With the Government legislating for the UK to become net zero carbon by 2050, every gram that can be saved is going to count.
Hambleside Danelaw’s Zenon brand of GRP rooflights is uniquely able to support construction’s contribution, through a raft of sustainable features & benefits.
They are the only brand of GRP in-plane rooflight to have attained Environmental Product Declaration (EPD) from the Building Research Establishment (BRE), which means they can tangibly contribute towards a building’s BREEAM (Building Research Establishment Energy Assessment Method) rating.
As a result, Zenon GRP in-plane rooflights contribute a minimum 1.5 points towards BREEAM when used as part of a metal roof system in the Materials category. They can further help in the Energy and Health & Wellbeing categories ENE01 and HEA1.
Beyond BREEAM, rooflights reduce the need for supplementary artificial lighting, and heating. A building with 10% rooflights can require supplementary electric lighting for 30% more hours in a working year than a building with 15% rooflights. It is not just electrical consumption impacted by using Zenon rooflights. Typically a rooflight can achieve 1.3W/m2K or better, saving heat energy. Indicative data for various rooflight permutations can be viewed on the Zenon website using the configurator tool, facilitating an understanding of the specification options.
Zenon GRP rooflights do not emit any chemicals once installed, so are safe to use with grey water systems, and in green roof schemes. At the end of their life they can be broken down into constituent parts and turned into Solid Recovered Fuel (SRF).
Zenon Evolution GRP in particular uses pioneering technology to employ less resin in the manufacturing process, resulting in a lighter weight, high strength sheet with good light transmission. The use of Zenon Evolution as the weather facing sheet creates a rooflight that is up to 40% lower in embodied carbon than conventionally reinforced alternatives offering equivalent strength.
Additionally, the use of Hambleside Danelaw’s pioneering and patented cellulose acetate Insulator core will offer improved U values compared to traditional multi-layered systems, and lower embodied carbon in a material that is biodegradable at the end of its life.
So in the battle to find sustainable strategies, look up to the roof, and make the most of the ‘holes’ in it.
Full details of Hambleside Danelaw’s rooflight sustainable solutions can be found here
Modern industrial Rooflight systems form an integral part of the overall roofing system. Once correctly installed they complete the roof and perform the valuable job of bringing natural daylight into the building.
The level of daylight that a rooflight system can give depends on the type of system, the materials used to construct it plus the quantity and position of the rooflights installed.
Looking just at the construction of rooflights it’s important to understand that regardless of whether the rooflight is made from glass, polycarbonate or GRP the performance is affected by the number of layers in the rooflight. The more layers the greater the level of reflectance which in turn causes less light to be transmitted into the building. If this isn’t recognised, then the light level in the building won’t be as expected and increased artificial lighting will be needed to compensate.
Remember the ‘Walkie Talkie’ building? That’s an excellent example of what can happen if reflectance isn’t understood.
To ensure that specifiers and building owners can rely on the technical data being quoted for their rooflights, Hambleside Danelaw asked the National Physical laboratory (NPL) at Teddington to independently measure the light transmission data and ensure that data quoted is totally reliable.
Hambleside Danelaws innovative approach to product development saw the launch of our patented Zenon Insulator core which significantly outperforms traditional rooflight insulation cores in regard to light transmission. The honeycomb like system transmits significantly more light into the building, which will reduce the need for artificial lighting resulting in lower CO2 emissions and operational energy costs.
It’s a well understood fact that our current building stock is a cause of a vast amount of the emissions that are feeding climate change.
The main focus has been on a combination of improved thermal and energy efficiency and yet one important element of the building fabric, rooflights, have largely been overlooked. This is surprising as in many large industrial and logistics buildings they are the main source of natural daylight. Whilst current GRP rooflights can achieve service lives well in excess of 30 years, those installed in older buildings and those that either haven’t been maintained or have adverse environmental conditions, could be under performing in bringing light into the building. The consequence of this is that the building users will have to be more reliant on artificial lighting and as a result will both increase energy bills and CO2 emissions.
The solution is simple…
By replacing the rooflights with a modern GRP rooflights system the internal daylighting will be transformed, energy bills and emissions can be cut as artificial lighting is minimised. This is exactly what happened at a Distribution Centre in Warrington where the building and roof, which was over 25 years old, were comprehensively refurbished.
The picture below shows the dramatic contrast between the refurbished roof to the left and the yet to be refurbished rooflights on the right.
This project also utilised Hambleside Danelaws superior strength and low carbon Zenon EvolutionGRP sheet. A product reinforced with a continuous filament woven glass mesh, significantly
exceeding the minimum requirements for non-fragility as part of the roof assembly.
As we now come to terms with our Governments commitment to achieve carbon neutrality by 2050 its time to look up and grasp the opportunity to use the most renewable energy source; natural daylight.
