Vertical Opportunity with Creative Structural Integrity
The Betoconcept range of earth retaining walls from Grass Concrete Ltd combine both structure and aesthetics.
This hospital re-development featured a number Betoconcept earth retaining walls.
One was a challenging construction, requiring a 4-metre-high wall, which had to work around contiguous concrete piles and incorporate a footbridge link to the main building. With a limited width available, the piles were clad vertically with stone finish Leromur blocks which transitioned into an inclined planted Betoatlas structure.
H+H’s unwavering commitment to energy-efficient building solutions and a fabric first approach aligns neatly with the aims of the Future Homes Standard.
A fabric first approach will be fundamental to meeting the requirements of the 2025 Future Homes Standard, for which the government published its consultation on 13th December 2023. Backed by a commitment to energy efficiency and reducing the carbon emissions of new homes, the consultation on the Future Homes Standard suggests u-Value for walls remains at 0.18W/m2K and that new homes will use low-carbon heating and be ‘zero-carbon ready’.
This methodology prioritises minimising heat loss by ensuring the building envelope meets the highest standards. To put it simply: housebuilders will need to pursue a fabric first approach by specifying high performing fabric materials from the outset.
Project 80
H+H is proud to have been involved in Project 80, a pioneering development by Midlands Heart Housing Association, which showcases homes already built to the Future Homes Standard using aircrete. These homes, monitored and evaluated for performance, demonstrated a 70% carbon reduction when combining heat pumps and PV panels in masonry structures.
Insights gleaned from Project 80 are invaluable, offering a blueprint for achieving an impressive 80-90% carbon emissions reduction. Increased insulation, enhanced window specifications, improved airtightness, and strategic education on effective heating and ventilation are just some of the strategies identified.
H+H’s participation in Project 80 is a testament to its dedication to a fabric first approach. H+H aircrete blocks contribute to the construction of energy-efficient, airtight buildings, enhancing the performance of technologies like underfloor heating and air source heat pumps. These innovations were integral to the success of the first 12 homes in Project 80.
H+H fabric first projects
H+H has a track record of working collaboratively to help developers achieve ever higher fabric performance standards, including projects which also employ Modern Methods of Construction. For example, the Cameron Close Passivhaus development for Southern Housing and the Norton Farm development for Bromsgrove District Housing Trust.
For the Cameron Close development of 16 semi-detached Passivhaus homes on the Isle of Wight, H+H worked with the scheme’s developer on the application of Thin-Joint blockwork. In this instance, H+H’s 200mm thick Celcon Plus Blocks have been used to construct Thin-Joint aircrete, load-bearing walls. Apart from accelerating the construction process, the Thin-Joints play a role in enhancing the residences’ airtightness, thereby improving their overall energy efficiency.
At the Norton Farm development, H+H’s Vertical Wall Panels have been used to speed the construction of the building’s energy efficient fabric. H+H’s Vertical Wall Panels, part of its i-House MMC system, have been used to construct 164 units.
The Vertical Wall Panels are manufactured in aircrete to the storey height of a standard house. Use of the Vertical Wall Panel system on this project enables the external brick or rendered-block facade to be taken off the critical path. More importantly, the Vertical Wall Panel system is a key element in creating an insulated, airtight building envelope.
As we approach the 2025 Future Homes Standard, adopting a fabric-first construction philosophy, supported by materials like aircrete, will pave the way for sustainable, low-carbon housing.
H+H Vertical Wall Panels represent a masonry MMC solution that provides the speed of offsite with the familiarity of a traditional build. Offering the ability to construct a complete house shell in just five days, these storey-high panels of aircrete are used to form the inner leaf of external walls, separating walls and internal partitions.
Fabricated offsite, the panels are craned into place for an accelerated construction process that retains the reassuring characteristics of a high-performance masonry build.
On site, Vertical Wall Panels are placed onto standard foundations and installed using H+H VWP mortar – a fast-setting and very strong mortar that forms a 2mm airtight joint.
The overriding advantage of Vertical Wall Panels is the speed of build – and this is best demonstrated where the panels are used as part of a complete housebuilding package.
When combined with prefabricated timber floors and a prefabricated roof system, Vertical Wall Panels provide a system-build solution that can construct the superstructure of a house from foundation to roof within five days onsite.
This provides a watertight and airtight shell for follow on trades to move into, and one which is constructed using a material they are familiar with so no additional training is required for site workers.
Offering flexibility and durability
Aircrete is a lightweight masonry material, combining proven durability and high acoustic, thermal and airtight performance with the ease of use that comes with a lighter material making it easy to cut and work with.
