On the north side of the Thames in central London, the three riverside embankments, Chelsea, Victoria and Albert, are the result of extensive civil engineering works that reclaimed marshy land, narrowed the width of the river and provided a large-scale new area of development during the late 19th century. Today almost 150 years later, much of the area is once again being transformed as the result of a scheme designed to replace many of the outdated buildings which have characterised these areas for so long. There will be high specification property construction, promenades and parks; and at Millbank, one of the major residential riverfront developments is Riverwalk.
Riverwalk features two organically shaped buildings of seven and seventeen storeys, connected by a central podium and incorporating 116 high specification one, two, three and four bedroom apartments, plus penthouses. The design focus is on light, space, service and exceptional views across the Thames. Aesthetically the buildings are enhanced by horizontal bands of limestone on the curving facades between the glazing and ceramic panels, with the stonework wrapping around the lower parts of the balconies to create a continuous organic shape.
With such a high specification development, early consideration was given to the avoidance of the thermal bridging at the critical balcony connections. Thermal bridges would result in higher heat transfer through the assembly and colder surface temperatures on the warm side of the assembly.
Some of the consequences of this being higher energy use for heating and cooling, non-compliance with UK Building Regulations, potential building structure corrosion and the risk of mould growth and associated health concerns from respiratory problems. To help minimise any risk of thermal bridging, the structural thermal break module specified throughout the Riverwalk development is the latest generation Schöck Isokorb for concrete-to-concrete applications, the type KXT.
This latest example of Schöck engineering means even better performance, which is critical in meeting the inceasingly stringent EU guidelines and the imminent need for nearly zero-energy building standards. The Schöck Isokorb type KXT pushes the technical boundaries in meeting these demands.
In addition, through close collaboration with its clients, Schöck has also now optimised the load capacity of the Isokorb range. As a result, the load capacities most frequently in demand have been identified and appropriate refinements applied to the product portfolio. The range now provides planners with not only a structurally optimised product solution for the construction of cantilevered components, but cost advantages as well.
Verifiable performance values
The product offers such a high level of insulation, that in Germany the Passivhaus Institute in Darmstadt has awarded the product with the low ‘thermal bridge construction‘ certificate and confirmed its suitability even for Passivhaus construction. The product has also just been awarded the very latest BBA certification. All units meet full compliance with the relevant UK building regulations, which require that the temperature factor used to indicate condensation risk (fRSI) must be greater than or equal to 0.75 for residential buildings. The range also provides Local Authority Building Control Registration and there is compliance too with the UK government Standard Assessment Procedure (SAP 2012) concerning CO2 emissions from buildings and respectively heat losses through non-repeating thermal bridges.
Here, the lambda values of the Schöck Isokorb enable energy loss in various connective situations to be reduced by as much as 84% to 91%.
For a free copy of the Schöck Thermal Bridging Guide and / or the Thermal Bridging Solutions brochure – contact the company on 01865 290 890 or visit www.schoeck.co.uk
Innovative product developments, unrivalled performance certification and an exciting range of software support packages, all combine to strengthen Schöck’s continued position as the number one supplier of verifiable performance thermal break technology.
This year, Schöck pushes the boundaries further with its new generation of Schöck concrete-to-concrete Isokorb, offering unrivalled thermal performance for both standard and Passivhaus construction. Also on display is the Isokorb type AXT – offering a more thermally efficient and more durable alternative to wrapped parapets and minimum savings of 10% on construction costs.
The rest of the Isokorb family, for concrete-to-steel and steel-to-steel connectivity are on display too – all with the reassurance of the new BBA certification, verifying Schöck to the most up-to-date industry requirements. Among the latest software packages there is the new Calculation Software for the Isokorb type KS and the Thermal Bridge Calculator. A brand new customer focussed website is being launched and you can get up-to-date information on the latest BIM developments.
The Schöck team is of course on hand to discuss any of the new developments and to offer ‘live’ consultancy advice on any project specific requirements you may have.
H+H’s Thin- Joint System of aircrete blocks and Celfix Mortar is a key element in the construction of a Passivhaus development of 16 semi-detached houses and 12 sheltered accommodation apartments on the Isle of Wight.
The scheme’s developer, Southern Housing Group, wanted a scheme to meet the low energy criteria defined in the higher levels of the Code for Sustainable Homes without having to rely on renewable technologies. The fabric first, low-energy approach embraced by Passivhaus meet this criterion.
