Achieving sustainable building
design using rooflights

Rooflights fitted onto flat roofs can save tremendous amounts of energy on artificial lighting and provide excellent thermal performance to retain heat in the winter months and reflect the sun’s UV rays in the summer due to their sustainable building design. Rooflights also ensure an even distribution of daylight into interiors below, creating an invaluable feeling of space in even the cosiest of living spaces.

Rooflights and reducing carbon footprints

It’s been independently proven conclusively that rooflights are an effective choice for sustainable building design. De Montfort University’s Institute of Energy & Sustainable Development probed the effect that rooflights have on the total energy required to operate a building, as well as the yearly carbon dioxide emissions resulting from it. The research found that by installing an appropriate level of rooflights (between 15-20% of the total roof area) will lower energy consumption and the associated carbon dioxide emissions.

The key conclusions of the study were that, in buildings used 24 hours a day, there were CO2 emissions savings of up to 15% in all cases where the rooflight area increased all because of the sustainable building design.

For those designing living and working spaces, it’s important to note that artificial lighting is carbon inefficient, relying on power generated from the burning of fossil fuels. Although artificial lighting will be a necessity in certain parts of the day in the workplace or home – certainly during winter months – it should be controlled by automatic operation on an at-need basis i.e. when daylight levels fall to a specified level. In the winter months, rooflights continue to be effective however, by delivering passive solar gain that can reduce energy costs.

Rooflights and types of daylight

Not only can rooflights encourage abundant levels of natural daylight into a building they are also capable of influencing the type and amount of natural light that can filter into interiors below. This relates to direct light and diffused light, which both have their benefits, and should be considered by architects and designers when determining rooflight areas and the use of spaces below.

• Direct light Rooflights can filter natural light directly through the glass surface, without any interference of disruption. This is filtered as a straight beam, giving impressive levels of daylight to interiors directly below the rooflight but less so in the surrounding areas.

• Diffused light This relates to the scattering or diffusion of natural light into interiors below, resulting in a more even distribution of light. This is better suited for spaces requiring effective ambient lighting rather than strong light for close detailed work or in environments that need to appear very natural.

Rooflights and thermal sustainability

Part L of Building Regulations state that all architectural rooflights must have U-values of 2.2W/m2K or better. Meanwhile the limiting fabric parameters set limits on the worst acceptable standards for insulation values for the building fabric of new dwellings at 2.00W/m2K for rooflights.

This covers the following:

• The area weighted average for all elements of that type. E.g. if one opening and two fixed rooflights were installed to a property, the opening rooflight may be permitted to have a U-value greater than 2.00W/m2K, so long as the fixed rooflights have a much better U-value, resulting in an overall average U-value that’s within the 2.00W/m2K limit.

Building Regulations also define ways to limit the affects of heat gain. Although it states limiting glazed areas such as rooflights as being one solution, it’s not necessary to take such drastic steps given the availability of solar control glazing. This allows daylight to pass through a rooflight whilst radiating and reflecting much of the sun’s heat and rays outside; thus maintaining pleasant temperatures and environments below and mitigating the need for expensive air conditioning.

Rooflight standards and testing

At the time of writing, there remains no harmonised European or British-specific standard for rooflights on flat roofs. As such, the only way to prove suitability, performance and compliance is to gain certification from an independent testing organisation.

The British Standards Institution (BSI) agreed to test Sunsquare’s rooflights under their most rigorous Kitemark standards in a bid to achieve high-quality certification above and beyond CE marking and demonstrate safety, quality and sustainability.

Achieving the BSI Kitemark and ISO 9001 demonstrates a mark of performance, surpassing the benchmark for extreme wind loading, weather tightness and air permeability. The process created a framework for efficiency that enables processes to be improved and tweaked continually.

Sustainable rooflight manufacturing

At Sunsquare, we take the environmental impact of our rooflight manufacturing processes extremely seriously. In fact, we’ve achieved certification for ISO 9001 and ISO 14001, demonstrating our environmental credentials and commitment to reduced waste and energy use.

We’ve also employed a dedicated systems and quality manager, who is continually working to ensure we can add further value to our rooflights whilst removing waste from all our processes.

The company has a strong reputation for rooflight innovation. You’ll find our display of state-of-the-art architectural rooflights at the BRE Innovation Park in Watford, underlining our com

If you’re at the planning stage of a project and you’d like to discuss the prospect of incorporating rooflights into your building designs, please don’t hesitate to contact us to discuss your requirements in greater detail.