H+H Vertical Wall Panels are manufactured in a range of heights with a width of 600mm and a thickness of 100mm. As aircrete can be cut on site, it is easy to accommodate window and door openings while providing infill sections as appropriate. This also gives the flexibility needed to adjust panels to cope with site tolerances and onsite modifications and means less product waste on site.
Tried, tested and proven
Building with H+H Vertical Wall Panels is not a new solution. In fact, the system has already been widely used across Europe for years and over 2,000 houses have been completed so far in the UK.
It is also an established Modern Method of Construction recognised by the NHBC. The system is part of the NHBC Accepts scheme which recognises innovative building systems that have been rigorously tested to meet the construction body’s stringent standards.
H+H Vertical Wall Panels combine the cost benefits associated with offsite construction with the reassuring familiarity and performance of masonry, offering an MMC system that will stand the test of time.
With buyers willing to pay more for efficient homes, using H+H Celcon Blocks Solar Grade for wall building makes more sense than ever.
Energy efficiency is fast becoming one of the most desirable features of a new home, and one that homebuyers are willing to pay a premium for.
A new survey from Samsung[i] of 1,000 adults looking to move home in the next five years found that almost three quarters (71%) said energy efficiency is a key factor when considering a home and more than half (56%) say it will save them money.
Santander[ii] reported in October 2022 that buyers are paying an average of 15.5% more for a home that meets high energy efficiency standards, with over one third of estate agents reporting that buyers will pay a 20% premium in their area.
For most homebuyers, understanding the energy efficiency of a prospective new home will be done via energy rating systems like EPCs (Energy Performance Certificates). Installing new technologies like PV panels and air source heat pumps will of course impact these ratings. But the building fabric also has a major influence on a dwelling’s EPC rating.
Housebuilders looking to benefit from the higher prices commanded for ultra energy efficient homes need to be taking a fabric first approach. The significance of this has become even more apparent in the 2021 update to the Part L of the building regulations. The changes placed an increased emphasis on building fabric performance and ensuring the precise construction of thermal bridges and junctions.
As better insulation and more efficient heating systems are built into the design of new homes, heat loss from the building envelope becomes increasingly significant in contributing to the overall heat lost from a building. Therefore, getting energy efficiency right in the building fabric is key.
Any H+H aircrete product possesses impressive thermal qualities and can achieve excellent airtightness when used in wall building. H+H Celcon Blocks Solar Grade take efficiency even further however, having been specially engineered to offer enhanced thermal performance over our standard grade aircrete products.
H+H Solar Grade Blocks have a thermal conductivity of 0.11 W/mK and compressive strength of 2.9N/mm2, making them ideal for achieving ultra-low wall U-values in one or two storey dwellings.
It’s clear that building energy efficient homes pays, and using H+H Solar Grade Blocks is an ideal way to ensure low carbon living starts with the building fabric.
There are wide ranging benefits to using aircrete foundation blocks as a groundworks solution, including helping to meet Part L.
Housebuilders are increasingly turning to aircrete foundation blocks for a simplified and cost-effective method of DPC construction.
Weighing just one third of an equivalent dense aggregate block, aircrete is relatively faster and easier to lay. In addition, only a single leaf of blockwork needs to be laid to form the foundations, as opposed to cavity construction which requires two leaves of blockwork and concrete infill. This means works can be completed in less time, reducing labour costs.
Aircrete is a high-performance material that helps housebuilders construct energy efficient homes that easily meet building standards. H+H Foundation Blocks, for example, can help to enhance a dwelling’s energy efficiency by reducing heat lost into the ground while reducing the need for additional insulation.
Aircrete’s material properties mean it’s highly thermally efficient and able to achieve low U-values which makes meeting the standard set out in Approved Document L easy.
In fact, as new building regulations increase emphasis on building fabric and thermal bridging, aircrete is a preferred material and this can include its use in foundations.
The 2021 amendment to Part L recommends using aircrete foundation blocks where aircrete is being used in the construction of external walls to ensure continuity of insulation levels within the building fabric.
Despite being one of the lightest forms of masonry, foundations built with H+H aircrete are fully load-bearing. H+H Foundation Blocks Standard Grade are suitable for housing up to two storeys high. For three storey buildings, H+H offers High Strength Grade Blocks which have a compressive strength of 7.3N/mm2.
For further information on H+H Foundation Blocks and our products visit www.hhcelcon.co.uk
Jenny Smith-Andrews, Head of Marketing at aircrete manufacturer H+H, outlines the arguments for a building method that focuses on the long term.
