ExclusivesThinkingHealthy Buildings Heroes: Ruth Kelly Waskett on the power of daylighting

Work in Mind’s Sophie Barton speaks to Ruth Kelly Waskett, Project Director at Hoare Lea and a recent President of The Society of Light & Lighting. She is passionate about the power of daylighting to heal both people and planet... By Sophie Barton
Sophie Barton2 weeks ago18 min

It’s not every day that you hear lighting likened to sweet treats, but expert Ruth Kelly Waskett has an astute analogy. “When it comes to lighting, I often draw parallels with nutrition,” she says. “You can get your calories from chocolate, or you can get them from vegetables, but it’s not quite the same. Those calories are packaged differently and received differently by your body, and with lighting it’s similar.”

Ruth is talking here about the difference between artificial lighting and daylight. While both are essential to our lives, there are fundamental variations between the two. The full light spectrum can only be found in daylight and, even on a cloudy day, it still provides more powerful rays than anything you’ll find indoors. Add to that its mood-boosting, vitamin D enhancing qualities, and it is a formidable life force.

“Daylight and artificial light have very different characteristics, and we know that we need natural light in order to thrive,” says Ruth. “I’m very interested in how we integrate the two – it’s easier said than done. I’m particularly passionate about daylight, because it’s so crucial to architecture and to our lives. We need it in the same way that we need food and water, and as lighting designers one of our major focuses is on harnessing it and using it as part of a holistic lighting design practice.”

Ruth’s lighting credentials are certainly impressive. She is Project Director at engineering consultancy Hoare Lea, and immediate Past President of The Society of Light and Lighting, a division of CIBSE that works with the world of light, lighting and its design or application. A highly skilled daylight specialist, she also lectures on the subject at UCL and has a PhD in smart glazing – plus she has been designing buildings for over 20 years.

Lighting for people

It is a powerful CV, and Ruth is passionate about extolling the many virtues of daylight, especially within the workplace. After all, we know beyond doubt that light and wellbeing are inextricably linked. Light kickstarts our body clock and influences our mood, energy levels, sleep and visual comfort. But while the light-dark cycle has shaped the rhythms of human existence for centuries, many discoveries around light and our wellbeing are relatively recent.

“Around the year 2000, it was discovered that we have light receptors in the back of our eye that exist purely to regulate our body clock,” says Ruth. “We always think of the eyes as being there so we can see, but perhaps their first purpose was to enable us to synchronise with the light / dark cycle of the earth. We know we need a good a good blast of light in the morning period, in order to reset our body clock every day – it’s like resetting a watch that goes slightly out of time. So, when it comes to designing buildings, it’s particularly important for people to have light exposure in the mornings.”

Architectural advantages

Ruth adds that there are psychological and even architectural benefits to incorporating light into a workplace too. “It means prioritising windows, which then give you a connection to the great outdoors,” she says. “Even in an urban environment, you’ll see a few pigeons and be aware of the weather patterns. Just being able to see the sky and get those visual cues about the time of day and the seasons is very important to our wellbeing. Having the opportunity to look into the distance through a window is good for our eyes too. It relaxes the muscles that are involved in working with a screen and, without those opportunities, we can suffer eyestrain.”

Indeed, numerous studies point to the dividends of daylight. Research by Cornell University Professor Alan Hedge found that workers in office environments with optimised natural light reported an 84 percent drop in symptoms of eyestrain, headaches and blurred vision symptoms. Likewise, workers sitting close to a window that optimised daylight exposure reported a 2 percent increase in productivity.

On the flip side, studies suggest a persistent lack of daylight – or repeated exposure to light at the wrong time – has the potential to be harmful. Light keeps the clocks in our cells synchronised, something which is critical for optimal health. Disruption to the body clock can lead to symptoms of SAD (Seasonal Affective Disorder), sleep issues and potentially may even increase the odds of certain cancers.

A lack of legislation

Despite all this, Britain has been slow to introduce legislation to ensure workers have sufficient access to natural light. While countries including Germany and Sweden have legal minimum standards, the UK’s guidance is vague at best.

“There are guidelines and standards around daylight, but none of them are legally binding,” says Ruth. “Lighting is all-too-often seen as just another building service, but it holds the key to providing enjoyable and health-supporting spaces for people.”

