The solution to reduce the carbon footprint? Rooflights!


Under pressure to reduce the carbon footprint? Look to the roof to help.

In the drive to reduce the construction industry’s carbon footprint, the “easy fix” is clear- the rooflights. Working in the roofing industry, you may think that is stating the obvious. It acknowledged that rooflights ( by which, for the purpose of this article, I mean in-plane industrial rooflights) offer benefits in light transmission and insulation, reducing the need for supplementary internal artificial lighting and heating.

But what about the rooflights themselves?

Careful selection of the composition of an industrial rooflight can reduce the carbon footprint, in more ways than one. Evolution in manufacturing processes means that GRP materials are highly environmentally-friendly in their production process. Innovation in the insulating materials provides greater scope to choose options that have a lower carbon footprint. Don’t forget, carbon footprint applies to the whole life, the “cradle to grave”, of the product, not just its production.

Therefore, the easiest way to reduce the carbon footprint is to choose a British made solution!

Look too at the manufacturing process. Not all GRP rooflight sheeting is the same. Most manufacturers use the traditional method of pultrusion, where a base polyester matt is reinforced with glass fibre. The latest evolution is to lay a continuous woven mat of glass filaments onto the polyester. This yields a material that has 40% less embodied carbon as a result.(

GRP rooflight sheeting also has added benefits for you as the contractor/ installer. It is lighter in weight, so it is easier to handle on site, and needs less structural support. Yet it goes way beyond the minimum requirements for non-fragility, enhancing site safety and reducing wastage. The process also enables finer definition of profile, which means easier attainment of weathertightness: a better, more reliable seal is achieved between the GRP rooflight and abutting metal roof reducing the risk that you may be called back to site for remedials.

The choice of insulation material further influences the rooflight’s carbon footprint. The conventional solution is multiwall polycarbonate. Development in green technology has seen the introduction of a low carbon alternative- cellulose acetate. As an added benefit, cellulose acetate can be composted at end of life. The fundamental difference is that as you increase the thickness of polycarbonate to improve insulation, the inevitable trade-off is light transmission due to the reflectance of light off each horizontal layer.

Cellulose acetate has a honeycomb structure, that traps and contains the air in small pockets within the rooflight cavity.The core comprises a lightweight, transparent cell structure that is perpendicular to the plane of the rooflight. This requires only a single thin clear film layer to encapsulate the air pockets and has minimal interference with the light transmission. Thus, for the same U value  a 13% increase in light transmission can be achieved


More importantly with regard to carbon footprint, typically, polycarbonate contains up to 18 times the amount of embodied carbon as cellulose acetate (depending on specification/ structure:

Why do I need to worry about carbon emissions?

The government has a commitment to reduce greenhouse gas emissions by the United Kingdom by 50% on 1990 levels by 2025. On a local level, some councils are setting even more stringent targets. The built environment inevitably is being challenged to help contribute as it is responsible for nearly 40% of the UK’s carbon footprint(1). Building owners and occupiers also increasingly realise the benefits in reduced running costs of improving a building’s sustainability. Further, there are various tax relief schemes for businesses that operate more efficiently and produce waste that is less damaging to the environment.

They are appreciating that benefits can be applied in existing buildings: bear in mind, according to the Chartered Institute of Building (CIOB), 70% of the buildings currently standing will still be here in 2050. Thus, they will be looking to you to support your customers by suggesting ways in which they can build or refurbish their premises to be more eco-friendly.

It costs four times more to heat a building as it does to light it. Improving the thermal performance is therefore not just good for the environment, it is good for their bottom lines too. Any small incremental increase in the cost of upgrading to a higher specification i.e. a double skin in place of single skin, is more than offset by the savings in running costs. A double skinned GRP rooflight with an outer weather sheet, internal liner panel, and a transparent insulating core can attain a U value as low as 0.9W/m2K.

Natural daylight too is proven to enhance occupant wellbeing and performance, again having a positive impact on their bottom line. Natural light creates an improved working environment so employees are more productive, it can reduce risk as they can more clearly see hazards. The combination  can lead to fewer days lost through sickness absence.

So make the most of a ‘hole’ in the roof, and help save the planet. Full details of Hambleside Danelaw’s rooflight sustainable solutions can be found at: