The interest in skylights has significantly grown in the construction world, and skylights are becoming an increasingly integrated part of a building’s execution. Not only have skylights vastly improved from a technological aspect, but they have also been incentivised by building regulations and the BREEAM environmental assessment method.
Additionally, skylights bring benefits that have been recognised by regulatory and assessment bodies, with polycarbonate much improved and now in the ascension of being key skylight material.
The Daylight Factor and BREEAM Ratings
In terms of BREEAM ratings, passive daylight gains credits under Health and Wellbeing Section HW01, as well asEnergy Section E01.
Additionally, reducing carbon emissions can help achieve compliance with Part L of Building Regulation, saving energy from lighting and heating. Skylights also reduce the need for electric light with its corresponding CO2 emissions and cost.
Skylights play an increasingly integrated part in architectural design. Although it is still being built upon, the core regulation for daylighting is the BS 8206-2. More and more, designers are expected to consider more holistic aspects of daylight, including factors like orientation and location.
A well-designed building with a good spread of natural light — typically 15-20% of the roof area in skylights — will ensure sufficient daylight enters the space, reducing the need for artificial lighting. With building systems being considered as full of interdependent factors, lighting controls are also important to maximise the benefits of skylights.
1. Space And Function
Within any building, lighting requirements also depend on the layout of each space and its function. For example: in offices, occupants prefer windows as their source of daylight, perhaps for the reason that it seems like an obvious solution.
Skylights (which bring correspondingly greater benefits than vertical fenestration) contribute to the BREEAM sustainability ratings of new buildings and fulfill the desire of increased daylight. With their versatility of designs and typologies, polycarbonate skylights can be applied in all kinds of building types.
2. Reducing Carbon Emissions
Within buildings, lighting specifications can cut down on energy usage and resulting CO2 emissions by deploying skylights alongside a lighting control system, thus gaining compliance with Part L of Building Regulations.
The Target Emissions Rate (TER) is a key measure of performance and is dependent on the percentage of skylight coverage of the roof. It has been shown that increasing the skylight area from nothing to 10% significantly reduces emissions and continues to do so as skylight area increases to 20%.
To meet Part L 2A of Building Regulations, polycarbonate skylights will be expected to have a U-Value of 2.2 W/m²K. Triple skin units may be needed to maximise this potential, and high performance glazing can reduce the U-Value even further to gain BREEAM credits and a far more energy efficient building.
3. Avoiding Glare, Gaining Airtightness
It is important to coordinate lighting so that glare is avoided. This is achieved by carefully planning the placement of skylights.
BREEAM also encourages best practices in skylighting to ensure solid airtightness, taking into account pre-existing windows and the robustness of installation.
4. Acoustic Performance And Watertightness
Skylights affect external noise ingress performance and bring about a sound reduction of approximately 28-32dB, compared to outside.
Another consideration is the watertightness of roof glazing, which is variable depending on the gradient of installation. BS 5516 recommends a minimum pitch h2of 15° and skylights of different designs, such as domes and barrel vaults.
It is vital to specify non-fragile skylights. CDM 2 regulations require architects to avoid risks and to have measures that control safety factors, including handrails, platforms and grills.
Polycarbonate is considered to be a non-fragile material and shows high levels of durability and light transmission.
Polycarbonate Skylights: The Way To Go
Polycarbonate skylights are an efficient way to achieve the above goals and to gain higher BREEAM ratings. As achieving a rating of ‘Excellent’ can make a difference to lettings, and a BREEAM assessment judged before planning permission is given, it is vital for architects to consider BREEAM guidelines when designing skylight cover.