Aircrete makes the perfect structure for certified Passivhaus homes
The arguments around what constitutes sustainable building practice continue to shift focus. Back in 2007 the emphasis was on zero carbon in use for new homes. In 2022 much more attention is being placed on embodied carbon and the race is on for manufactures to decarbonise their businesses.
Both objectives are hugely important, of course, and H+H has demonstrated its ability to deliver on the first and now has a robust plan to deliver on the second. However, we would argue that there is an important third: the need to consider the long term.
It has always seemed strange to me that there is so little attention paid to how long a building should be expected to last. Most guidelines seem to anticipate a sixty year design life but surely this is insufficient?
Replacement rates
Stone clad to suit the local style, these houses are based on modern Thin-Joint construction
In the UK we demolish about 9,000 homes per year. If we continue to replace the current housing stock at this speed, we would need every house built today to last not sixty years but several hundred.
This is not new information, but in this context it is odd that lightweight housebuilding systems are encouraged, based on their ability to meet speed of build and energy efficiency standards, with no apparent focus on longevity.
The crunch may come with the financial model. With house prices in 2021 averaging £198,000, mortgage finance is essential for most first-time buyers, and the length of available mortgage terms is rising.
Mortgage terms and housing durability
this new home, built with underfloor heating and an air source heat pump is a glimpse of the future.
The English Housing Survey finds that 45% of first-time buyers in 2018-2019 had a mortgage of 30 years or longer and 40-year mortgages are becoming increasingly common. 2021 saw one company launching a 40-year fixed term mortgage.
What this essentially means is that to be attractive to buyers your home needs to be pretty sure to have a service life comfortably longer than a normal mortgage term.
Not surprisingly, H+H has always argued that masonry homes, designed to last for one hundred plus years, are the best long-term option in terms of financial security. We would also argue that the most sustainable homes are surely those which last a very, very long time.
Meeting the immediate
a modern material to last for centuries
Right now, with the pressure to increase the volume at which we build new homes, the priority for builders is to ensure that familiar building methods can meet current building standards.
The latest collaborative project to involve H+H aircrete is Project 80, a research project designed to demonstrate how masonry building methods will meet the Future Homes standard, requiring a reduction of 75% – 80% over current building regulations.
Sustainable building – a holistic view
The arguments around what constitutes sustainable building will continue and the wisest course is surely not to focus on one performance aspect in isolation but to consider the bigger picture and take a holistic view.
For H+H this means building energy efficient homes whose creation involves the minimum possible immediate environmental impact and which will continue to provide a resilient, dependable asset for generations.
To find out more about aircrete from H+H, visit our website at www.hhcelcon.co.uk
Jenny Smith-Andrews, Head of Marketing at aircrete specialist H+H UK Ltd outlines the sustainability arguments for masonry buildings
H+H has always seen itself as a manufacturer that supports sustainable building – but over time, the definition of the term and priorities for the building industry have shifted. It is good therefore to see some consensus emerging on the objectives for sustainability and how each industry can meet them. H+H supports the principles set out in the UN Sustainability goals and is committed to supporting this agenda.
Reducing carbon
The first, and increasingly urgent, priority is to reduce carbon emissions. When it comes to housebuilding that means a focus on reducing the energy demand of our homes. Home heating alone contributes around 19% of the total CO2 produced in England each year so it is logical that building regulations and the Future Homes Standard are looking to increase further the thermal efficiency of new buildings.
Aircrete has a part to play in this agenda. With its inherent thermal efficiency and very effective airtightness, the material has always been a good choice for energy efficient homes. In fact, H+H was involved well over a decade ago in the development of prototype zero carbon homes.
More recently, aircrete has been used as the foundation of low energy homes for social housing schemes where fuel costs are a primary concern and Passivhaus designs offer a practical solution.
When it comes to revisions to Building Regulations Part L, aircrete is well suited to the newer, more stringent standards and a familiar cavity wall construction will meet all the revisions currently planned.
Operational zero carbon is only one part of the story, however, and attention is increasingly focused on embodied carbon. Moving to net zero manufacturing is challenging and requires the whole supply chain to be working to the same goal.
H+H has published its roadmap to zero carbon, outlining a journey that will decarbonise its manufacturing and transport processes. However, even in this objective there can be a degree of interpretation and different measurement techniques.
Our response is to use robust lifecycle analysis methods including all the manufacturing, in use and post-use phases of construction. It is essential to develop commonly agreed standards for calculation to provide a level playing field and ensure that all manufacturers are basing their claims on equivalent data sets.
