Issue 11 ~ 9th April 2010

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Contents

Overview
- Low carbon construction materials

Networking Opportunities
- Low Carbon Best Practice Exchange

Q&A
- Nigel Anderson, BSRIA

Case Studies
- The Hackbridge project
- Energy savings in buildings

 

Welcome to the Issue 11 of The Low Energy Buildings Bulletin.

In this issue we continue our exploration of low carbon building materials and methods of low carbon construction. Professor Peter Walker gives a detailed explanation of some alternative construction materials and their considerable benefits in this month’s overview article.

Our Q&A is with the Head of Design and Innovation at the Building Services Research and Information Association, and case studies this issue examine the innovative Hackbridge project and a detailed investigation into how air filters can lower the energy consumption of a building.

We are also expanding our coverage of the low energy building sector by presenting two webinars. For those of you not familiar with the concept, webinars are live, online seminars in which the presenter and attendees are connected with each other over the internet. This means that you can attend an informative presentation from the comfort of your own desk – all you need is a computer, thus eliminating unnecessary travel-based carbon emissions and saving time.

The first webinar examines some of the steps that need to be taken to drive the move towards zero carbon housing. It is hosted by Gareth Davies, Director of NewEra Controls, who specialise in energy and environmental control systems, and Hasim Altan, a lecturer at the University of Sheffield with expertise on sustainable architecture and sustainable environmental design. For more information on the Zero Carbon Housing webinar, taking place on 15 April at 4pm, and to book a place, please click here.

The second webinar is hosted by Professor Peter Walker, who will be expanding on some of the points covered in his overview article for this issue, and exploring how alternative materials and construction methods can help achieve low and zero carbon buildings. An expert in the field, Professor Walker is also Director of the BRE Centre for Innovative Construction Materials, and has years of experience on the subject. His webinar is on 4th May at 11am. For more information on the ‘Low Carbon Construction Materials’ webinar and to book a place, please click here.

Keep up-to-date with the Low Energy Building Bulletin and other sustainable construction and design news on our Twitter profile: http://twitter.com/LowEnergyBuild

If you have any feedback, press releases or suggestions for articles, case studies or Q&A figures, please don’t hesitate to get in contact: tristan@carbon-innovation.com

Tristan Parker
Editor

Low carbon construction materials

By Professor Pete Walker, Director of BRE Centre for Innovative Construction Materials – Department of Architecture and Civil Engineering, University of Bath

Plants (including trees – timber – reed, straw, bamboo and hemp) have provided the raw materials for building throughout much of human history. Many vernacular techniques around the world continue to relay on natural and locally sourced materials. Although the industrial revolution displaced many natural technologies, concerns over the environmental impacts of building and infrastructure have stimulated a renewal of interest in plant crop-based materials such as hemp and straw and other traditional materials such as unfired clay and lime.

Using plant-based materials reduces the climate change impact of building development, achieved through use of a sustainably grown renewable resource and the atmospheric CO2 used up by the plants during their growth. Plant-based materials also offer other benefits, including very high levels of thermal insulation, passive hygrothermal regulation of building spaces, providing healthier living spaces. Recently, two techniques have captured the attention of the wider construction industry: hemp-lime and prefabricated straw bale construction.

Hemp-lime is a lightweight composite building material that combines renewable plant based aggregates (hemp shiv) with a lime-based binder. It is a non-structural material used for walls, roof and under-floor insulation. It is used together with a structural frame, typically of timber construction. The lime binds the hemp together and protects the shiv from biological decay as well as providing fire resistance.

The shiv used in hemp-lime is sourced from the stem of the hemp plant (cannabis sativa). Hemp is an industrial bast fibre crop grown as a break crop in the UK between April and September. After harvesting, the higher value outer fibres are stripped away from the inner stem. The shiv is made by cutting the inner stems into chips between 4 and 25mm in size. Around 60% by mass of the hemp plant is comprised of shiv, with typical total plant yields in the UK of around 8–12 tonnes per hectare.

