Kit Cuttle

Author and academic Kit Cuttle is currently visiting lecturer in advanced lighting design at the Queensland University of Technology, Brisbane, and the City University, Hong Kong

What led you to formulate your new theory? Was it a sudden realisation or a slow dawning?
After teaching illumination engineering for many years, where the objective is to provide for task visibility, I moved on to teaching lighting design in 1990. I soon came to realise that the engineering and design approaches have virtually nothing in common. Instead of thinking of lighting as the means for revealing detail, the design approach involves thinking of lighting as influencing the appearance of everything that we see. The perceived brightness or dimness of lighting is a basic aspect of that perception. That led to mean room surface exitance (MRSE), or light reflected from room surfaces available at the eye.

What has been the response so far?
Hugely varied. Newcomers to lighting readily accept it as simple common sense, and seem surprised to find that others see it as controversial. Old hands tend either to regard it as an interesting appendage to established procedures, or they tell me that it is what they have been doing for years.

Do you feel as if you’re saying that the emperor has no clothes?
Yes.

How essential is it that your theory finds general acceptance?
If it finds general acceptance, then the ways in which we specify, measure and calculate for general lighting practice all have to change. Notions of how lighting is to be distributed for efficient application will be quite different, and new principles of luminaire design for general practice will need to evolve. I do not see scope for a compromise: it has to be all or nothing.

Do you regard this as the most important moment of your lighting career?
That’s a hard one. The task visibility approach is, I firmly believe, unsustainable, but also it is deep-rooted. Whether I will see its demise is anyone’s guess.

What’s the next step?
Research. The really important point to grasp is that we switch the basis for specifying the amount of light we provide for general lighting practice from task visibility to perceived adequacy of illumination PAI. We need a research- based photometric unit that serves as a simple and reliable indicator of PAI. I have proposed MRSE on the basis of reason. For application, we need a metric based on research.

Have your say

You must sign in to make a comment.