To Measure Is to Know … or Not

Sayings such as “to measure is to know,” “if you cannot measure it, you cannot improve it,” and “what gets measured gets done” can be traced to at least William Thomson, who later became Lord Kelvin.† These insights have been applied to advance all manner of human endeavors. Progress in science, engineering, sports performance, and business relies on measurement, which has evolved into data science and data analytics and may be coupled with machine learning and artificial intelligence.

Data driven decision making offers many benefits. At a personnel level, data motivates employees to focus on items that will be sorted and counted, which vary with job type and may include things such as sales revenue, product defects, research funding, publications, or teaching ratings—all of which are intended to support organizational outcomes. Within a buildings context, data may encourage more efficient operations. Building management systems coupled to data analytics software have the potential to improve maintenance, energy efficiency, and indoor environmental quality.

Smart buildings rely on data, but since garbage-in leads to garbage-out, what we choose to measure matters a great deal. The quantities that we measure and track must have rational, reliable, and robust correlations with intended outcomes. In lighting, we often measure and compute the things that are easiest to measure and compute. Horizontal illuminance receives a disproportionate focus, even knowing, uncomfortably, that illuminance is rarely a suitable proxy for the many benefits that quality lighting has the potential to confer.

In lighting application, a narrow focus on easily measured quantities can stifle creativity and innovation. Lighting relies on science and engineering, but it is also an artistic contribution to the built environment with potential to evoke emotion, guide attention, direct movement, support health, and create delight. This is not to say that we should discard data. But when measures marginalize creativity, the results are inevitably banal. The architectural equivalent of pop music—competent at some level, but reduced to formulaic solutions with mass appeal.

The tension created by different approaches to lighting reflects where we are in the continuum of knowledge acquisition. The fact that existing measurements and quantities do not enable full evaluation of how light affects people, plants, animals, and objects means the lighting research community has lifetimes of work ahead of it. Meanwhile, the design community has job security because their solutions, which balance the technical foundations of light with artistry, cannot be reduced to measurements that are available to us today.

† The full quote is: “I often say that when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science, whatever the matter may be.” (Thomson 1889).