Hemp shiv is very hydrophilic, with a capacity to absorb up to 450% of its own weight in water. Rapid de-watering of the binder by the hemp during initial mixing can significantly impair the hydraulic set. This has led to the development of specialist formulated lime-based binders for hemp construction. These formulated binders are blends of hydrated lime, cement, and pozzolanic additions (such as ground granulated blast furnace slag). The binder initially sets hydraulically and then hardens further through carbonation.

Hemp-lime materials are either cast (lightly tamped) inside formwork or spray applied in-situ. Mix proportions of hemp shiv, lime binder and water vary depending on use (wall, floor or roof mixes) and the method of application (casting or spraying). Cast walls are lightly tamped horizontally inside formwork. Sprayed hemp-lime is applied in vertical layers against one layer of permanent formwork. Following initial set and drying the hemp-lime is finished off with a breathable plaster or render, generally lime-based.

As well as hemp-lime, hemp fibres are also used in construction to produce insulation quilted batts. Products often include polyester fibres, to improve ‘loft’ and stability. Hemp-fibre insulation quilt is suitable for a wide variety of building applications, including external walls. Like many other natural materials it is hygroscopic, which enhances its heat storage capacity.

Straw bale construction has been used, to varying extents, for over 100 years. Bales may be used to form modest loadbearing walls or as in-fill material in framed construction. Bales are a cheap and abundant renewable crop-based resource. But despite success in a number of largely self-build projects, there has been little wider uptake of straw bale. Barriers to wider adoption include uncertainty over technical performance characteristics (especially durability and fire resistance of straw) and high manufacture costs of on-site construction, subject to delays due to inclement weather. Although modular in size (nominally 450mm wide x 350mm high x 1000mm long), dimensions and compaction density can also vary significantly; bale lengths can easily vary by ±100mm. This causes problems for construction and robust detailing. Loadbearing construction relies on a period of settlement prior to the application of the render, prolonging the period of construction.

Development of off-site prefabricated straw bale panelised construction seeks to overcome these barriers. One approach, ModCell™, uses timber framed panels in-filled with straw bales. Panels are typically 490mm thick, with varying heights and widths to suit. The thermal transmittance of these panels is 0.19 W/m²K. In construction the straw bales are compressed vertically to improve their structural robustness and dimensional regularity in preparation to receive plasters, renders or timber based fascias. On completion of straw in-fill and compaction, the internal and external faces of the panels are covered in a formulated lime-based render. It is important that the bales remain for prolonged periods at moisture content levels below which biological decay are likely to occur (around 25%). The facings must therefore protect the bales from direct weathering but also allow water vapour to escape as part of a breathing wall system.

Plant-based materials, such as hemp and straw, offer exciting new opportunities, broadening the range of materials available to the designer, builder and client. Although their use still remains a small fraction of mainstream construction, interest in these technologies has never been greater. Initiatives in response to climate change, including the Code for Sustainable Homes, has provided the framework and stimulus for this increased interest and encouraged growth in the use of lower carbon building materials. To enable wider market development, further research and innovation are required to overcome technical and commercial barriers, supported by both government and private investment.

Earthen architecture has a very long vernacular tradition throughout civilisation. In pre-industrialised society earth was often the building material of necessity rather than choice. The absence of affordable alternatives, combined with its widespread availability and low cost has seen it used successfully around the world. Earthen buildings are found throughout Europe, with an estimated 500,000 occupied in the UK. Other western European countries, such as Germany, France, Italy, Spain and Portugal, have similar – or even higher – proportions of historical earth buildings.

Building with earth comprises using natural sub-soils – often together with other materials – to build walls, roofs and floors of buildings and other structures. A wide variety of techniques have developed through vernacular use, falling broadly between wet mud methods, such as adobe and cob, and dry compacted methods, including rammed earth and compressed earth blocks. Methods reflect the variations in qualities of raw materials and regional constraints, including access to other resources and climate.