“They’re just a hole in the roof that lets the light in.”
“We just specify one rooflight in the middle of each bay.”
“I’ve always been taught that 10% rooflights is plenty.”
All of these statements can cost you money and efficiency in your completed industrial or commercial building.
Many Architects and contractors believe that specifying rooflights for the design of an industrial building can often be something of an afterthought.
As long as they install roughly 10% of the roof area as rooflights, they’ve pretty much got it covered, haven’t they?
After all, they all let in daylight and surely that’s all that matters, isn’t it?
No, it isn’t – And here’s why it matters…
Natural daylight is our most abundant and accessible resource. It sustains and supports the vast majority of the earth and is critical to our wellbeing. On the most fundamental of levels, natural daylight is the natural state for human beings. It is the environment in which we have evolved and in which we are at our most comfortable.
It is natural daylight that has a whole range of positive effects on building occupants. Exposure to daylight enhances mood and energy through the release of endorphins. In fact, daylight is critical to mental wellbeing – as evidenced by the growing understanding of the condition known as SAD – Seasonal Affective Disorder, caused by inadequate exposure to daylight.
In factories and warehouses, high daylight levels contribute to increased productivity, improved levels of safety and reduced absenteeism.
But there’s another extremely important factor that’s been the subject of significant research over the last two decades – one which plays an increasingly important role in building design today and will continue to do so in the future – energy saving.
Rooflights, via the provision of daylight, contribute benefits to a building which are additional to those delivered by the roof system. They are a key component and, in some instances, essential to achieving regulatory compliance.
Electrical lighting energy represents nearly 20% of global energy consumption. Therefore reducing energy demand by introducing more daylight into buildings should be a priority for specifiers. This cannot be fully achieved by simply specifying a roof system without giving proper consideration to the rooflights.
The balance between daylighting, electrical lighting, heat loss and solar gain is a delicate one. It involves maximising the reduction in lighting energy usage and minimising heat loss without overheating the building. At Hambleside Danelaw we can provide a wide range of rooflight configurations to enable you to maximise the energy saving potential of your building envelope.
Looking at the wider picture rooflights can also contribute to BREEAM.
These contributions are easy to achieve, low cost and, moreover, they are ADDITIONAL to any BREEAM contribution from the specified roofing system. It would be wise to consider the rooflights from the outset – ideally RIBA Stage 1 or 2 plan of works to maximise their BREEAM impact and “lock” it in to the building specification. However, given the low-cost element they are also useful to utilise even at later stages as replacement contributions where they may have been missed. The contributions all fall within the highest weighted categories:
Materials, specifically MAT01, MAT02 and MAT03
Health and Wellbeing
Contact Hambleside Danelaw to find out how we can help you enhance your project. We can shed light on the important design considerations to deliver maximum efficiency to the building.
Rooflights play a vital role in the modern building but are often overlooked.
They are the common link to many aspects of building design and can help the designer, the building owner and the occupier to achieve a truly more sustainable, energy efficient and enjoyable place to work and to live in. Well considered rooflight design at the outset of the building concept can have dramatic efforts on all aspects of the building from the owner’s potential asset value to the well-being and productivity of the occupants.
Buildings that provide high levels of natural light have more positive working environments than those which are dependent upon artificial light. It is known that people respond better to working in natural light conditions, as the eye and brain functions work better, resulting in improved concentration and overall performance. Plus, of course, less dependency on artificial light significantly reduces energy consumption and running costs as well as impacting positively on the buildings overall carbon footprint.
In new buildings where high levels of insulation are now being installed, the most significant savings in energy can be realised through the utilisation of the free resource that is natural daylight. The energy consumed by artificial lighting, far exceeds the relatively small amounts of heat energy that are lost through increasing the rooflight area which is a small part of the whole building fabric. The amount of energy required to light a well-insulated building is far greater than the amount of energy required to heat it and can be the greatest single energy use in the operating the building.
Of course, artificial lighting will always be essential in occupied buildings subject to occupational requirements, particularly in the winter months or in areas where localised specific or constant lighting levels are required, but even low energy lighting systems can create relatively high energy demands. More so when the lighting is turned on and left on throughout the daylight hours irrespective of need where automated lighting controls have not been incorporated into the design.
Thermally efficient insulated rooflights can further reduce heat loss and energy consumption. The effectiveness of rooflights as a contributor to energy efficiency are acknowledged in the Building Regulations Approved Document Part L. It recommends that industrial and commercial building structures should have a rooflight area of 10% to 20%, subject to limiting solar gains. Research by De Montfort University and published by The Rooflight Association (RA) demonstrates the savings that can be made by increasing rooflight areas.