In its planned journey to zero carbon by 2050, H+H is relying on science-based targets to provide a benchmark against which to measure progress.
A Sustainable future
Low carbon construction is the focus at the moment, but at the same time, lifespan and resilience of new homes must form part of a sustainability strategy.
There is little point in reducing manufacturing carbon if the resulting building only lasts for a few decades and then needs to be entirely replaced. There is an increasingly significant school of thought suggesting that the most sustainable building is one that will last a very, very long time.
And during its lifetime, the building will need to withstand the extremes of a changing climate. In its June 2021 Assessment of UK Climate Risk, the Committee for Climate change cited overheating and flooding as the two most significant risks for the housing sector.
H+H would point to the 150-year lifespan, inherent resilience and thermal mass characteristics of aircrete to further support its position as a material with a secure future in modern, sustainable housing.
For further information on H+H, its products and its sustainability criteria, go to www.hhcelcon.co.uk
Concrete blockwork remains one of the most cost-effective methods of controlling airborne sound, making it a natural choice for constructing partition and separating wall. Meeting sound insulation standards is a key requirement for most building types.
Standards
The acoustic standards contained in Part E of the Building Regulations have been in force since 2004. They cover a number of building types including flats and apartments, semi- detached and terraced housing, hotels, hostels, nursing homes and student accommodation. These Standards do appear to be effective in eradicating noise complaints and thus achieving a better quality of life for building occupants.
Sound performance targets, particularly those limiting sound transfer between adjoining dwellings, are specified in Approved Document E1 to the Building Regulations. For separating walls and floors in attached houses or apartments, the airborne performance to be met is 45 dB DnT,w + Ctr (or 56 dB DnT,w in Scotland).
This performance is applicable to sound frequencies from 100 Hz (low frequency) to 3150 Hz (high frequency).
Achieving enhanced levels of sound insulation
There is often a requirement for walls non-domestic buildings, to achieve a higher level of sound insulation. Commonly the performance of building elements, will be described as a weighted sound reduction index, Rw. This term describes the airborne sound insulating power of a building element. It is a laboratory-measured value as defined in ISO 717: Part 1. It can apply to walls, ceiling/ floors, ceiling/roofs, doors, or windows. The higher the number, the greater the sound insulating power of the building element. It is measured over the frequency range 100 to 3150Hz. Depending on its composition and density, and any applied finishes, standard blockwork construction can provide an Rw of up to around 57dB. An example of a higher performing construction is the use of a 215mm Lignacrete dense block wall with a plaster finish. Where a greater performance is required, consideration should be given to using concrete blockwork with an acoustic panel to one side. Lignacite’s research and development team have evaluated a number of blockwork/ acoustic panel combinations, with surprisingly good results.
Typically an acoustic panel will comprise a 50 or 70mm ‘C’ stud frame, set back about 15mm from the face of the blockwork, with acoustic quilt or a proprietary board, such as Isomass, between or over the studs and finished with high density plasterboard. The advantage of this construction is that it allows blockwork to be used fair face one side, e.g. facing a sports hall, as well as meeting fire and stability requirements. The blockwork and acoustic panel act together to provide raised levels of sound insulation. Tests commissioned by Lignacite Ltd. in a UKAS approved laboratory has shown weighted sound reduction index values, Rw, of up to 65dB can be achieved. Some examples of these high performing constructions are shown.
For further details on the Lignacite range of concrete blocks, please call 01842 810678, email info@lignacite.co.uk or visit Lignacite’s website.
140mm Lignacite SP solid blockwork with acoustic lining to one side Sound insulation = 65 Rw, dB
To date, aircrete from H+H has delivered over 8,000 MMC homes in the UK, making it one of the most widely used materials for the Modern Building agenda. Jenny Smith-Andrews, Head of Marketing at H+H looks at the MMC solutions on offer.
There is no denying that the building industry, and particularly the housebuilding sector, in this country is extremely conservative: slow to adopt new methods and systems. Government clearly understands this. The degree of its intervention, in terms of overt encouragement and financial incentives is marked.
Whether it is any Government’s business to dictate to private sector organisations how they make their product is debatable, but the objective is laudable: to deliver better quality homes, faster, and H+H is well positioned to help its customers reach MMC targets.
Aircrete benefits from being a material widely used across Europe where housebuilding is a very different industry. Hugely popular for its robust, durable and thermally efficient characteristics, aircrete plays its part in the development of modern construction methods delivering high-performance homes.