A Passivhaus must be built according to the principles developed by the Passivhaus Institute. These seek to minimise the need for space heating on the basis that minimising heat losses through the building fabric is the most cost-effective and robust way of achieving a low carbon building. The solution relies on maximising the use of fabric insulation, minimising thermal bridges and ensuring buildings are airtight.
External walls of homes on the Cameron Close development are constructed from H+H’s 200mm thick thermally efficient Celcon Plus blocks. These are enhanced externally by an additional 230mm thick layer of phenolic insulation on the houses and 150mm thick layer on the apartments. The insulation is finished externally with a white-colour acrylic render system, a common aesthetic on the Isle of White. The solution gives a U-value of just 0.08W/m2K for the external walls of the houses and 0.11W/m2K for the apartment walls.
In addition to its insulating properties, H+H’s Thin-Joint solution is ideal for Passivhaus construction because the combination of accurately dimensioned Celcon Plus blocks with 2mm thick Celfix mortar joints helps to minimise air leakage through the external walls. David Harris, director or Stoneham Construction is an advocate of the Thin-Joint System: “Passivhaus is all about air tightness so if you can reduce the gap between blocks to 2mm, instead of 10mm, it makes life a lot easier,” he says.
Achieving an airtight build was further helped by the use of H+H’s Retro Fit Joist Hangers to carry the timber joists that support the internal floors of the homes. These enable the wall to be built first with the hangers added after to avoid the need to cut blocks or to penetrate the blockwork walls speeding construction and improving airtightness.
London’s three historic embankments – Chelsea, Victoria and Albert – are currently being transformed as part of a regeneration scheme that will replace many of the outdated buildings which have characterised these areas for so long. The result will see the development of new homes, promenades and parks – and one of these commanding new developments, on the north bank of the Thames, is the stunning Riverwalk, at Millbank, designed by Stanton Williams.
Riverwalk features two organically shaped buildings of 7 and 17 storeys, connected by a central podium and incorporating 116 high specification one, two, three and four bedroom apartments, plus penthouses. The design focus is on light, space and service, as well as exceptional views across the River Thames. Extensive planting on roofs, balconies and terraces, most significantly on the first floor podium terrace, also contribute to a substantial improvement in the green footprint and biodiversity of the site.
Aesthetically the buildings are enhanced further by horizontal bands of limestone on the curving facades between the glazing and ceramic panels, with the stonework wrapping around the lower parts of the balconies to create a continuous organic shape. The balconies vary in depth and this in turn provides the outer façade with a sense of depth, along with natural solar shading.
With such a high specification development it is not surprising to find that enormous consideration was given to the avoidance of the thermal bridging at the critical balcony connections; and the structural thermal break module specified throughout is the latest generation Isokorb type KXT from market leaders Schöck.
The type KXT – for concrete-to-concrete applications – offers such a high level of insulation that the Passivhaus Institute in Darmstadt has awarded the product with the “low thermal bridge construction” certificate and confirmed its suitability even for passivhaus construction.
A major reason for the superior performance of the Isokorb type KXT is the thickness of the insulation body. This is increased from the standard 80mm thick to 120mm, providing an even more efficient solution. The KXT not only improves thermal insulation performance by up to 30% in comparison to to the standard range, it also improves impact sound insulation by around 50% as well. High quality stainless steel bars with improved tensile strength is an integral part of the unit and while the same load-bearing capacity is maintained, there is a smaller rod diameter and therefore a reduction in the thermally conducting cross-section, resulting in a further increase in the heat insulation performance.
A further reason for the superior performance of the Isokorb type KXT is the HTE module, a pressure bearing block made of steel fibre reinforced high-performance concrete with Kronolith, a titanium ore aggregate from Kronos Titan. The unit offers architects and engineers a variety of design options and there is even the capability to construct stepped height balconies, with increased fire protection also taken into account, as the HTE module offers fire-resistance class F 120.
Schöck, is a specialist in the provision of advanced solutions for thermal energy structural insulation and best known for its range of structural thermal break units. It is a range which allows connections to be made between concrete-to-concrete, concrete-to-steel and steel-to-steel and all units meet full compliance with the relevant building regulations, while also providing BBA Certification and LABC Registration. The requirement described in BRE IP1/06 – a document cited in Building Regulations Approved Documents Part L1 and L2 and Section 6 in Scotland – states that the temperature factor used to indicate condensation risk (fRSI) must be greater than, or equal to, 0.75 for residential buildings and this is easily met by incorporating the Isokorb.
