What is luminance contrast and how do you measure it? The non-technical explanation is the contrast of the light reflected on one surface compared with that of another, adjoining or adjacent surface. For example the contrast between the kitchen bench and the cupboard below and the wall behind.
So why do we need such contrast? Not everyone has perfect vision, colour discrimination, or visual perception. Contrasts provide good visual cues and create greater safety especially in areas like the kitchen and bathroom. Lee Wilson lists the many things in and around the home and public buildings that need such contrast. He explains in more detail everyday items that we might not think of: coat hooks, locker handles, buttons, switches, toilet seats, floors/walls, and more.
As our populations age we will have more people experiencing low vision. This means that contrasts between objects will become an increasingly important factor in negotiating the built environment. Although standards stipulate a certain luminance contrast and levels of light (lux) for buildings, how are they measured, who measures them, and what are they measured with? This issue was investigated by a team in Norway using staircases for the case studies. They found that the tools used by builders and planners vary, and this results in different contrast and light readings for the same staircase. Other variables were also found to influence the readings, such as reflection or glare from overhead lighting. Sunny or cloudy conditions, the shadow of the measurer when measuring, and different angles and positions of the meter all bring different results.
The findings and conclusion of the study raise an important question: Are the staircases as bad as they seem in terms of not meeting the legislative requirements? Or are the requirements too difficult to fulfil? The team concluded that the answer lies with a representative group of people with low vision guiding them on understanding usability. Another case of standards being useful but not entirely effective – the users have the answer once again.
L.D. Houck1 , K. Gundersen, O. Strengen: Universal Design 2016: Learning from the Past, Designing for the Future. H. Petrie et al. (Eds.)
This article is published online with Open Access by IOS Press and distributed under the terms of the Creative Commons Attribution Non-Commercial License 4.0 (CC BY-NC 4.0). doi:10.3233/978-1-61499-684-2-382