The idea of lighting a building from above is not a new one – the Pantheon in Rome has an oculus, or opening, in its domed roof, which was used to light the space inside during the day. However, this method proved impractical across Europe, as the opening would allow the elements into the building.
The invention of clear glass, credited to Angelo Barovier around 1480, increased daylight transmission into buildings, as previous glass had a green or yellow hue caused by iron oxide. However, glass could not be used for areas bigger than 3 feet due to the inability to make larger panes of glass. This meant that its use was limited to smaller windows and roof lanterns in cathedrals.
During the industrial revolution, it became possible to manufacture larger sheets of glass, which were also machine polished – resulting in a much clearer finish. Skylights became a more common feature in homes.
In the twentieth century, a new development in the glass industry occurred: it became possible to mass produce glass fibres. Today, glass fibres can be used as loose rovings, flattened into a sheet as chopped strand matt, or woven into a cloth. GRP (Glass Reinforced Polyester) combines these glass fibres with a thermoset polyester resin – resulting in a strong, lightweight material which can be used in an array of products, from boats to roofing materials.
During the 45 years of manufacturing GRP rooflights, Hambleside Danelaw has advanced its manufacturing technology that is used in the Zenon branded products today for both in-plane and barrel vault rooflight applications.
Rooflights manufactured from GRP by Hambleside Danelaw are installed on the roofs of industrial and commercial buildings such as factories, warehouses, and distribution centres where large areas of rooflights are also required, and these buildings are getting bigger! They provide an easy way to let the freely available resource of natural light into the building. Industrial building type rooflights can also be manufactured from polycarbonate, however GRP comes with several additional benefits when compared to this option.
Through natural diffusion, GRP rooflights distribute daylight evenly throughout the interior space. Although polycarbonate rooflights tend to have higher light transmission, they can produce glare and clearly defined areas of brightness contrasting with shadow and gloom. Glare can have an adverse impact on the
building users’ comfort and ability to function. GRP rooflights significantly reduce glare, and within BREEAM Hea 01 Visual Comfort, will gain project points as part of a glare control strategy. It is also worth considering that solar gain and light transmission are directly linked, meaning that a higher light transmission can result in the building overheating, and therefore, excessive solar gain may create a need for cooling strategies such as uncontrolled ventilation. However, solar gain can have a positive benefit by reducing the demand for space heating!
When specified correctly, GRP rooflights will deliver a lower embodied carbon content than their polycarbonate equivalent. Further lowering of embodied carbon can be achieved by using Zenon Insulator insulation layer, made from cellulose acetate, a recycled wood pulp product which is compostable after its service life. In comparison to polycarbonate insulation layers, Zenon Insulator provides a wider distribution of light and when partnered with Zenon Evolution GRP rooflight material can reduce or even remove the need for artificial lighting during normal daylight hours.
Other advantages of GRP over and above polycarbonate are a lower thermal expansion coefficient that’s more closely aligned with that of surrounding roofing sheets, ensuring a simplified fixing methodology; compatibility with all other materials as standard, including plastisols associated with coated steel; and finally, GRP rooflights can provide a service life in excess of 30 years and satisfy their non-fragility status for 25 years or more.
To learn more about Zenon GRP rooflights, get in touch with Hambleside Danelaw’s sales team on 01327 701920 or fill in the contact form.