls driven by readings of a sky scanner on the building's roof, linked to the artificial lighting. This directly contradicts the philosophy that people should have control over lighting in the work environment, but Zumtobel argues that this is the only way that technical blinds, daylight and artificial light can be fully integrated.
In many buildings, manual blinds are rarely adjusted. Where technical blinds have been installed, empirical evidence shows that if people are given control, typically within only one to two weeks they are satisfied to allow the blinds to work automatically.