Lisa Stephens, Product Manager at ROCKWOOL® UK, explores why future-ready homes demand insulation solutions that deliver more than just thermal metrics.

Designing insulation into the building envelope – walls, floors and roof – is an effective way to help improve the overall energy performance of a new home, but this is dependent on the quality of installation. While the insulation specification might indicate the expected energy performance, the ‘as-built’ result may differ – creating what’s often referred to as the performance gap.

Instances of poor detailing – such as gaps forming between insulation, lack of insulation and continuity at junctions, poor installation in lofts, debris and mortar snots in cavity walls, and incorrect positioning of windows and doors – all have an impact.

While a small gap might seem insignificant, evidence suggests that even air gaps as small as 6mm can significantly increase heat transfer and reduce overall thermal performance.

Changes to Approved Document L 2021 (England) aimed to close this ‘performance gap’ by requiring developers to provide photographic evidence at key stages of construction. This evidence should show that insulation has been installed continuously and without gaps, before these elements are concealed.

Ensuring an accurate and quality fit plays an important role in achieving this continuous insulation layer, but material choice also makes a difference when closing the performance gap.

Selecting a product

Achieving a precise fit and as-designed performance depends on the type of insulation used and selecting a product solely on its thermal conductivity overlooks this critical consideration.

Opting for pliable insulation can help achieve a tight, continuous fit efficiency, as it can be friction-fitted without extensive and precise cutting. More flexible insulation also allows for easier installation at the abutments between insulation boards.

To investigate the performance of stone wool insulation, ROCKWOOL conducted a study with the University of Salford Thermal Measurement Laboratory. The aim was to understand what happens physically when two pieces of ROCKWOOL insulation join.

Based on independently measured data from the University, ROCKWOOL concluded that when its stone wool slabs are tightly joined, the edges knit together. This provides a continuous insulating layer of trapped pockets of air, with no gaps and no associated loss of thermal performance.

Stone wool also maintains its shape and density over time – an important factor, since some insulation types can lose thermal performance due to loss of dimensional stability.

In tests on materials from real-life installations, it was found that stone wool can retain its insulating properties for more than 65 years without a drop in thermal performance.

A practical solution

With build programmes under pressure, there is a need for insulation systems that are straightforward to install and deliver consistent results.

For more information on closing the performance gap, read the ROCKWOOL Technical Bulletin

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Bradley Hirst, Technical Services Manager at Knauf Insulation, explores why insulation impacts indoor air quality more than you think.

With the Future Homes Standard on the horizon and the government’s stated target of building 1.5 million homes in the next five years, housebuilders are under pressure to deliver more for less. Insulation will play a key role in the drive to lower carbon emissions and energy costs. But the right approach to insulation also has other, sometimes overlooked, benefits – including helping to improve indoor air quality (IAQ). Housebuilders that understand this can differentiate themselves not just on lower running costs and improved comfort, but on occupant health.

Occupational hazards

To appreciate insulation’s role in IAQ, it’s important to first understand some common health concerns. Sick Building Syndrome (SBS) refers to a range of nonspecific symptoms, such as headaches or fatigue, that appear to be linked to time spent in a particular building. While poor air quality can be a contributing factor, SBS can also stem from other environmental issues like dust, lighting, or excessive noise.1

In contrast, Building-Related Illness (BRI) refers to health conditions caused by identifiable factors such as exposure to volatile organic compounds (VOCs) or mould spores.2 While the causes of SBS symptoms may be ambiguous, BRI is directly linked to a building’s environment – and housebuilders can take targeted actions to reduce the risks. There are three main factors that influence IAQ: the external environment, occupant behaviour, and the building’s construction. Outdoor air pollution can infiltrate buildings, while indoor activities like cooking, smoking, or owning pets can release pollutants. For housebuilders, the third factor is the most important, and that is the design and construction of the building itself. Building performance, and the materials used to deliver it, are crucial for managing air quality, reducing the risk of SBS and tackling the causes of BRI.

