Seeing the light

Are we still in the dark when it comes to daylight design?

There is nothing quite like the warm glow of a sunrise, the way the afternoon sun plays across a room, or how a single ray of sunlight has the power to transform a space. Yes, the effects of daylight are well known in the architecture community, but are they really understood?

Multiple studies have shown exposure to natural light aids health and wellbeing, increases productivity, improves mood, and even helps to save energy and retain staff. However, these studies have also highlighted a need for a greater focus on daylight design, introducing it earlier in the planning process and more comprehensive government lighting standards.

Natural light is an essential design element

According to Andrew Bissell, Lighting Director at Cundall, daylight design should be involved from the very outset of any project.  

“It’s about how light enters a space – thinking about all the rooms, not just basing it on digital models and numbers but also lighting patterns and ensuring light is distributed evenly in every space.”

Every detail from where a building site is located, its orientation and the daylight exposure it receives, to window placement, the balance of thermal heating and the use of glazing can influence building comfort.

“In my experience, many architects tend to, understandably, base their knowledge of daylight on past projects,” says Laura Phillips, Lighting Designer and Associate Director at Arup, “There is a tendency to shy away from specifying daylight systems, as they can be costly to a project if not considered and integrated early on, and the benefits can be difficult to sell to a client.”

Daylight is a commodity

Daylight, when harnessed correctly, has been shown to have massive energy benefits, offsetting the need for less healthy artificial lighting while cutting energy costs by 30% to 45%.

Decades of research has also shown exposure to daylight throughout the working day can improve mental function – including memory and speed of work – between 10 and 25%, and improve productivity by up to 15%.  

Greater access to daylight, and something as simple as having a desk with a view, can also help with staff retention as employees are shown to be happier and take less sick days.

The artificial versus natural light debate 

A lot of new lighting technology has been designed to replicate natural light, but it offers no real benefit. As much as LED and other artificial lighting claims to mimic natural light, it has a very limited spectrum and lacks the naturally occurring colours vital for proper visual performance, and the regulation of hormones and neurotransmitters in the brain – such as cortisol, which is related to stress, and melatonin, a prerequisite to sleep.

That being said, adequate levels of daylight throughout the day are not always possible due to the ever-changing position of the sun, window orientation and amongst other factors. This is where a greater understanding of daylight design comes in.

Layouts need to be designed to balance artificial and natural light, taking into consideration façade reflection, the sun’s movement, glare, shading, light intensity and automation – to ensure spaces are evenly lit, and external and internal elements work together.

Most importantly, lighting needs to suit the function and needs of the occupants of the space. Offices, laboratories, leisure centres and especially schools all have different, specific requirements.

A new standard for daylight

There is growing demand for more detailed daylight standards and clearer parameters to be introduced to ensure daylight design is implemented at the planning stage. Whilst recent years have seen a positive step change with the move from daylight factors to climate-based daylight modelling. There is now a need for further changes, such as introducing the spectrum of the light to the matrix as well as more measurement positions relating to the eye position and viewing direction of occupants.

Andrew Bissell believes, “We need to move away from current light measuring tools as they just look at the amount of light and not how it affects occupants. Measures like melanopic lux and circadian stimulus – which seeks to measure both the visual and biological influences of light – and greater clarity on what ‘health lighting’ means need to be made regulatory standards.”

Daylight design is still considered a “non-discipline” and the responsibility of it sits across the design team. Focusing more on the importance of daylight in the built environment is key, it could be taught to a much greater extent at university level. When lighting specialists are appointed to design daylight schemes for galleries and museums, some staggering results are achieved in the process of ensuring works of art are not damaged by lighting. Yet the same level of service is not afforded many regular buildings we use, is our health and wellbeing less important than preserving art? 

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