In addition, there is also compliance with the Government Standard Assessment Procedure, SAP 2012, concerning CO2 emissions from buildings and respectively heat losses through non-repeating thermal bridges. Here, the lambda values of the Schöck Isokorb enable energy loss in various connective situations to be reduced by as much as 84% to 91%.
Last month the treasury announced the scrapping of the zero carbon building standards. The statement was presented within detailed documents, published as part of George Osborne’s economic productivity drive called, ‘Fixing the Foundations.’
The plans have been received with a wave of disappointment from across the industry. Businesses throughout the UK have been investing heavily, for the best part of a decade, in preparation for these future standards. For example, £6.4million – including £3.2million of public funds – was invested in the AIMC4 project, developing and applying materials to create low carbon homes, now to be told that these standards will no longer be implemented. On the back of this announcement the Green Deal cashback scheme was also axed – chipping further away at the government strategy on dealing with high energy bills through home energy efficiency.
The transition strategy to a low-carbon economy presented our industry with great aspirations for growth. Environmental considerations would help transform how buildings are constructed, what materials are used and the methods employed. I believe that we are now on the cusp of the predicted ‘sea-change’ with UK power generation in need of a significant upgrade. The way forward, in the longer view, seems obvious. Even the power industry is increasingly investing in renewable technology, with start-up organisations developing innovative ways of using local, renewable micro generation to deliver more cost effective energy supply and who passionately believe that they will ultimately change the energy market of the future. For our part government and the construction industry must continue to embrace innovative timber technology and offsite techniques in order to develop better buildings to minimise the environmental impact of high energy demand reducing energy costs for occupants and the energy poverty that is becoming increasingly common.
It would be very easy to view the recent changes to the regulations as a significant blow for the industry and yet I don’t believe it is. The build for rent sector along with the Housing Associations still view energy efficiency and environmental responsibility as core to their organisations. A Landlord doesn’t want the rent spent on paying the energy bills and Housing Associations provide for some very vulnerable families on low incomes who need their home to be economically viable. These realities exist irrespective of government regulation.
By the same token, self builders always adopt much higher standards of energy performance than required by Building regulation and we are experiencing an increased interest in Passivhaus standards. Recent housing forum papers have highlighted just how important this sector is becoming in the mix of solutions to the housing shortage crisis.
The zero carbon homes target is just one of many policies from the government’s platter of promises and undoubtedly the recent reversal of carbon limiting policy is unhelpful. We are only two years into the government 2025 strategy – a strategy which states the requirement for the construction industry to reach a 50% reduction in carbon emissions by this date – this is now becoming further out of our reach. This abrupt decision also comes at a time when the UK should be taking strong action on climate change ahead of the UN conference in December this year. Particularly in light of recent declarations by President Obama’s administration, if we are to maintain credibility within that forum. Whatever the short term solution – there is overwhelming evidence from across the scientific community of the genuine threat that CO2 poses to this country and to our world. This is something that cannot be overlooked.
Without even getting into the bigger scientific issues – the compounded problem of lack of delivery of housing stock during the recession now needs to be reversed and it isn’t the volume housebuilder’s issue to solve, their priorities are set by shareholders. Housing provision is a fundamental responsibility for government just as defence of the realm and energy provision are. Significant increases in home building have always been government inspired and this is still the case today. By announcing this policy change, the government seem to be saying loud and clear that energy efficiency, when it comes to building those new homes, is not going to be a priority and that production of short term ‘cheaper’ homes is taking its place. The fact of the matter is, a U-turn on energy efficiency may reduce initial build costs but not by much compared to the longer term costs to society and national energy demand. Indeed it is exactly those issues that drove the development of the green deal to tackle poor performance in the existing housing stock. The holistic approach of building to high standards now and facilitating the upgrading of existing stock via building regulation and financial instruments is the correct way forward. Our industry has proved time and again that creating sustainable homes is not more time consuming. In fact, it is actually quicker and more efficient to manufacture, deliver and assemble a high-quality, low-carbon timber frame building than build one onsite with lower thermal insulation created from materials which directly contribute to increasing carbon emissions. In this regard timber holds a unique position in the sustainable material agenda and one which is available to rich and poor economies alike. It is a global material supporting a solution for a global problem. It isn’t by chance that the majority of the world’s population live in timber base dwellings.