Ventilation, insulation and mould

One of the most visible and harmful indicators of poor IAQ is black mould, which thrives in damp conditions and can cause respiratory issues or aggravate allergies. High indoor humidity and poor ventilation will cause water vapour to condense on cold surfaces such as poorly insulated walls. This provides all the required conditions for mould to flourish – which can feed off any organic material including wood, dust particles, wallpaper, cardboard, cellulose or even gypsum board.

This is where insulation becomes vital. Well-insulated walls retain heat during colder months, reducing surface condensation and the likelihood of mould. However, insulation must be installed correctly to be effective. Any air gaps or discontinuities in the thermal envelope can lead to cold spots where condensation forms more easily. A continuous, properly installed insulation layer ensures surface temperatures remain consistent and discourages moisture build-up.

Ventilation works in conjunction with insulation to reduce mould growth. Without sufficient ventilation, even the best insulation can’t prevent poor IAQ. Effective systems, whether passive (like trickle vents) or mechanical (such as extractor fans), ventilate moisture-laden air to prevent the conditions that allow mould to flourish.

Construction products and VOCs

Building performance isn’t the only way housebuilders can improve IAQ. The materials used during construction can have an impact on indoor levels of VOCs – gases emitted from common construction products that can cause a variety of acute health symptoms for building occupants.3 By using products with low VOCs, housebuilders can help to mitigate some of the potential risks of harmful chemicals.

When choosing low VOC insulation, we recommend housebuilders look for Eurofins Indoor Air Comfort Certification. Eurofins Scientific has developed a European-wide standard for testing the VOCs emitted by consumer products, including building products. There are two certifications for indoor air comfort, ‘standard’ and ‘gold’. The latter is awarded to those products that go beyond legislated standards and contain no formaldehyde or phenols.

For example, Knauf Insulation’s glass mineral wool range uses ECOSE®, their unique plant-based binder that is low- VOC and contains no added formaldehyde. As a result, these products have been awarded Eurofins Gold Certification for indoor air quality.

Healthier buildings

By combining proper ventilation, low-VOC materials, and a continuous thermal envelope, housebuilders can reduce risks like condensation, black mould, and exposure to harmful chemicals. With growing demand for healthier, more sustainable homes, those who prioritise indoor air quality will be well-positioned to meet regulatory standards and exceed customer expectations.

More information on Knauf Insulation

Sources:

1 NHS website: Sick Building Syndrome

2 Design Buildings website

3 Environmental Protection Agency website

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Superglass, one of the UK’s leading glass mineral wool insulation manufacturers, is officially scrapping white pallets from its supply chain as part of its ambitious sustainability commitments by becoming an early adopter of the recovery, repair and reuse scheme, The Pallet LOOP.

From early April, Superglass’ cured glass mineral wool insulation products began to be distributed on The Pallet LOOP’s distinctive green pallets, which are designed to be collected and put back into the building materials supply chain again and again.

The Pallet LOOP, (part of BSW Group), is helping UK construction cut its consumption of timber for pallet production, reduce waste and improve its sustainability credentials. Every year, 20 million new pallets are manufactured for use in the sector, with most skipped or scrapped (~90%). The Pallet LOOP’s service-orientated model is shifting the dial on pallet waste, replacing the sale of traditional ‘white’ pallets with a range of reusable pallets that are typically up to 25% stronger than standard pallets and have a carbon footprint that is up to 40% lower. The Pallet LOOP also incentivises returns with a PayBack of up to £4 on every green LOOP pallet collected for reuse.

Superglass provides its products to homeowners, specifiers, housebuilders, installers and merchants. The firm’s manufacturing facility in Stirling is one of Europe’s most advanced, using lean production techniques to minimise waste and making insulation to order. Superglass glass mineral wool insulation products can save more than 200 times the energy typically used in creation and transportation. Additionally, the glass mineral wool insulation is made from up to 84% recycled glass content, has a BRE green rating of A+, and has no Ozone-Depleting Potential and Global Warming Potential. All Superglass products are also deemed non-combustible with a fire classification of Euroclass A1, which is the highest possible rating, when tested to BS EN 13501-1 reaction to fire.