In the UK, H+H aricrete is fundamental to three Modern Methods of Construction. Our Thin-Joint blockwork provides a fast and accurate means of building exterior walls – meeting the criteria to be rated an MMC category 6.
Put together into a packaged offer combining Thin-Joint exterior walls with ground floors, upper floors and partitions, our Rå Build solution gives the entire weatherproof structure as a single, fast system.
Neither of these offers is new, both have been widely used in Europe for decades. However, in the UK, both have struggled to gain widespread adoption. We certainly see more interest, given the focus on implementing Modern Methods, but for many, Modern means “offsite”. Our Celcon Elements, particularly when used as part of the i-House system, provide the answer that is gaining ground fastest.
Celcon Elements are storey-high panels of aircrete. Craned into place and fixed with Thin-Joint mortar, Elements allow the entire ground floor wall structure to be completed on site in just hours.
Elements, by the way, are not new either, so H+H has a track record of high-performing housing developments across Europe to reassure the UK market of the practicality of this building method.
Elements really come into their own when used as part of a system-build solution, and H+H worked in partnership with Roofspace Solutions to develop i-House™. This combines aircrete walls with prefabricated first floors and roof structures, installed by a dedicated contracting team. Most suitable for large volume standard house designs, the entire building fabric can be completed within five days on site.
In promoting our options for Modern Methods of Construction, H+H is highlighting a common misapprehension around the term MMC. There is no prescription as to the material used or the method of build. To qualify as a Modern Method of Construction, the solution needs to meet the objectives for building faster, more efficiently and to high tolerance. I-House meets the MMC definition at category two.
We know that our industry has a preference for aircrete – a trusted and popular material. 8,000 homes built with Modern Methods based on aircrete is a demonstration that this material is ready for the 21st century building agenda.
The fundamentals of aircrete as a material have not changed since it was introduced into the UK market over sixty years ago. However, it has proved its worth over time and now makes a strong case for inclusion as a Modern Method of Construction (MMC).
It is hardly a secret that since the publication of the dramatic “Modernise or Die” white paper in 2016, government focus has sharpened on the need to support methods of housebuilding that are faster and higher performance.
Much of the debate on the subject focuses on factory-build modular homes, but in fact the definition of MMC is much broader and there is certainly nothing to dictate which materials or method are preferable.
The MCHLG definition makes it clear that it is focused on objectives and is not trying to be prescriptive as to what products or methods are used to achieve them.
Aircrete remains the preferred material for most UK housebuilders. Combining strength with inherent thermal efficiency, aircrete blocks are also easy to use on site and, most importantly, provide the flexibility that housebuilders need when planning their sites. The speed of build can be increased or slowed in reaction to demand or to weather conditions.
Standard aircrete blocks with traditional cementitious mortar are typically used for cavity wall construction. Repeated performance testing demonstrates that such wall constructions are easily able to meet the U-Value requirements of current building regulations and the uplift anticipated when the revised Approved Document L is published.
Where increased airtightness is the objective, the highest performance levels can be achieved with Thin-Joint construction – which has been the preferred choice for various low carbon and Passivhaus certified developments.
The ultra-thin joint which gives the system its name is not only airtight, but also, having a much faster curing time, allows for increased speed of build. With higher tolerances, the method also supports a more accurate build. Both these characteristics contribute to the system being acknowledged as a Modern Method of Construction.
Where a more system-based approach is required – particularly for larger developments of standard house types for affordable or build-to-rent markets – H+H has developed an entirely different solution.
Based on Celcon Elements: story-high panels of aircrete, the I-House system was developed in partnership with Roof Space Limited. The concept was to develop a housebuilding system, based on aircrete, that allowed the entire structure of a house to be built on site within a week.
Celcon Elements provide the walls which are simply craned into place onto pre-prepared foundations. Prefabricated timber first floors and prefabricated roofs complete the structure and the package is finished with exterior insulation. Within a week there is a watertight shell, ready for interior trades to move on site and exterior finishes such as masonry to be applied simultaneously.
Recognised on introduction in 2017 with a Housebuilder award, the I-house system has also been supported with both BPOAS and NHBC warranties and is rapidly gaining ground as an advanced Modern Method of Construction.
For more information on aircrete and on the range of building solutions provided by H+H, visit www.hhcelcon.co.uk.
One was a challenging construction, requiring a 4-metre-high wall, which had to work around contiguous concrete piles and incorporate a footbridge link to the main building. With a limited width available, the piles were clad vertically with stone finish Leromur blocks which transitioned into an inclined planted Betoatlas structure.
