The Mathematization of Daylighting: a history of British architects’ use of the daylight factor
Measuring the extent of sky, visible at a window, using a dot diagram overlaid on a fisheye photograph, a methodology developed by Peter Tregenza and Michael Wilson.
Copyright: Alan Lewis
British post-war planning guidance proposed that cities be rebuilt according to scientific principles. Mathematical tools were devised to determine built form; daylight levels within buildings were to be evaluated using a metric called the daylight factor.
Developed in the 1930s, the daylight factor is a measure of the illuminance within a room (usually on a horizontal plane), relative to the total amount of light that would be available under an unobstructed hemisphere with an overcast sky, expressed as a percentage. Although the precise calculation used has developed in intervening years, the daylight factor is still the principal metric used in guidance on daylighting.
Recent research indicates that many new-build housing schemes do not comply with recommended daylight factors, and that few architects undertake daylight factor calculations when designing buildings, a cause for concern given the proven health benefits of daylight. Some commentators argue that the daylight factor is now obsolete.
This study will explore whether the Modernist ambition, for buildings to be designed according to mathematically verifiable principles, was realised in relation to daylighting. Specifically, the study will explore whether the daylight factor was successful in promoting good daylighting and, if so, what prompted the apparent decline in its use.
This study is co-sponsored by Thomas Pocklington Trust.
Alan Lewis is a Research Associate in the Manchester Architecture Research Centre at the University of Manchester.
His research focuses on the intersection of Government policy and architectural practice, with a particular interest in the production of design guidance and the study of its effects on the built environment.
He has previously studied the ways in which mathematically verifiable principles, such as Newtonian mechanics and traffic statistics, were used to generate street layouts in post-war urban planning.