Etex Group, which acquired Superglass in 2023, has also signed the United Nations Global Compact, prioritising its sustainable development goals (SDG) to meet targets set for 2030. Under the voluntary initiative, members commit to supporting a precautionary approach to environmental challenges, undertake initiatives to promote greater environmental responsibility and encourage the development and diffusion of environmentally friendly technologies.

Theresa McLean, Etex UK Insulation Leader, said: “Having the opportunity to reduce hundreds of tonnes of waste within our supply chain made joining The Pallet LOOP an easy decision for us. By partnering with The Pallet LOOP, we can, crucially, lower the amount of construction waste that goes to landfill.

“Schemes like The Pallet LOOP are vital for organisations like ours because they’re creating the kind of circular economy model that is urgently required to protect the planet, which is exactly what we’re committed to supporting as part of our sustainability efforts here at Superglass.

“We’ve always been a sustainably-minded organisation, committed to reducing waste and saving valuable resources, but as an industry, we can, and need to, do more. Joining The Pallet LOOP scheme is the perfect way for us to mark the start of 2025 as we continue to bolster our sustainability efforts throughout the year and beyond, while delivering excellent services to our customers across the UK.”

Paul Lewis, Founder of The Pallet LOOP, said: “We are delighted to welcome Superglass to The Pallet LOOP. The company’s decision to start transporting their insulation products on our green reusable pallets provides further evidence that The Pallet LOOP is the right thing to do for the construction industry, and the planet.

“It’s an exciting time for everyone linked with The Pallet LOOP. The number of green LOOP pallets being returned for reuse is increasing week on week and, as more green pallets enter the building materials supply chain this year, there will be even more opportunities for pallet recipients to save money, reduce waste and cut their carbon footprint.”

The Pallet LOOP operates a wide network of pallet manufacturing and pallet collection hubs in conjunction with Scott Pallets. Since its green LOOP pallets launched in May 2024, The Pallet LOOP estimates it has helped the construction sector reduce wood waste by around 9,500 tonnes. The use of its reusable pallets also means an estimated 13,077 cubic metres of timber has been freed up for other longer-term carbon storage applications*.

For more information, visit our dedicated Pallet LOOP page.

* Figures based on LOOP’s data tracker as of 6^th February 2025.

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Superglass, one of the UK’s leading glass mineral wool insulation manufacturers, is officially scrapping white pallets from its supply chain as part of its ambitious sustainability commitments by becoming an early adopter of the recovery, repair and reuse scheme, The Pallet LOOP.

From early April, Superglass’ cured glass mineral wool insulation products will start to be distributed on The Pallet LOOP’s distinctive green pallets, which are designed to be collected and put back into the building materials supply chain again and again.

The Pallet LOOP, (part of BSW Group), is helping UK construction cut its consumption of timber for pallet production, reduce waste and improve its sustainability credentials. Every year, 20 million new pallets are manufactured for use in the sector, with most skipped or scrapped (~90%). The Pallet LOOP’s service-orientated model is shifting the dial on pallet waste, replacing the sale of traditional ‘white’ pallets with a range of reusable pallets that are typically up to 25% stronger than standard pallets and have a carbon footprint that is up to 40% lower. The Pallet LOOP also incentivises returns with a PayBack of up to £4 on every green LOOP pallet collected for reuse.

Superglass provides its products to homeowners, specifiers, housebuilders, installers and merchants. The firm’s manufacturing facility in Stirling is one of Europe’s most advanced, using lean production techniques to minimise waste and making insulation to order. Superglass glass mineral wool insulation products can save more than 200 times the energy typically used in creation and transportation. Additionally, the glass mineral wool insulation is made from up to 84% recycled glass content, has a BRE green rating of A+, and has no Ozone-Depleting Potential and Global Warming Potential. All Superglass products are also deemed non-combustible with a fire classification of Euroclass A1, which is the highest possible rating, when tested to BS EN 13501-1 reaction to fire.

Etex Group, which acquired Superglass in 2023, has also signed the United Nations Global Compact, prioritising its sustainable development goals (SDG) to meet targets set for 2030. Under the voluntary initiative, members commit to supporting a precautionary approach to environmental challenges, undertake initiatives to promote greater environmental responsibility and encourage the development and diffusion of environmentally friendly technologies.