Kingspan Timber Solutions will continue to keep energy efficiency as a key factor in all of our projects. We recognise the value of low energy homes to the British economy and will continue to invest and innovate in this area. Part of the reasoning to scrap zero carbon homes was that it was an unachievable target that would be costly to the industry. This is something that I strongly disagree with. As a nation we need affordable, well designed and energy efficient homes that address the significant issues of fuel poverty and climate change – particularly within the social housing sector. This combination of requirements plays to the strengths of timber frame and structural insulated panel systems (SIPS), which deliver a sustainable solution. We must not make the short sighted mistake of prioritising ‘cheap’ over ‘cost effective’ when it comes to providing homes. Cost effective, energy efficient homes will ultimately save money for the end user as well as invest money back into the British economy. Energy efficiency doesn’t mean an explosion of high tech, expensive, obsolete eco-bling. The industry has invested heavily in getting building fabric solutions that deliver high performance without the future maintenance costs that renewable solutions entail. This ‘fabric first’ approach, synonymous with offsite construction, focuses on the delivery of an airtight building envelope to achieve sustainable and energy efficient new homes, reducing CO2 emissions, energy consumption and associated costs within wall thicknesses that don’t compromise plot sizes
Kingspan are currently delivering a Self Build Live event which will showcase the first ever Passivhaus show home – demonstrating on a real time basis, the value of creating a home at such a low energy standard. A Passivhaus building requires very little energy for heating or cooling at the same time as providing a high level of comfort to the occupants. Self Build Live will allow visitors to attend and access-all-areas of the build project. This gives attendees the opportunity to view the site at various stages throughout the build and see the new show house come together. (www.selfbuildlive.com for further information)
It is regrettable that zero carbon homes policy has been pushed aside and in the long term this will ultimately cause issues in a range of different areas. The government are going to find it challenging to ‘fix the foundations’ if it keeps digging holes for future generations to fall into.
Kingspan Timber Solutions is a pioneer in sustainable structural timber construction. As the leading innovator in the development and application of structural timber technology, we ensure that process and performance are consistently enhanced. With a collaborative culture, Kingspan Timber Solutions are a dependable partner who, by using a combination of the highest performing, most sustainable materials and components, use our expertise to design, manufacturer, assemble and project manage the construction of cutting-edge timber solutions. Our focus is firmly on delivering value by using the optimum combination of systems to deliver structural hybrid timber solutions, optimised in terms of value and performance.
With a robust, integrated supply-chain, we are dedicated to delivering outcome certainty by working in partnership with clients and their design teams to develop the best solution. With an exemplary track record built throughout our 50 plus years in the business, we are the UK’s leading experts in quality timber-based structural hybrid systems. We have successfully delivered an enviable range of high performance, award winning low carbon projects for a wide range of clients throughout the UK.
To book a CPD session: call: 01767 676400 or email: email@example.com
Reynaers multi-chamber, high insulation aluminium doors and aluminium window system CS 86-HI is now able to accommodate larger glass panes, including triple glazing and pivoting window options.
A special modification to CS 86 now allows the installation of glazing panels from the outside, avoiding the need to transport glass through buildings. The development also allows the use of larger and heavier glazed panels, including triple glazing up to 500kg, offering greater flexibility in terms of both design and installation.
Pivoting openers with hinges fully integrated into the profiles have also been introduced. Depending on the position of the hinges, the pivot window can be supplied with a horizontal axis (max. 200kg), or a vertical axis (max. 160kg). The new system helps create a more flexible building design, allowing glass panes up to a maximum height of 2500mm.
Used extensively on energy efficient and BREEAM rated buildings, Reynaers CS 86-HI aluminium windows and doors incorporate a unique insulation that ensures extreme stability and enhanced water and air tightness. The performance of the system for air and water tightness has subsequently been upgraded to 300 Pa.
Several of the CS 86-HI window and door configurations achieve the Minergie® and Minergie-P® component labels, which corresponds to Passivhaus standards of a Uw value of ≤0.8 W/m2K. When it comes to safety, variants of CS 86 are also compliant with the Secured by Design initiative offering optimum levels of security and performance.
Marketing Manager at Reynaers Rebecca Cope said: “Not only do we try to reduce the company’s energy consumption and its emissions of greenhouse gases with our architectural glazing; we also contribute to limiting the energy consumption of new and existing buildings through the development of energy-efficient windows and doors. The overall insulation value of the system’s HI+ variant makes it one of the most energy efficient systems available.”
Many cities throughout the world are looking for ways in which to cope with population growth, whilst curbing energy consumption and environmental impact. And the unlikely focus of international interest currently is the historic city of Heidelberg, in south-west Germany. Residentially it is very popular and commercially it is very successful, but Heidelberg has an expansion problem. There is barely any property to be had in the city’s picturesque old town, or along the banks of the River Neckar, and if anything does become available, the prices are on a par with those of Munich, in the region of €5,000 or more per square metre.