Traditionally, walls are generally solid and thick, with comparatively few openings. This has provided buildings with high thermal mass that provide comfortable living spaces in a range of climates. Thick walls reflect low strength of the material and its susceptibility to loss of strength in contact with water. The use of natural soils, with very little processing, offers a building material with very low environmental impact. This has been a primary driver in the renaissance of earth as a modern building material in the UK. Traditional techniques, such as rammed earth, have been recently used to build highly desirable, and expensive, modern buildings. However, it is unlikely that vernacular techniques, such as cob and rammed earth, will have a significant impact on future building practice in developed, high labour cost, economies. Modern developments, such as extruded bricks and panels, plasters and mortars and future innovations will, however, continue to provide new opportunities and markets for unfired clay buildings.


For more information on the BRE Centre for Innovative Construction Materials, visit: http://www.bath.ac.uk/bre/

10 June 2010, Olympia Conference Centre, London

With its uniquely interactive format, the Exchange allows you to benefit from the collective experience of over four hundred members of the network. An extensive programme of roundtable discussion groups, together with a unique pre-arranged meetings service, enables you to link-up with counterparts from similar organisations, many of which will have overcome some of the challenges that you now face.

Many network members have already volunteered to share their experience by hosting a roundtable discussion group at the Exchange. These include representatives from: Aviva, BAT, BBC, BT, Cadbury, Cambridgeshire County Council, Commercial Group, Eastleigh Borough Council, Fujitsu, Gateshead Council, Greenwich Council, Hallmark Cards, J Sainsbury, London Borough of Sutton, Manchester City FC, Microsoft, Mills & Reeve, Nabarro, Newcastle University, nPower, Northern Rail, Oxfordshire County Council, Premier Foods, RBS, Reckitt Benckiser, Renault, Royal & Sun Alliance, Royal Mail, Scottish Power, Severn Trent Water, Shire Pharmaceuticals, Suffolk County Council, Tamar Foods, Thanet District Council, Thomas Cook, Uniq Prepared Foods, Welsh Assembly Government, Whitbread and WHSmith Retail.

Previous participants at these Best Practice Exchange events will know how useful they are for planning carbon reduction initiatives. All members, including those who are yet to give them a try, are encouraged to register for an early-bird place ... thereby saving £100 from the normal participation fee.


Founded in 1955, BSRIA (the Building Services Research and Information Association) is a not-for-profit member association, created to provide a range of services and best practice industry guidance to help companies and organisations improve the design, construction and operation of their buildings, including effective use of energy. This is done through a variety of methods, including product testing and market research, validation of computer modelling, environmental assessments and facilities management strategy.

Nigel Anderson is Head of Design and FM Innovation at BSRIA.

Please give me some information about BSRIA and its aims:

BSRIA is a consultancy, test and research company helping construction and building services companies to become more efficient and effective.

BSRIA’s services are fully independent. We do not distribute profits but invest in our ongoing research programme. This independence means that we provide an objective approach and the most appropriate solution, as well as authoritative reports that are widely recognised and accepted.

We serve the whole built environment chain from client to consultant, contractor and facilities manager. BSRIA has: 55 years of research and consultancy experience where we have seen and solved many problems for thousands of clients. We also have a turnover of £10 million and 160 people with a depth of expertise across all industry sectors.

What kinds of work does BSRIA carry out in relation to ‘low carbon engineering’ / energy-efficiency / sustainability in buildings, and can you give me a few examples of BSRIA’s work/consultancy in these areas?

BSRIA offers low carbon engineering support through all phases of a building project; inception and briefing, design, construction, commissioning and handover, operation and maintenance, refurbishment and demolition.

