Approximately 13.5% of the Australian population are over 65. To be more specific, the amount of this group of people is about 3,250,000. According to the Australia Bureau of Statistics, this percentage will be up to 15.3% and continue to climb in the next 20 years. Therefore, aged people care is one of the most important affairs in our daily agenda.
When people are getting older, there will be some significant changes of their vision that occur which affect their understanding and perception of the world around them. Four changes are evident:
If we apply these physical changes in vision into considerations when designing lighting systems for older eyes, we come up with the following needs:
On the most basic level, the goal of lighting design for older adults is to increase lux level, which is measuring luminous flux per unit area, without increasing glare. An excellent way to accomplish this when ceiling heights are sufficient (generally a minimum of 8'6", preferably 9', for indirect lighting) is through cove or indirect light that is bounced off the ceiling. This indirect lighting provides even, low-glare illumination. However, because the ceiling absorbs some of this light, it requires more foot-candles to achieve adequate lighting. Daylighting and dimmable fluorescent are good indirect ambient light sources. An ambient light level 2 to 3 times “normal” is considered appropriate, with additional carefully designed task and accent lighting to allow older eyes to see what they are doing safely and effectively.
On a bright day, a person entering the building from outdoors might have to stop and wait up to 90 seconds for his or her eyes to adjust to the lower light levels indoors. Excessive differences in lighting levels should be avoided in transition areas between driveways, garages, entries, lobbies and corridors as well as where flooring changes occur. The best way to do this is by having higher light levels that automatically switch on when necessary. Consider using motion sensor switching to turn on coves, sconces, overhead illumination with frosted diffusers and other non-glare lighting (such as linear lighting in lower height placement) in these transition areas. Other technologic advances include voice-command light switches. These are available through many home technology catalogues, but are not widely used as of yet. Also, consider lighting design ideas that add safety to night-time trips to the kitchen and bathroom, such as motion sensors and/or energy efficient, long-life sources that can burn all night without using a lot of energy or causing frequent lamp replacement.
Traditional Incandescent lights add to this problem since they emphasize yellow and red. This effect is even stronger when dimming the fixtures because the filament burns at a lower temperature. It is important that bulbs meet the appropriate Colour Rendering Index (CRI), so that colours appear natural (i.e., as they are seen in sunlight). For residential lighting applications, the main colour-correct alternatives to “yellowing” Incandescent bulbs are Fluorescent, Xenon and Halogen. These bulbs also provide cost-savings because of their long life (compare to incandescent) and energy efficiency.
The two types of glare that affect our eyes are direct glare (from a directly visible lighting source, such as an unshielded bulb) and indirect glare (a consequence of bright light bouncing off reflective surfaces, such as shiny floors). Therefore, bare bulb fixtures should be avoided because they cause glare spots to which the older eye is actually painful. Use frosted diffusers and indirect lighting where possible, such as cove lighting, sconces and toe-kick lighting previously mentioned. Shiny floors provide another source of glare when they reflect ‘hot spots’ of overhead bulbs. Consider using working surfaces, flooring, appliances finishes, etc. that have matte surfaces in order to reduce the effect of reflection in your universal designs.