I have always been passionate about universal design and accessibility for all ages. Lighting for seniors has been an area of interest for me. This post is inspired by my recent experience vacationing at a 5-start resort with my parents who are in their golden years. I opted for the subject “Lighting for the 40+” instead of the more prevailing “Lighting for Seniors” due to the fact that most people experience some performance declines with age in vision by the age of 50, with the effects beginning to become noticeable at 40 years of age. Good lighting guidance for aging eyes in ANSI/IES RP-28-07 promotes wellness and reduces accidents. It deserves greater attention from a much broader audience.
- Uniform ambient / general illumination with flexible task lighting – Older eyes take longer to adjust to changes in light levels. The adaptation time is much greater when transitioning from light to dark. Together with the increasing glare sensitivity with age, excessive contrasts and harsh shadows increase visual fatigue and impair the ability to model faces, recognize and navigate changes in elevation and obstructions. Surface brightness of ceiling-to-wall or immediate-surround-to-task “luminance ratio” should be within 3:1. In addition, transitional spaces help to balance light levels in adjacent spaces and reflected light from matte finishes wash out harsh shadows.¹
- High illumination with glare control – As we age, the pupil becomes smaller; therefore significantly less amount of light reaches the retina (see RP-28-07 Figure 1). Refer to RP-28-07 Table 2 Minimum Maintained Average Illuminance for ambient and task lighting for adults aged 60 years and older (p. 19); Table 3 recommended horizontal and vertical illuminance for Senior Living Environments (p. 25).¹ Refer to the “>65” columns in the IES Lighting Handbook, 10th Edition for illuminance recommendations, which double the “25-65” recommendations.² Aging also slowly clouds the human lens which leads to increased light scattering and glare. Since aging eyes are more sensitive to glare, avoiding enhanced light directed to the eyes and bright light sources in the field of view is essential to maintain maximum visual performance.¹
- High color rendering (CRI > 85) and full spectral power distribution (SPD) light sources for better color and white rendering – With age, the eye’s lens darkens, filtering out short blue-violet visible light making white appears yellow and colors less vivid. This makes it more difficult to distinguish between blue and green.¹ Contrast sensitivity of both brightness and color decreases as we age. “It is estimated that a normal 65-year-old requires about 2.5 times as much task contrast as does a 20-year-old to see equally well” (RP-28-07, p. 7). High CRI with deep red rendering R9 would offer the deep reds, cyan and violet needed to render faces, food, fabric, furniture and finishes more naturally and vividly. Full SPD with short-wavelength blue violet light makes white whiter, thus increasing overall color contrast and clarity.
Now, getting back to my family vacation, we spent a few days at an elegant and sophisticated mountainside resort in Taiwan during the holidays. Perfect location, zen architecture and decor. Everything seemed serene and perfect until the sun started to set… the dark areas became darker and the bright areas became bright hot spots. Being a lighting designer, I naturally thought there would be some indirect ambient or general illumination to lessen the harsh contrast and shadow patterns produced by the small halogen spot downlights. Well… it was pitch-black outside of the floor-to-ceiling windows and the general lighting I expected never came on. I realized that the public areas in the resort were illuminated only by small aperture halogen spot downlights! Starting to get concerned, I stayed close to my parents’ side to make sure they didn’t slip and fall or run into glass doors. Mom actually missed the glass door entrance to the dinner lounge on the 2nd night. She told me it didn’t look like there was an entrance door at all! Dad got irritated couple times saying this resort was great during the day but too dark to make him feel secure at night. I myself experienced uneasiness sitting under a spot light at the dinner table while the surrounding area was in the shadow.
Below are a few photos I took at the resort to illustrate some of the lighting issues –
- ANSI/IES RP-28-07 Lighting and the visual environment for senior living, 2007, reprinted 2011
- The IES Lighting Handbook, 10th Edition, 2011