Light is essential. It enables our perception of form, colour, and texture. It is critical to human health, influencing circadian rhythms and our energy, mood, and productivity.
Emerging research into circadian stimulus led the Well Building Standard to propose and implement new metrics for assessing the circadian stimulus provided by both daylight and electric light. These new metrics require innovative approaches to simulation and means of interpreting data to assess circadian lighting potential during the design process.
Though designers are beginning to look to electric lighting to provide improved circadian function i.e. ‘changing white’ technology, the first step in designing to support circadian system function should be to ensure access to daylight.
Daylight is the most effective way to provide the health benefits of circadian lighting – new methods for measuring and simulating daylight in buildings are critical to ensuring that facade and building designs respond to the most appropriate drivers. Data tells us that rather than illuminating a working plane to a level and uniformity, it is the light on the vertical plane that’s important i.e. the light that enters our eyes when we are sat (or stood) at our workstations.
The provision of lighting that delivers circadian system benefits is growing to be an important health factor in the built environment. Research on this topic is contributing to an ever-increasing body of evidence that our circadian response to sky glow, light trespass, glare and over- or under-illumination affect our health and well-being.
Implementing this can be tricky and difficult to verify in terms of effectiveness during design process. For daylighting in a project, well-known rules of thumb are useful as initial design guidance for simple buildings. However, buildings with complex floorplates, ambiguous or changeable floorplan layouts and complex facade strategies require more detailed analysis to verify that the design fulfils the intent to provide quality circadian lighting primarily through daylight.
The illumination guidelines of WELL Building Standard for light are aimed to minimize disruption to the body’s circadian system, enhance productivity, support good sleep quality and provide appropriate visual acuity where needed.
One of the most important factors to evaluate when designing to meet the Equivalent Melanopic Lux (EML) target is the availability of daylight. Not all light sources are equal in terms of circadian stimulus (CS). Daylight is the best option for both energy efficiency and CS because it requires no energy input and the wavelength spectrum of daylight closely aligns with circadian stimulus.
analysis and modelling of daylighting is key to analyse the maximum daylight
offering before implementing an artificial lighting strategy.