This graph demonstrates the reduction in CO2 emissions of a typical notional building as the rooflight area is increased to the optimum 16% to 18% and used in conjunction with a fully automated lighting control system.
Rooflights are a simple and cost-effective choice to introduce a more even and usable distribution of natural light, particularly in large structures where light is required deep into the building or in enclosed areas that cannot be lit through an external wall. Increased areas of light diffusing rooflights, often with lower light transmission or improved thermal performance, can optimise the energy performance of the building, and there are many permutations of performance to choose from. Reduced areas of rooflights with high light transmission levels and poor diffusion that create glare and hotspots, while still leaving areas of shadow and gloom that must be overcome with localised artificial lighting, only demonstrate poor consideration to the daylight design.
Another element to consider is a BREEAM assessment. Many local authorities now insist on this before they will give planning permission, therefore it is vital to optimise the rooflight design, distribution and product type. Using rooflights with low or reduced embodied carbon is a further example of good product selection that can have a significant effect on the BREEAM assessment.
Clients need to have buildings to meet the stringent regulatory requirements that will continue to tighten, or even exceed them.
Achieving a BREEAM rating of ‘Excellent’ as opposed to ‘Very Good’ can make a significant difference to the developer who is looking to let a large industrial or warehouse building to a prospective client.
Having a building that is lit by natural daylight will improve the efficiency, productivity, mental alertness and the general health of the occupants that work in the building.
In combination with good air-tightness and low fabric U-values, a reduction in the use of artificial lighting is the best way the building occupier can lower the energy cost of running the building.
When considering the design of a building it is now vital that rooflights, rather than being an afterthought, are treated as an essential design element right from the start.
Before the HSE introduced the CDM Regulations, they had already done some preliminary work on roof fragility. A simple ‘drop’ test onto a roof assembly was proposed, and if the impactor was retained, then the roof was deemed to be non-fragile. This testing, defined in “Special Inspectors Report No.30”, was then adopted as being the authoritative definition of non-fragility compliance.
The HSE subsequently recognised that SIR 30 test didn’t cover the full roof assembly or the interface between different components. It was open to variations in the interpretation of the results by those carrying out the testing. To improve the test, HSE carried out work to simulate the effect of a human falling on to a roof assembly, recording the impact loads applied. From this they determined that a 45kg sand bag, dropped from a height of 1.2m on to the assembly was typical of a human tripping and falling on a roof.
After several meetings involving all relevant roofing trade associations, the Advisory Committee for Roofsafety was formed and the first definitive guidance document produced; ACR(M)001:2000 Test for Fragility of Roofing Assemblies.
The Red Book
The industry is currently guided by ACR[M]001:2014 “Test for Non-Fragility of Large Element Roofing Assemblies” [fifth edition], known as the ‘Red Book’. It prescribes how a roof assembly should be tested to resist the impact of a person falling onto it, and then supporting their weight, clarifying how the assembly is then defined as ‘fragile’ or ‘non-fragile’, classified A to C. It is important to understand that the test is not of any single product, but all of the elements required of a correctly installed roof.
The impact testing is a ‘soft-body’ test specifically defined to concentrate a destructive load over a small area, at the most critical, worst case scenario locations of that assembly. Only by extensive testing for all failure modes can the tester gain a clear understanding of how and where the assembly will fail.
The application of this test and classification for in-plane rooflights is further defined in The Rooflight Association (RA) Technical Document NTD03, Application of ACR[M]001 ‘Test for Non- Fragility of Large Element Roofing Assemblies’ to GRP Profiled Rooflight Sheeting’.
Two factors impact on the period of non-fragility of roof assemblies:
quality and durability of the individual components.
quality of installation of the entire roof.
Manufacturers can only indicate the expected period of non-fragility based on extensive testing, and cannot offer performance guarantees on products not manufactured or installed by them. Further guidance is available from The Rooflight Association and The Metal Cladding and Roofing Manufacturers Association (MCRMA).
Imported GRP rooflight sheets claiming to be manufactured to UK recognised weights and specifications cannot be assumed to carry the same level of surface protection or achieve the same non-fragility ratings for the same periods if not compliant with the UK Annex to BS EN1013.
‘Walkable’ and ‘Walk-On’ Rooflights
Some built-up cladding systems incorporate a 0.70mm thick steel liner sheet in a profile depth usually exceeding 30mm. This liner assembly should be tested to achieve a non-fragile classification as a single skin only, to allow installers to safely traverse it while installing the cladding system – often referred to as a ‘walkable liner’.
It should be noted that profiled rooflight sheets in such an assembly, even though tested and demonstrated to achieve the required non-fragile rating, are still not ‘walkable’ and should never be subjected to foot traffic, regardless of specification.
