Paul Smith of the Rooflight Association gives insights from a white paper showing how rooflights optimise daylight in large commercial buildings, to boost wellbeing, energy efficiency, and asset value, and offers some design strategies.
The Rooflight Association commissioned a white paper to provide some evidence for what many already know – daylighting matters. And rooflights are the most effective way to bring natural light into buildings, especially large-span industrial and commercial buildings; making rooflights essential.
The timing of this study is crucial, because without research and strong data, daylighting and rooflights are in danger of being sidelined, as decision makers favour photovoltaic systems to save energy and reduce carbon. As this white paper proves, combining their collective benefits ensures the most favourable outcome for the building’s performance and the people working within it. As the voice of the UK’s rooflight industry, it is our duty to spread the word and ensure that architects, building designers and decision makers are aware of this.
Why it’s important
The white paper provides architects with a deeper understanding of the benefits of natural light and the effectiveness of rooflights in buildings. This knowledge will help optimise daylighting design solutions, considering factors such as health and wellbeing and energy usage, which will lead to better buildings, increased client satisfaction and happier and healthier building occupants.
What’s inside?
The association appointed esteemed Emeritus Professor John Mardaljevic of Loughborough University to research and write the paper, with the support of our technical committee. This approach has produced an authoritative yet accessible paper that’s easy to understand and digest.
The executive summary highlights the key takeaways, while the paper explores the health and wellbeing benefits of daylighting and the commercial and environmental advantages, for example electric light consumption, asset value, and use of space. Energy savings are demonstrated in a comprehensive case study using a 3D model, while design guidance will be of particular interest to architects.
Enhanced understanding of the benefits
The white paper delves into the numerous advantages of natural light beyond just illumination; it gives five of the key benefits of daylighting and rooflights in commercial and industrial building design:
Occupants will be connected to the outside and the natural dynamic changes of daylight inside the building. This is essential to promote a healthy 24-hour circadian rhythm (internal body clock).
Daylighting has been shown to enhance alertness and the concentration of occupants.
Spaces with good daylight are associated with improved staff retention and reduced absenteeism.
Exposure to sufficient levels of daylight is believed to support the long-term health and wellbeing of occupants.
Good daylighting in buildings has been shown to increase asset value and space utilisation.
The most important commercial and environmental benefit is demonstrated in the case study, Daylight Potential and Energy Saving, which uses a 3D model based on a typical roof lit building.
The data reveal that a typical roof lit building has considerable potential to reduce electric lighting energy consumption by using daylight effectively. The study recommends electric lighting be dimmed, or even switched off entirely, in response to available daylight to realise significant savings.
Effective daylighting
Insights from the white paper can be used to inform building design. The study explains why the potential for the effective exploitation of daylight in buildings with rooflights is much greater than in buildings with vertical glazing. It considers the spread of light, how much sky ‘we can see,’ and occupant visual comfort.
Sections three and four look at daylight characterisation, availability and prediction, including the daylight factor and climate based daylight modelling, and lighting level recommendations. The latter compares artificial lighting illuminance levels with the likely occurrence of various daylight levels via a rooflight system and explains why “it is vital to ensure at the design stage that the rooflights will deliver the desired provision of natural illumination.”
To aid modern building design, the ‘new’ daylight standards – the European CEN Standard for Daylight in Buildings (EN 17037) and the WELL Building Standard are also explained in the document.
Essential element in building design
For large-span buildings, daylighting performance is directly related to the proportion of roof area assigned to rooflights. The white paper advises: “For non-residential industrial/commercial building types, this typically 10-20% of the roof area.”
The right layout is also critical to maximise the daylight potential within the building. The most effective layout balances internal requirements, like boosting natural light levels in deep-plan spaces, with practical considerations, externally, such as other utilities and photovoltaic panels on the roof.
Sometimes, these decisions are left to the roofing contractor or metal roofing supplier, but this is often too late. Early engagement is key to an effective rooflight installation. Instead, work with rooflight manufacturers or suppliers in the early planning stages to facilitate the design. They will likely ask for the project goals and then offer a solution to make the most efficient building possible. For ease, many of our members have products listed on NBS Source, or similar, and also offer CPDs.
To conclude, daylighting performance is largely determined by the decisions made at the early design stage and so, we believe architects must consider daylighting to be an essential element in building design if
we are to create healthier, better, more efficient buildings.
Paul Smith is chair of The Rooflight Association