Theresa McLean, Etex UK Insulation Leader, said: “Having the opportunity to reduce hundreds of tonnes of waste within our supply chain made joining The Pallet LOOP an easy decision for us. By partnering with The Pallet LOOP, we can, crucially, lower the amount of construction waste that goes to landfill.

“Schemes like The Pallet LOOP are vital for organisations like ours because they’re creating the kind of circular economy model that is urgently required to protect the planet, which is exactly what we’re committed to supporting as part of our sustainability efforts here at Superglass.

“We’ve always been a sustainably-minded organisation, committed to reducing waste and saving valuable resources, but as an industry, we can, and need to, do more. Joining The Pallet LOOP scheme is the perfect way for us to mark the start of 2025 as we continue to bolster our sustainability efforts throughout the year and beyond, while delivering excellent services to our customers across the UK.”

Paul Lewis, Founder of The Pallet LOOP, said: “We are delighted to welcome Superglass to The Pallet LOOP. The company’s decision to start transporting their insulation products on our green reusable pallets provides further evidence that The Pallet LOOP is the right thing to do for the construction industry, and the planet.

“It’s an exciting time for everyone linked with The Pallet LOOP. The number of green LOOP pallets being returned for reuse is increasing week on week and, as more green pallets enter the building materials supply chain this year, there will be even more opportunities for pallet recipients to save money, reduce waste and cut their carbon footprint.”

The Pallet LOOP operates a wide network of pallet manufacturing and pallet collection hubs in conjunction with Scott Pallets. Since its green LOOP pallets launched in May 2024, The Pallet LOOP estimates it has helped the construction sector reduce wood waste by around 9,500 tonnes. The use of its reusable pallets also means an estimated 13,077 cubic metres of timber has been freed up for other longer-term carbon storage applications*.

For more information about Superglass, visit: https://www.superglass.co.uk/.

* Figures based on LOOP’s data tracker as of 6^th February 2025.

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James Francis, Product Manager at ROCKWOOL UK, explains why insulation choice isn’t just about U-value.

In the past, selecting insulation was a straightforward task of choosing a product that meets the required Uvalue. However, as thermal performance requirements become more complex, it’s crucial for housebuilders to specify based on more than just one metric.

The importance of installation
During installation, common mistakes that can affect the long-term energy performance include gaps forming between insulation, lack of insulation and continuity at junctions, poor insulation installation in lofts, debris and mortar snots in cavity walls and incorrect positioning of windows and doors.

While a small gap might seem insignificant, tests by the BRE in 2008 on sample houses showed that features associated with poor workmanship could, in some cases, cause the U-value to rise as much as 310%. Likewise, a study by Belgian professor Lecompte from 1990 found that an air gap as small as 6mm is enough to increase heat transfer by 158% of the design value.

These studies highlight the importance of fitting insulation effectively, but achieving a quality installation that will perform long into the future starts with the specification.

Starting with specification
As Approved Document L (ADL) 2021 (England) advises, continuity is crucial when it comes to insulation that calls for a tight and continuous fit with minimal gaps. Yet the ease of achieving this level of precise fit and the time needed to achieve it vary depending on the type of insulation used.

As part of ADL 2021, there is now a requirement for photographic evidence at various construction stages before elements are concealed. For insulation, developers will need to provide proof of the thermal continuity of the material at foundations/structures, external walls, roofs, openings, pipes, and ducts. This evidence should demonstrate that the material is fitted tightly and without gaps.

While continuity is already best practice for installation, there’s now even more pressure on developers to achieve a tighter, continuous fit, which could require additional cutting on-site and/or taping at board joints with foil tape. For housebuilders acutely aware of build schedules, this requirement could equate to extra time completing a plot and a more significant burden to ensure building control sign-off.

Why insulation choice matters
The ease of achieving this level of precise fit and, in turn, as-designed performance varies depending on the type of insulation used and selecting a product solely based on its thermal conductivity, overlooks this critical consideration.