Of course, in recent years LED systems have revolutionised the lighting industry. While ‘old fashioned’ tungsten or incandescent bulbs didn’t emit blue light, LED systems can be engineered to more closely replicate natural light.

“This means we can develop light sources designed to deliver the circadian-boosting light when we need it,” explains Ruth. “And when the sun goes down, this artificial lighting can be extremely supportive. It can deliver warmer temperatures, to help our bodies wind down towards bedtime, and has a huge ability to create a visually stimulating or intimate atmosphere through colours and pools of light.”

The ecological impact

But while LED systems are revolutionary, Ruth says they are no magic bullet. She explains, “there is an energy impact to artificial lighting – in order to deliver the blue parts of the spectrum, you need to put more watts in. It literally costs energy and money to make it circadian-effective.

“Of course, we do need to make buildings that are great for people, but we need to think about sustainability too. If there’s no planet, nobody will care how they feel in a space. Ultimately, we have daylight, so can we not make use of that to support our circadian systems, instead of spending energy trying to do that with artificial lighting?”

In contrast, natural light has huge potential for energy savings. And the answer, Ruth believes, is to have daylight at the top of the agenda when designing new buildings.

“If done right, daylighting holds the key to solving the people/planet conundrum,” says Ruth. “With natural light, people get exactly what they need, when they need it, and artificial lighting energy can be minimised. It’s a win-win, but it requires a re-think in the way we plan our cities. Buildings are too often designed to fill large square plots. If buildings were shallower, we will have less density and better daylight ingress. But the viability of many developments depends on the building footprint being maximised in the plot.”

Retrofit limitations

Of course, improving the natural light in existing workplaces is more complex. “We can improve daylighting by using lighter coloured finishes on major surfaces, such as walls, floors and ceilings,” says Ruth. “And we can design the interior layout to ensure people spend most of their time it the best daylit areas. But we are often very constrained by existing openings in the façade, and swapping the core of the building for an atrium is a drastic approach – even atriums have their limitations.”

And when it comes to new projects, there is a delicate balancing act between light and thermal comfort. Swathes of glass may seem the obvious solution, but these can have heat and health implications.

“Overheating kills people, it’s serious,” says Ruth. “Of course, lack of light exposure can have serious health consequences too, but it can take decades for that impact to show. So, heat is much more heavily controlled by building regulations, which is only right. When we work with architects to improve daylighting, we always have to be mindful of not creating an overheating issue.

“That said, certification standards like BREEAM and WELL have helped us enormously, because they give an external driver. If a building is aiming for BREEAM ‘excellent’ for example, one of the targets is around daylighting. We can then work together with the client to address any lighting deficiencies and improve the building, which is so rewarding for everyone involved. It’s always a joy to work with a client that clearly prioritises employee wellbeing.”

A pioneering project

One such project is Timber Square, a vast Landsec development in Southwark. Currently under construction, it aims to be the largest commercial development in the UK to use cross-laminated timber. Not only is it targeting net zero in construction and operation, but the two office buildings will meticulously balance daylight and thermal performance.

“It’s a remarkable project,” says Ruth. “We’ve done extensive daylight analysis, and worked with the architect – Bennetts Associates – to develop the façade design around daylight and overheating. Each façade has a different orientation, so the light profiles vary, as does the potential for overheating. A lot of buildings are designed in a very homogenous way, but we’ve ended up with a façade that has different degrees of openness as you go up and around. It’s an exciting

design that actually responds to the environmental conditions and urban landscape. It’s been such a pleasure to work on – being able to shape a building to maximise daylight is incredibly satisfying.”


Ruth Kelly Waskett is immediate Past President of The Society of Light and Lighting and Project Director at Hoare Lea. She recently spoke at Let’s Talk About Light, an event organised by leading UK manufacturer Tamlite. The thought leadership forum helps consultants and designers to see a deeper connection between people, planet and light.

Ruth Kelly Waskett is immediate Past President of The Society of Light and Lighting and Project Director at Hoare Lea.

Sophie Barton

Sophie Barton is our Features Editor. She a journalist and editor with 17 years’ experience in the national media, specialising in wellbeing and lifestyle.

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