Low carbon strategies enable our clients to:

Where to start?
There are many options, some still unproven, and alternatives come with a wide range of price tags. Decision makers must find practical solutions that deliver real, economically viable benefits. The solution must be right for a particular building and its purpose; it is expensive to install inefficient low energy or renewable technologies, simply to be environmentally friendly. Buildings still need to be comfortable for occupants and
have quick pay back on low carbon investments.
At BSRIA we recognised some years ago that there is a very strong linkage between understanding how buildings work in practice - the facilities management role - and the input that a designer has to an innovative building. We brought together two of our operational groups under the one ‘Design & FM Innovation’ banner in order to shorten our own loop between learned site experience and theoretical design. Design and FM Innovation is the BSRIA Team which I manage.
Low Carbon Engineering goes further than this. It brings together all of the very varied services that BSRIA supplies to different market segments and ensures that the knowledge embedded in the people who carry them out is made available to industry. The list is long and covers every section of the business, for example:

In your view, what should be the immediate main priorities for improving the sustainability and energy efficiency of the built environment?

Retrofit solutions to our existing stock of buildings have to be high on the list of priorities. For example, housing in the UK accounts for 27% of carbon emissions. More than 70% of the houses we will be living in 2050 have already been built. To meet the UK’s target of an 80% reduction in carbon emissions by 2050, we must dramatically improve the performance of our existing housing stock. Similar arguments apply to commercial buildings, as around 60% of all the buildings that will be standing in 2050 have already been built.

An example of BSRIA’s direct involvement in this area is the current project, Energy Monitoring and Data Recording for Solid Wall Insulation and Retrofit Field Trials.

The Energy Saving Trust has appointed BSRIA for this major new contract to carry out energy monitoring and data recording for solid wall insulation and retrofit field trials in up to 200 existing homes across the UK. The contract is valued at approximately £700,000 and will run to April 2013.

The contract covers two similar projects, the first being the energy monitoring of Energy Saving Trust’s field trials of solid wall insulation and the second as part of the Technology Strategy Board's 'Retrofit for the Future' competition.

The project will work with the insulation industry to support the installation of new and existing forms of solid wall insulation, with in-situ monitoring of performance. Recently, several new insulation products have entered the market. They are still developing and their in-situ performance has yet to be established, but they do offer potential for the millions of un-insulated solid walled homes in England. The purported energy savings vary widely and their acceptability to householders has yet to be determined. The aims of the project are therefore to establish the in-situ performance of a wide variety of solid wall insulation systems, with a focus on reduced energy consumption and carbon savings.

Should there be stronger legislation to improve the environmental performance of buildings?

Yes. Energy is used in buildings for space heating, cooling, ventilation, lighting, hot water and for electrical appliances. Combined, these applications result in buildings being responsible for nearly half of all UK CO2 emissions. Building technologies therefore form a key part of any strategy to reduce carbon, so improving their environmental performance is crucial. Building Regulations only address new buildings and major works - there is no intervention for the vast majority of existing buildings. These need to be addressed through a mixture of education, legislation, incentives, and direct government action to regenerate the building stock.

How should the balance between carbon-neutral new-build properties and energy-efficient retrofitting be addressed?

Through education, legislation, incentives and direct government action:

How important will renewable energy technologies be in creating a sustainable and energy efficient built environment?

It's absolutely vital that the much more of our electricity production comes from renewables, including wind, wave, tidal and solar power, however the way to address this is through the power industry, not just through the building industry. Wherever feasible, buildings should employ heat-raising technologies such as heat pumps, biomass and CHP. However it should be recognised that these technologies are not feasible for every building.

The industry is beginning to demonstrate that, whilst renewable energy technologies may well be specified for new-build projects, usually to meet minimum planning and building regulation requirements, the full energy benefit is not always realised in practice, due to post handover operational difficulties with these new and often complex technologies. BSRIA is making big strides in addressing the issues of matching user and design expectations with post occupancy reality through the Soft Landings framework.

Soft Landings radically changes the way buildings are designed and handed over, encouraging a culture of professional aftercare, system fine-tuning and building performance evaluation techniques at the start and end of a building project.