Pliable insulation can help achieve a tight, continuous fit efficiency as it can be friction-fitted without extensive and precise cutting. Opting for more flexible insulation allows for easier installation at the abutments between insulation boards, another area prone to thermal leakage.

Specifiers also need to think longer term as the thermal performance of some insulation types can diminish over time due to loss of dimensional stability. Choosing a product that retains its manufactured dimensions long-term means the material will not shrink or warp when exposed to high temperatures or humidity and, in turn, create gaps between the insulation and the substrate.

We also recently completed a study with the University of Salford Thermal Measurement Laboratory to investigate the performance of stone wool insulation. The aim was to understand what happens physically when two pieces of ROCKWOOL insulation join together and what impact this has on thermal performance.

Based on independently measured data from the University of Salford, we concluded that when our stone wool slabs are tightly joined together, the edges knit together providing a continuous insulating layer of trapped pockets of air with no gaps and no associated loss of thermal performance.

What’s more, stone wool has also shown its ability to maintain its shape and density over time. In tests on materials from real-life construction sites, we found that stone wool can retain its insulating properties for more than 65 years without a drop in performance.

By evaluating the performance of insulation based on additional factors, including longevity and ease of achieving a precise fit, housebuilders can build homes efficiently and deliver homes with thermal performance that is proven to last.

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As the uK’s weather becomes increasingly unreliable, with warmer summers and colder winters, should new build insulation prioritise thermal efficiency or summer comfort? Mark Cooper, uK and ireland sales manager at Actis insulation explains that the two may not be mutually exclusive.

With the effects of climate change increasingly impacting day to day life, new homes need to be built not only to be as energy efficient as possible, but also to withstand the effects of extreme heat.

On the one hand, Building Regulations legislate that carbon emissions for new builds need to be reduced by around a third over previous levels, while on the other they oblige architects to limit unwanted solar gains and provide a way to remove heat from residential dwellings. And while some of the latter can be achieved with strategic siting of windows, and even the use of brise soleils, housebuilders and architects can go a long way towards ticking both boxes by specifying the correct form of insulation from the get-go.

The idea of using insulation to deflect, as well as retain heat, is perhaps counterintuitive. But the canon of products developed by pan-European insulation specialist Actis is designed to meet the requirements of both Part L (conservation of fuel and power) and Part O (overheating) in the same quick, clean and easy to use package!

Reflective power
It’s well documented that homes insulated with traditional products, designed purely to protect the occupants from winter cold, can be insufferably hot in the summer. But reflective insulations, such as those designed by Actis, have the added bonus of preventing overheating – helping protect the health and comfort of the occupants.

Indeed, its two-in-one Eolis HC reflects 95% of infrared radiation while its wellestablished Hybrid range has also been specifically designed to help buildings stay cool, as well as warm. Interesting information on both thermal efficiency and the use of insulation in helping keep buildings cool is provided via Actis’ popular RIBA – approved CPDs, which have been immensely popular with builders, specifiers, architects and building control officers over the past few years, with thousands of construction Mark Cooper UK and Ireland sales manager at Actis Insulation professionals finding them invaluable as they wrestle with the complexities of ensuring a thermally efficient new build or conversion.

Tomorrow’s Insulation Solutions for Future Homes Standards and Addressing the Performance Gap with Reflective Insulation include information on thermal modelling psi values to calculate heat loss at junctions, the provision of construction details at both design and as built stage, the replacement of SAP methodology with the Home Energy Model (HEM) to calculate energy efficiency, and key aspects of the consultation on The Future Homes Standard.

Tomorrow’s Insulation Solutions for Future Homes Standards gives guidance on how to meet energy efficiency targets which see new build homes having to reduce carbon emissions by 31% over previous levels, while Addressing the performance gap with reflective insulation looks at how to achieve asbuilt performance.

Real-life application
Architectural designer Stuart Ellis, whose Actis-insulated conversion was featured on George Clarke’s popular Remarkable Renovations TV show, says: “Using Actis products is the thinnest way to achieve the desired U-values – and it’s really easy to fit.

