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). According to the Chartered Institute of Building (CIOB), 70% of the buildings currently standing will still be here in 2050.
The challenge therefore lies as much in retrofitting existing building stock. Whether “old” (15-20 years+) rooflights are simply replaced with new like for like (bearing in mind that some modern GRP rooflights can guarantee a service life of 30 years), increasing the rooflight: roof ratio or upgrading the insulation performance, it is a comparatively quick and simple fix, that ticks the boxes in improving the building’s emissions.
From personal experience, often rooflights are so discoloured with dirt and age, that the building occupants do not even realise they have rooflights! As a rule of thumb, a GRP in-plane rooflight allows up the three times more light into a building than equivalent-sized vertical “glazing”. Single sheet modern GRP rooflights can provide light transmission of at least 80%; double skin insulating options still yield at least 50%, with the added bonus of enhanced thermal performance. The type of daylight provided is also an influencing factor in the specification process: GRP gives a diffused light, providing greater internal light distribution without solar glare
Historically the accepted lore was that 10% of the roof should comprise rooflights. Independent research commissioned by the The Rooflight Association (RA) now challenges that. The research used SBEM (Simplified Building Energy Model) to quantify CO2 emissions for the notional building with varying rooflight area. The conclusion was that, at 12% rooflight area, it passed the target within Building Regulations Approved Document Part L. A rooflight area of 15-20% achieved savings in running costs of £5.92/m2/yr (at prices current when the report was compiled), and reduced emissions by 28.7kgCO2e/m2/yr. Note, the cost of energy in £ and CO2 required to light a building artificially is accepted to be far greater than any potential heat loss through rooflights.
Upgrading old rooflights to double skin insulating versions delivers the optimum results in terms of addressing the building’s carbon emissions. In the RA research, if rooflights were omitted entirely, total CO2 emissions for the building were 42% higher, and emissions from the lighting systems alone 220% higher than they were with 12% rooflights. If the rooflights are already double skin, replacing the outer weather sheet alone will improve the amount of light entering the building.
A fact many building owners and tenants will not realise is that 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.
The latest innovation is that certain GRP rooflights- i.e. the Zenon brand – can also quantifiably contribute towards BREEAM ratings. Note that whilst we predominantly think of BREEAM as a new build concept, versions can apply to In-Use and Refurbishment/Fit Out schemes. With the current emphasis and awareness of carbon emissions, BREEAM is set to play an increasingly important part in building design, build and refurbishment, particularly as already BREEAM ratings are proven to raise purchase and rental prices of industrial and commercial buildings.
Zenon is the only GRP rooflight in the UK that is independently certified by the British Research Establishment to achieve an Environmental Product Declaration (EPD) which delivers 1.5points when included as part of a metal roof (under the Material Mat 02 category). This is partly due to its pioneering manufacturing process, which produces a GRP material that is stronger than conventional GRP rooflight sheet, yet lighter in weight. It also has 40% less embodied carbon as a result.
This is in addition to any BREEAM benefits achieved via the use of any GRP rooflight in the Energy and Health & Wellbeing categories.
So make the most of a ‘hole’ in the roof, and help save the planet. To find out more about our Zenon low carbon GRP rooflights click here.