Soft Landings not only describes a way of passing a building smoothly from the build phase to the occupation phase, but also a mechanism for ensuring that the operational needs of the building are fully considered and appreciated at the design stage. In essence, Soft Landings ensure a graduated, gentle touchdown for a new building, not a painful belly-flop.

In your experience, what are some of the main barriers in place for organisations trying to improve the energy efficiency/sustainability of their buildings?

In all developed countries, resources such as land, water and fossil fuels are way under priced. Until the prices of these resources begin to reflect the need to conserve them for future generations, organisations will continue to use them up as if they were limitless.

Whilst some organisations do recognise available financial benefits through improving the energy efficiency and sustainability of their buildings, we still see Corporate Social Responsibility as the main driver in many companies, particularly the global corporates. This suggests the cost of energy is still not hurting enough, to force real change.

Are government targets for reducing carbon emissions – such as an 80% reduction by 2050 and all new-build homes to be zero carbon by 2016 – achievable?

Of course they are achievable, but at the current rate of change, we are not going to get there in time. Whether our government, and future ones, make this a reality is up to them. In the case of the 80% reduction in CO2 emissions by 2050, to neglect this would represent the greatest failure of leadership in our generation.

What have been some of BSRIA’s proudest achievements?

BSRIA is very proud of its impressive record of achievement in the UK Government Honours systems. A total of five members of BSRIA staff have received awards which, for such a small organisation, speaks very highly of the quality of our people.

The latest is Anne King, Marketing and Membership Director of BSRIA, who has been awarded an MBE in the 2010 New Year's Honours in recognition of her services to the construction industry.

Anne has worked at BSRIA for 30 years, bringing her economist's skills to the market intelligence group. After fifteen years of market research on a consultancy basis, she moved on to the marketing of BSRIA's own activities and is now Marketing and Membership Director. She has also been a leading member of the best practice programmes and is currently on the delivery team for the Knowledge Transfer Network for the Modern Built Environment working in issues around process improvement both of the construction process and the management and operation of buildings.

 

For more information on BSRIA, visit: http://www.bsria.co.uk/

The Hackbridge Project

Background

Hackbridge is a suburb within the London Borough of Sutton and is home to approximately 8,000 people. The area is largely residential and housing includes 18th century listed cottages, late 19th century terraced houses, inter-war semi-detached homes and BedZED, the internationally recognised development of 100 homes built to sustainable design principles in 2000.

In 2005, Sutton Council stated its commitment to moving towards ‘One Planet Living’; a concept based around ten sustainability principles and developed by BioRegional. This is set out in the Core Planning Strategy BP61 as a,

“... key long-term target …to reduce the ecological footprint of residents to a more sustainable level of 3 global hectares per person by 2020 from the current ‘3-planet’ baseline of 5.4 global hectares.”

Read the full story on the Forum


Energy savings in buildings – Camfill Farr

First there was the low-energy light bulb. Now, the low-energy air filter is becoming the ‘must-have’ for facilities managers looking to make quick energy savings and cut carbon emissions. Due to improved technology – meaning potential cost savings of 30% a year plus a changing regulatory framework – many companies are already making the switch to low energy air filters and in the process, saving themselves millions of pounds in facilities running costs.

This translates into a sizeable cost saving given that energy represents 70% of an air filter’s lifecycle cost, and that air filters account for 30% of the total operating cost of a heating, ventilating and air conditioning (HVAC) unit.

Read the full story on the Forum

If you have selected to read any of the above case studies you will be aware that they are posted on our forum. Our forum was created to enable discussion, and case studies are posted in order to facilitate dialogue surrounding these topics.

In addition to this the forum allows members to begin their own discussions. In the 'Low Energy Buildings Innovation Forum' area you are able to post your own threads or respond to those that have been begun by others. This facility provides a fantastic opportunity for knowledge transfer and a great networking opportunity to find the right people to work with your organisation.

If you would like to make full use of the forum please register yourself with a username at http://www.carbon-innovation.com/discussion/





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