“There’s also less waste than PIR board, which has the added benefit of taking up very little skip space. “I specify for a lot of listed buildings, which are really cold, so I build a stud wall inside into which to put the insulation. Obviously, I need to ensure the building is correctly ventilated to avoid condensation so external air bricks can be added to ensure the stone can still breathe. “I believe this is the way forward for listed buildings.”

And Kent builder Alan Downes, who has been using Actis products for the past five years, says of Eolis HC: “It’s an excellent product to install and saves huge amounts of time. I particularly like the large overlap in the surface of the product, which means the joints are much smoother for final plaster boarding.

It also increases U-values to meet current regulations. “The thing that makes Eolis especially good is its flexibility and the ease of installation, particularly over pitched roof angles, allowing for a really professional seal of insulation across the roof space.”

U-value benefits
In the winter months the benefit of the Uvalues achieved by using the Hybrid range and Eolis HC come to the fore – by meeting or exceeding required targets depending on the combination used. They’re also ideal in ensuring homes benefit from the maximum possible living space. Because they’re thinner, less of the wall or roof area is taken up with physical insulation – but with the same, or better, thermal efficiency than a traditional alternative.

Actis products are particularly popular with timber framers who can ensure consistent thermal quality across all their homes – and benefit from a much speedier installation process. The systems typically take between 25 and 50% less time to install than traditional alternatives.

Derek Dawson, MD of one such manufacturer, Scandia-Hus, which has used Actis in all its show homes says: “All products have been designed to eliminate thermal bridging by helping to ensure an airtight envelope. The range can achieve the highest U-value requirements with a minimal thickness.”

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Ken O’ Neill, offsite business development manager for Sto, discusses the benefits of marrying offsite construction with external wall insulation (EWI) and how collaboration is boosting efficiency.

As the urgent need to build more homes increases, offsite construction has a key role to play. Prefabricating components and structures in a factory enables homes to be delivered more quickly and with greater control. Quality can increase as can efficiency, safety standards and sustainability credentials.

To maximise the benefits of prefabrication, collaboration with specialist manufacturers will ensure systems used in the process meet developers’ specific needs while keeping production schedules on track.

Raising standards
Highly versatile, external wall insulation and rainscreen cladding (RSC) systems are ideal for off-site construction. They can be factory applied to a wide range of structural panels, including timber and steel framed structures. Once the EWI or RSC is installed, a wide range of façade finishes can be achieved using render, colours and textures, and brick slips.

Engaging with an EWI manufacturer in the project’s early design stages will ensure the most appropriate system is prototyped and developed. The substrate build-up and the components needed to meet the project’s specific performance requirements such as thermal efficiency and aesthetics must all be considered. These components must work together as a system otherwise it may not perform as expected once installed or meet Building Regulations. For this reason, it is strongly advised to work with a single supplier and avoid changing the design or substituting products at a later point in the process.

In line with this need, manufacturers are developing components offering cost and productivity benefits too.

After the design has been established, an experienced EWI manufacturer will be able to provide technical guidance and support in advance of any testing throughout the production process.

A manufacturer’s expertise will also help to ensure the installation of the modular wall panels runs smoothly on site. Bespoke method statements can be developed providing guidance on the most effective and efficient process for applying the EWI or RSC system.

Driving efficiency
Thanks to ongoing research and development, specialist products have been designed to further increase productivity. These include adhesives and base coats which dry much quicker than standard products used on site.

A further benefit is that these products can be delivered to factories in bulk quantities using silos with spray machines. These enable up to 1,000 kg of the adhesive and base coat to be directly sprayed onto the modular panels enhancing productivity.

Prefabrication partners
With the potential to deliver a significant proportion of new homes, off-site manufacturing will continue to grow. Specialist manufacturers are ideally placed to respond through innovative products and technical expertise. As a result, modular developers can benefit from tried and tested façade solutions and more streamlined production processes.

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Paul Barrett, head of product management at Rockwool UK, explains why housebuilders need to think differently about insulation to meet legislative and buyer demand.

Historically, choosing insulation has, broadly, been a box-ticking exercise; select the product that meets the required U-value and move on with the development. However, thermal performance requirements are evolving, and so too are buyer demands for insulation with a desire for more than just thermal capabilities.