Rooflights should never be walked on unless specifically designed and approved for this purpose. Irrespective of the strength of a rooflight and the non-fragility classification, foot traffic could damage the structural integrity or surface protection and consequently impact upon the long term performance of the product.
Rooflights designed to be walked on, and for use where they will be deliberately walked on, should be designed for much greater loads -the only suitable material is glass, subject to specific specifications for each application.
Polycarbonate and GRP should never be considered suitable materials for ‘walkable’ applications.
The need to produce energy-efficient buildings is, rightly, the key consideration in today’s sustainability-focused construction sector.
Saving energy reduces the carbon footprint and makes a vital contribution in the drive for carbon-neutral buildings. Equally importantly, it saves money by reducing the running costs of the operation of all buildings.
When considering large buildings, particularly in the metal shed sector, the traditional targets of improved thermal performance and minimised air-leakage have now reached their optimum performance levels. Put simply, they have reached the point of diminishing returns, with further increases in insulation delivering limited benefit.
Hardly surprising, then, that specifiers and clients are becoming focused on the significant contribution that can be obtained by designing natural daylight into buildings and seeking the best rooflight solutions to deliver this free resource.
Depending on the type of lighting system installed, the cost of lighting a building can be more than ten times the cost of the heat saved by removing the rooflights. In many building designs, the cost of the lighting can be four times that of the heat losses when ‘light to heat’ balance has been considered. Even with contemporary low energy LED systems, this ratio can still be as high as three times. So the daylighting plan now is becoming a principal consideration in the building envelope design and specification process.
To focus on this critical design aspect means that specifiers are now faced with a veritable haze of information regarding the choices they can make on rooflight specifications.
At this point, care is needed.
Like every other component within the metal building envelope, rooflights must perform several functions. Amongst other things:
Deliver good light transmission.
Not create excessive solar gains.
To deliver adequate heat retention.
Provide a non-fragile roof assembly.
Must deliver a well-lit building with the right kind of light.
Not all these requirements are complementary; it is important to strike the right balance for each building design, and understand that there is no ‘one size fits all’ solution.
Light, Thermal and Solar Transmission
It is equally important to understand that there are fundamental laws of physics that cannot be changed. In glazing and glass reinforced polyester (GRP) rooflight systems, most of the heat energy from the sun is transmitted directly and in the visible spectrum. Plastics such as polycarbonate have more energy transmission in the infra-red regions and beyond. This means that it is simply not possible to deliver any system with an achievable mix of high light and low solar transmission – or ‘g-value’.
Same is true for specifications which ‘cherry pick’ only some elements of a ‘holistic package’ design in isolation. In the right building, it is sometimes possible to use smaller areas of rooflights than would normally be considered adequate, but these would be designed and intended for use in conjunction with additional offsetting renewable energy sources. Even using rooflights that deliver exceptionally high light transmission levels, poor distribution – or inadequate areas of rooflighting – can create uneven and unsatisfactory levels of light balance within the building.
Similarly, whilst the improved thermal performance of rooflights can reduce heat loss, the inclusion of increasingly numerous ‘clear’ insulating layers or cells can be counter-productive. Each layer or cell adds an additional light reflective surface into the assembly. These cumulatively reduce the level of light transmitted into the building, costing more than the small savings in heat retention.
There is no trade-off on non-fragility. It’s about safety and saving lives, and no-one within the specification chain has the right to gamble with it. Rooflights can be made stronger by making the material thicker and more substantial, but in metal cladding systems, this can come at a cost; installation fit and weatherproof sealing becomes harder to achieve, but innovative reinforcement methods are now available delivering high impact and tear resistance in lighter thinner sheet formats.
Type of Light
Finally, we come to the question of which TYPE of internal illumination is best for the building. High levels of light streaming through small openings in the roof – no matter how well diffused – inevitably deliver a mixture of glare and gloom, further worsened by increased shadows created within the building by both the fixtures & fittings, and the occupants. Achieving a good ‘average’ level of daylighting within a building is very different to delivering a good, viable, uniform distribution of daylight that avoids the need for additional and localised supplementary artificial lighting. Glare and gloom can be significantly reduced by high levels of diffusion from internal surfaces and components within a rooflight.
Glass Reinforced Polyester (GRP), by its very nature, spreads daylight omni-directionally within the building and can also make a major contribution to internal illumination uniformity and comfort levels, but responsible specifiers must always recognise that diffusion alone cannot deliver the uniformity of lighting that is so often assumed or taken for granted.
So, whilst there are great savings and positive contributions to be made by incorporating rooflights into a building envelope, as with every specification issue, it is important to understand that there is the need to strike a real and meaningful balance between all of the performance characteristic options of the rooflight in order for the completed building to perform exactly as the specifier and the client intended. Getting this consideration wrong is not an option if you want to see your building in the right and best light.