The spectacular solution is to build a completely new district – the Bahnstadt – on a 286 acre area that was once home to Heidelberg’s now defunct rail freight and marshalling yards. The €2 billion initiative is claimed to be the largest single passivhaus development in the world; and when completed in 2022 it will provide living space for some 5000 residents. There will be a vibrant mixture of culture, education and employment, with around 7000 jobs created, particularly in the life sciences and communication technology sectors. All buildings, not just the 2500 residential properties, will meet advanced passivhaus standards, requiring only 10% of the energy of a conventional building. There are green roofs with only a small number of solar panels, large windows on south facing aspects and small windows to the north. To meet any additional heating needs a mainly wood chip district heating network with “mini-net” distribution will serve the entire district. The energy supply is 100% renewable and Bahnstadt will be the biggest single site in Europe in which the “smart meter” concept is applied throughout, providing each household with an overview of consumption and costs. In terms of energy efficiency, the new district by far exceeds national legal requirements as set out in the current Federal Energy Saving Ordinance, with consumption less than half that of traditionally constructed buildings. Motorised traffic will be mainly subterranean and every building will be equipped with an underground car park and include charging points for electric cars and e-bikes. Cycling is being promoted heavily as the prime means of transport.
Balcony connectivity used to be a problem with passivhaus construction
One of the key criteria for apartment living anywhere in the world these days, not least Bahnstadt, is the aesthetic and practical requirement for the inclusion of balconies. However, with the demands of high insulation levels and the prevention of thermal bridging being critical elements in passivhaus design, the incorporation of balconies has not necessarily been a popular choice with designers. However, the development of the Schöck Isokorb type XT structural thermal break unit has played a major role in resolving that particularly challenging connectivity issue.
Schöck, a specialist in the provision of advanced solutions for thermal energy structural insulation, is best known for its range of structural thermal break units. And its latest generation product for concrete-to-concrete applications – the Isokorb type XT – offers such a high level of insulation that the Passivhaus Institute in Darmstadt has awarded the product with the “low thermal bridge construction” certificate and confirmed its suitability for passivhaus construction.
Thousands of type XT units are being incorporated into the Bahnstadt development and the major reason for its suitability is the thickness of the insulation body, which is increased from the standard 80mm to 120mm. As a result the unit not only improves thermal insulation performance by up to 30% in comparison to to the standard range, it also improves impact sound insulation by around 50% as well. A further reason for the superior performance of the type XT is the HTE module, a pressure bearing block made of steel fibre reinforced high-performance concrete with Kronolith, a titanium ore aggregate from Kronos Titan. The unit offers architects and engineers a variety of design options and there is even the capability to construct stepped height balconies, with increased fire protection also taken into account, as the HTE module offers fire-resistance class F 120. High quality stainless steel bars are also an integral part of the unit. Although there is a smaller rod diameter, the tensile strength is improved and the same load-bearing capacity is therefore maintained. This means a reduction in the thermally conducting cross-section, and an improvement in the heat insulation performance.
Before the Bahnstadt project, the Isokorb type XT had already seen considerable success in Germany, not least for its sound insulation characteristics, as there is now a stated minimum standard requirement for balconies. Previously this only applied to covered balconies, but the XT has the advantage that it conforms to the minimum requirements for impact sound protection – without any additional floating flooring on the balconies or covered balconies.
The Schöck Isokorb range allows connections to be made between concrete-to-concrete, concrete-to-steel and steel-to-steel – and in the UK, all units meet full compliance with the relevant building regulations, while also providing BBA Certification and LABC Registration. There is a requirement described in BRE IP1/06 – a document cited in Building Regulations Approved Documents Part L1 and L2 and Section 6 in Scotland – that the temperature factor used to indicate condensation risk (fRSI) must be greater than, or equal to, 0.75 for residential buildings and this is easily met by incorporating the Isokorb.
In addition, there is also compliance with the Government Standard Assessment Procedure, SAP 2009, concerning CO2 emissions from buildings and respectively heat losses through non-repeating thermal bridges. Here, the lambda values of the Schöck Isokorb enable energy loss in various connective situations to be reduced by as much as 84% to 91%.
For your free copy of the Schöck Specifiers Guide and / or the Technical Guide contact the company on 01865 290 890 or visit www.schoeck.co.uk