Legislative drivers

One of the drivers for this shift is Government legislation. This month (June 2023) sees the transitional arrangements for Approval Document L (ADL) end, meaning all building works in England that start after mid-June must now meet the latest regulations.

As part of ADL 2021, there is greater scrutiny of the gap between designed and as-built performance. Now, on completion of work, a Buildings Regulations England Part L (BREL) report and photographic evidence are needed. This evidence will be provided to the building control body to demonstrate compliance with energy efficiency requirements. Photographs must be taken at various construction stages before elements are concealed to show build quality and that the designed details have been followed.

This means developers, and for insulation specifically, will need to show evidence of the thermal continuity of the material at foundations/structures, external walls, roofs and openings, pipes and ducts to demonstrate it is fitted tightly and without gaps.

While already best practice for installation, the need to physically evidence continuity increases the need to achieve a tighter, continuous fit and could require additional cutting on-site and/or taping at board joints with foil tape. For housebuilders acutely aware of build schedules, this requirement could equate to extra time completing a plot and a more significant burden to ensure building control sign-off.

The ease of achieving this level of precise fit and, in turn, as-designed performance varies depending on the type of insulation used and selecting a product solely based on a single metric, such as its thermal conductivity, overlooks this critical consideration.

For example, pliable stone wool insulation is simple to closely friction fit without impractical levels of precision cutting when on site. As well as minimising the margin for error, it also supports reliable and effective thermal performance that reduces thermal bridging. Further, the flexibility of stone wool allows for easier installation at the abutments between insulation boards, another area prone to thermal leakage. Plus, its composition means individual slabs knit together to create a seamless fit, and its workable nature supports the delivery of designed U-values.

Performance in-use

The shift to consider longer-term, post-occupancy performance brought about by ADL is also a trend that’s likely to continue as legislation such as the Future Homes Standard comes into law. Reports such as that from the Committee on Climate Change also reference the role of smart meters and their ability to ‘track progress in, and performance of, energy efficiency and heating measures.’

Whether in the future, housebuilders may have greater accountability for a home’s energy performance once in use remains to be seen. Still, there is decidedly a shift in buyers’ considering a home’s energy performance and its impact on their future bills. Equally, several major housebuilders are marketing the ongoing energy bill savings that buying a new home can bring.

When selecting insulation, it pays to have longevity in mind as the thermal performance of some insulation types can wane over time. For insulation to be effective – and remain so – dimensional stability is vital as the air pockets within it help prevent heat transfer. Squashed and sagging insulation can affect these energy-saving capabilities.

To prevent this, it’s essential to choose a product that’s going to keep its strength and, in turn, its thermal performance. Stone wool is ideal for this as it maintains its shape and density over time. In tests on materials from real-life construction sites, it has been shown to retain its insulating properties for more than 65 years without a drop in performance. Plus, because of its high-density semi-rigid composition, it will not slump in the cavity.

Buyer demands

As well as greater awareness of energy performance – our research found that energy efficiency ratings are important to 76% of consumers when buying or moving home –  consumers are also more discerning regarding new build quality. This greater scrutiny and a competitive housing market for attracting buyers mean that housebuilders need more differentiation than ever; an area where insulation can support them.

Following the Grenfell disaster and the subsequent ban on combustible materials in relevant buildings above 18 metres in England and Wales and 11 metres in Scotland, there is growing public recognition of building fire performance. As such, providing surety on fire resistance, even in low-rise housing, could help developers offer an additional marketable benefit. Manufactured from naturally occurring volcanic rock, stone wool has a natural, innate non-combustibility, with many stone wool solutions achieving a European Reaction to Fire Classification of A1 – the highest possible rating.

Similarly, stone wool provides acoustic performance due to a non-directional fibre orientation and increased density that traps sound waves and dampens vibrations, significantly reducing noise between rooms and from outside sources.

By considering insulation as much more than just a thermal insulant, housebuilders can achieve greater standout and improve the overall quality of their developments for buyers and years to come.

 For more information, go to www.rdr.link/xxx

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Rockwool’s NyRock Rainscreen 032, a stone wool insulation product, has been accredited with a BBA certificate.

