Imma Boada of Kingspan Light + Air looks at how the need for effective daylight within our schools extends far beyond issues of academic attainment
In 1999, Heschong Mahone Group conducted a comprehensive study that analysed the academic performance of over 21,000 primary school aged pupils. The research was designed to assess whether there was any connection between daylighting levels in classrooms and academic achievement. Its results were startling, showing that students who worked in spaces with high levels of daylight progressed 20 per cent faster in maths tests and 26 per cent on reading tests than those working with the least amount of daylight. It’s now well acknowledged that the need for effective daylighting within our schools extends far beyond issues of academic attainment. Children and staff frequently spend over 40 hours a week inside these buildings, so it is vital that they’re designed to properly safeguard health and wellbeing. This includes ensuring classrooms have adequate levels of natural light whilst carefully addressing potential pitfalls such as ‘hotspots’ and glare.
The benefits of daylight
Both the Education Funding Agency (EFA) and the Chartered Institution of Building Services Engineers (CIBSE) Lighting Guide 5: Lighting for Education stipulates that, where possible, natural daylight should be the primary source of light in educational facilities. From a practical point of view, making the most of this ‘free’ light can save up to 80 per cent in artificial light demand, helping to minimise long-term running costs and maintain best practice in terms of sustainable design. It can also contribute towards the award of credits in BREEAM and features within the WELL Building Standard. A wide body of research has shown that exposure to natural daylight can demonstrably improve pupils’ attitudes, learning rates and attendance. There are several reasons why this is the case. Daylight through windows and skylights is more diffused than light from artificial ceiling lights, providing a more eve illuminance of objects and people. Artificial lights, particularly those containing fluorescent tubes, can also have a noticeable flicker that is distracting and can result in headaches and eyestrain. Furthermore, as natural daylight contains all the colour wavelengths visible to the human eye, it is the ideal lighting source for colour rendition. This means that pupils in a daylit space will be able to identify colours and shades more clearly and in sharper contrast, helping them to better understand and engage with various educational resources. Humans are programmed to be more active and alert during daylight hours, and naturally tire as it becomes darker. Therefore, access to high levels of natural light will reinforce children’s natural circadian rhythms, making them feel more awake and ready to learn during the day and consequently sleep better at night. This is particularly beneficial in sports halls, as they are often used for both physical education and exam situations – which both require high levels of concentration and energy. There are many other health benefits associated with exposure to natural light, which could help to improve mood and reduce absenteeism due to sickness, from killing off certain viruses and encouraging the production of Vitamin D, to easing the symptoms of Seasonal Affective Disorder (SAD).
Design considerations
For these reasons, daylighting should be carefully considered throughout the design process. This will not only ensure that the type of windows and skylights work with the wider architectural vision for a project, but also that they will provide the adequate balanced daylighting required. Natural light is extremely variable and requires careful management. While artificial lighting can help to meet the demand in times of low light, excessive levels of sunlight can cause disruptive glare. This often results in the teacher having to pull down the blinds and turn on the lights. Similarly, too much direct sunlight can cause uncomfortable ‘hotspots’ and pupils may need to be moved around the classroom, or the teacher may have to open windows, potentially causing further thermal or acoustic disruption. With these issues in mind, it is important for lighting designers to take into consideration the minimum and maximum amounts of light the internal spaces will receive. Climate-Based Daylight Modelling (CBDM) is a compulsory EFA requirement for designs submitted to its Priority Schools Building Programme (PSBP). This methodology accurately models the daylight levels of a proposed construction in its exact geographical location at various times of the day throughout the period of a year. Currently, the guidance requires learning spaces to achieve ‘useful daylight illuminance’ (UDI) of between 300 lux and 3000 lux – with 300 lux being the target for 80 per cent of the area. Within this range, additional supplementary electric lighting is not likely to be needed. The EFA also suggests that setting a peak acceptable illuminance “reinforces the need to provide suitable glare control, which modulates the light transmission rather than just eliminating the light”.
Top down
Windows are the most obvious point of entry for natural light to enter a space. However, used alone, they are unlikely to provide a uniform distribution of light, particularly in deep classrooms and sports halls, or in central areas with limited external walls. Additionally, if the school is in a built-up area, direct light from the sky may be obstructed. Therefore, a daylighting scheme that uses a combination of windows and skylights should be implemented to obtain the quantity and quality of light needed. Rooflights have been used within educational building design for decades partly due to the popularity of flat-roofed constructions in these buildings. Recent advancements in rooflight technology has focused on refining their often-contoured shape to enable it to capture more light at low sun angles, such as in the early morning or late evening, regardless of orientation. In addition to having aesthetic merit, modern carefully-honed designs ensure that learning spaces are adequately illuminated for more hours of the day than standard rooflights, thus increasing the students’ exposure to daylight and saving more in artificial light demand. The polycarbonate glazing itself has also undergone many developments to guarantee excellent levels of light transmission for the lifetime of the product. As a material, polycarbonate does not filter out blue spectrum light – the colour temperature associated with morning when we are most alert. Other traditional or industrial rooflight materials can yellow over time, blocking out the beneficial blue light waves and distorting the visual environment. Some of the latest rooflights also incorporate layers containing microscopic prism structures scatter the beams of sunlight, eliminating glare and resulting in a soft natural light ideal for creating a lively atmosphere for learning. Climate control glazing options, including ultra-violet (UV) and infrared (IR) blocking particles, can provide additional protection against solar heat gain, helping to keep the spaces well-lit and thermally comfortable. To maximise the energy and cost savings that can be achieved in each application, precision-engineered rooflights can be used in conjunction with low-energy intelligent lighting solutions. With a combination of smart dimming controls, motion detection and daylight harvesting, these systems can reduce lighting costs by up to 90 per cent by only providing the exact quantity of electric light required in periods of no or low ambient light. Designs are also available with a motorised opening and closing mechanism to offer daily aeration and ventilation, in addition to exploiting daylight. Safety is a vital factor for any roof-mounted product, particularly in schools. It is important to ensure that any rooflights specified meet the correct non-fragility standards and recommended safety measures be considered, such as installing a steel security mesh within the rooflight dome. Tested to the same non-fragility standards as the glazing itself, this mesh can prevent objects or persons from falling through the opening in the roof if the rooflight is removed for maintenance or repair. It can also be a visual deterrent to intruders looking to gain access via the roof. Typically powder-coated white, it does not affect light transmission levels.
A light touch
The lessons of effective daylighting are not just restricted to educational buildings. An increasing number of owners, across a wide spectrum of sectors, are now recognising the benefits that healthy buildings can bring to the wellbeing and productivity of occupants. By applying the latest technologies, specifiers can ensure new and existing buildings are effectively lit with natural light for longer periods during the day, saving energy and improving the comfort of occupants. Kingspan Light + Air offers a ‘Daylighting in the Learning Environment’ RIBA Approved CPD to further assist architects and specifiers looking at daylighting for education facilities.
Imma Boada is specification manager at Kingspan Light + Air