Named after its low U-value of 0.032 W/mK, the product was developed for use within ventilated cladding systems, as well as sealed systems such as curtain walling.

According to Rockwool, NyRock Rainscreen 032 has a more efficient fibre structure that increases the density of air pockets trapped within each slab and so boosts its thermal performance. It has proven acoustic benefits and is water repellent, yet breathable. 

The post Rockwool | Weather shield appeared first on PHPD Online.

Minimising gaps in a building’s fabric delivers many benefits, from reduced heating costs to improved acoustics, comfort levels and occupant well-being. But what does the term airtightness actually mean? Chris Roughneen, Technical Manager at Isover examines the issue.

Ensuring a new home has a reasonable level of airtightness is essential to improve the energy efficiency of the building, which in turn will provide future occupiers with a comfortable environment to live in and reduced energy bills. Even the most well-insulated home will lose heat if airtightness levels are not addressed – it’s similar to filling a bath, without putting the plug in. In fact, poor airtightness can be responsible for up to 40% of heat loss from buildings.

But what is it? Airtightness is the measure of uncontrolled ventilation through gaps and cracks in the building envelope and it is vital that this is minimised, to ensure occupant comfort and wellbeing. In the UK, the level of airtightness is measured as air permeability in the unit m3/h.m2 at 50Pa (q50). This value refers to the volume of air in m3 that can flow per hour through each square metre of the building envelope at a pressure differential of 50 pascals.

Measurements
Within the Building Regulations, energy efficiency targets for new dwellings are key; providing an airtightness value for a guideline ‘notional building’ as well as an absolute limit. In England and Wales, the limiting value stated in Part L1A of the Building Regulations is 10 m3/h.m2 at 50Pa, whereas the value applied to the notional building within SAP is 5 m3/h.m2 at 50Pa. This means that there is a case for aiming for an improved level of airtightness to make SAP compliance easier.

In Scotland, the term Infiltration Rate is used instead of Air permeability, but the limiting factor is the same as it is in England and Wales. However, the value applied to the notional building within SAP is slightly different at 7 m3/h.m2 at 50Pa rather than 5 m3/h.m2 at 50Pa. To demonstrate compliance with these standards and regulations, a number of ‘as-built’ properties must be tested, and the actual number of properties that require testing is governed by the overall size of a development and the number of different building types situated within it.

With the above regulations in mind, it is highly recommended that airtightness levels and ventilation are carefully considered at the beginning of a project. Airtightness is achieved by designing and installing a continuous air barrier around the heated volume of the building. This air barrier will normally be on the warm side of the insulation. The junctions between different materials in the air barrier should also be well sealed and penetrations should be minimised and thoroughly sealed where they cannot be avoided.

Ventilation strategy
The ventilation strategy must also be considered at the same time as airtightness levels: too much air leakage leads to draughts, heat loss and wasted energy, whereas too little air infiltration can result in inadequate ventilation and poor indoor air quality. According to the Energy Saving Trust, the total ventilation rate for a home should be between 0.5 and 1.5 air changes per hour. This includes controlled and uncontrolled ventilation.

As such, the correct specification (and subsequent installation) of an airtightness management membrane is key. A traditional vapour control layer (VCL), such as a polythene sheet, can create an airtight finish, however, in practice, it can be very difficult to achieve a good installation on-site.

However, Isover’s new Vario system has been designed to make the installation as fast and easy as possible. In particular, the Vario XtraSafe has a unique adhesive ‘hook and loop’ fixing system, which means that a single contractor can effectively install the membrane on site.

The membrane is semi-transparent and pre-printed with 100mm squares to help with cutting and gauging overlaps for ease of placement, which further boosts the speed of installation.

In addition, the Vario XtraSafe system includes a wide range of accessories to help ensure an airtight seal around edges and penetrations such as windows, pipes, cables and sockets.

By designing in airtightness at the beginning of a project, housebuilders can rest assured that they have delivered an energy efficient home that will provide occupiers with a comfortable environment to live, work and play in, while improving their well-being.

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