Chapter 7
Materials
Jane Anderson1, Michael Beavan2, Francesca Galeazzi2, Miles Keeping3, David Shiers4 and Kristian Steele2
1Thinkstep, Sheffield, S1 2BJ, UK
2Arup Associates, London, W1T 4BQ, UK
3Hillbreak Ltd., Buckinghamshire, HP18 9TH, UK
4School of the Built Environment,, Oxford Brookes University, Oxford, OX3 0BP, UK
In the United Kingdom, the construction materials sector consumes around 400 million tonnes of raw materials every year, meaning it is the country’s largest user of natural resources (UKGBC, 2016).
Choosing building components which, in their manufacture and use, consume fewer resources and are less polluting can, therefore, help to reduce the nation’s carbon footprint and enhance the overall environmental credentials of the building. Construction materials consume natural resources including minerals, fossil fuels for energy production, timber, oil-based products and water have major transport impacts and add to the waste burden as they are replaced and their production processes may release chemicals into the atmosphere including nitrogen oxide and sulphur dioxide.
Although it is generally accepted that the operational impacts of buildings still outweigh the embodied impacts arising from materials production and construction, as the operational performance of property steadily improves, this ratio will come down, thus making the selection of environmentally responsible materials ever more important (CPA, 2012).
- http://www.c-a-b.org.uk/wp-content/uploads/Guide_understanding_the_embodied_impacts_of_construction_products.pdf
- http://www.ukgbc.org/resources/additional/key-statistics-construction-industry-and-carbon-emissions
To assess the environmental impact of a construction material, the embodied CO2 and resources used and the waste and emissions created are measured at each stage of the product’s manufacture, use and disposal. This ‘cradle-to-grave’ analysis is known as life cycle assessment (LCA) and requires the collection and interpretation of often complex and extensive quantitative data collected by environmental consultancies, trade associations, manufacturers and national governments (Figure 7.1).
Figure 7.1 The life-cycle system of a building and its interventions with the physical environment.
Source: The Green Guide to Specification, 2009.
In a simplified example, for the production of clay roof tiles, an LCA would require the measured energy and resources use data for the following stages of the product’s life cycle:
- Winning of the raw materials and their manufacture
- the extraction of the clay from the ground and its transportation to the factory
- the extraction and distribution of natural gas for the kiln
- the mining and transport of fuels for the generation of electricity for use in the factory
- the production and transport of raw materials for the packaging
- the manufacture and transport of packaging materials for the tiles
- the manufacture of the tiles including the energy used and the emissions created
- the transport of the tiles to the building site
- The product in use
- the extraction and production of the materials for fixing the tiles to the roof
- the on-site labour impacts of hanging of the tiles
- the maintenance of the tiles, including cleaning, repairing and replacing
- Removal/demolition and disposal
- the on-site removal of the tiles at the end of their useful life
- the fate of the materials in the waste stream
The Green Guide to Specification is one of the industry’s most widely used sources of information in providing designers, architects and property managers with information on how to make the best environmental choice when selecting materials. Part of both BREEAM and the Code for Sustainable Homes, Green Guide uses LCA data measured against the 13 impact categories of BRE’s Environmental Profiles Methodology to assess the environmental performance of materials, then presents the complex quantitative results in an easy-to-use A*–E rating system where A* is the best choice and E the worst.
The environmental impact categories used and the issues they represent:
| Environmental impact category | Environmental issue measured |
| Climate Change | Global Warming or Greenhouse Gases |
| Water extraction | Mains, surface and groundwater consumption |
| Mineral resource depletion | Metal ores, minerals and aggregates |
| Stratospheric ozone depletion | Gases that destroy the ozone layer |
| Human toxicity | Pollutants that are toxic to humans |
| Ecotoxicity to water | Pollutants that are toxic to the ecosystem |
| Nuclear waste | Spent fuel, high- and intermediate-level radioactive waste |
| Ecotoxicity to land | Pollutants that are toxic to the ecosystem |
| Waste disposal | Material sent to landfill or incineration |
| Fossil Fuel Depletion | Coal, Oil or Gas consumption |
| Eutrophication | Water pollutants that promote algal blooms |
| Photochemical Ozone Creation | Air pollutants that cause respiratory problems |
| Acidification | Gases that cause Acid Rain etc. |
The studies undertaken in developing the Green Guide also revealed which elements within buildings have the potential to have the greatest environmental impact over a notional 60-year life of the average building (including the maintenance and replacement of elements). These elements, therefore, demand particular attention when making a specification choice.
As can be seen in Green Guide, the external walls together with some materials used to provide road and path surfacing in heavily trafficked outside areas, appear to have the greatest environmental impacts. Many external walls comprise high-mass materials, whereas road and path surfacing must often be maintained and replaced at frequent intervals, hence their greater impacts.
Although internal floor finishes such as carpets were not measured in the Green guide of 2009, the pie chart below from the 2002 third edition shows that surprisingly, given their relatively low mass, these had the greatest environmental impact, again due to the large quantities used in the United Kingdom and the number of times they were replaced in the building’s life cycle (Figure 7.2).
Figure 7.2 The environmental contribution of building elements.
Source: From Green Guide, 2002.
A wool/nylon mix carpet with foam backing/underlay was chosen as typical for commercial buildings in 2002. Because carpets are replaced frequently (perhaps as many as 12 times over a 60-year period), the environmental impacts associated with this element could be very significant – around 40% of the total building impacts. However, changing the specification to a carpet with recycled rubber crumb or natural fibre underlay, could reduce by up to two-thirds the overall impact of the floor finishes.
Upper floor structure (forming most of the floor within an office building), had the next largest impact, accounting for around 15% of the total building impacts. Floor surfacing (based on a typical office raised access floor 150 mm high), was the third largest impact. Raised access floors provide modern offices with considerable flexibility, but at 12% of the total, their environmental impact was significant.
Substructure (foundations etc.) had a similarly large impact. The specification of substructure is dependent on the ground conditions and the mass of the structure above. The design of substructure may offer designers possibilities of reducing impact.
External walls made a significant contribution to the impacts of the typical building (around 7% of the total). Walls and windows together accounted for 10% of the total embodied impact.
The impacts of the roof and ground floors were of similar magnitude, both around 5% of the building total. The impacts of both roof and ground floor will increase or decrease depending on the number of storeys in the building, the greatest impact being for single-storey buildings.
As with substructure, the design of ground floors (that is floors in contact with the ground such as basements) is largely governed by the ground conditions and the choice of substructure. Therefore, it was not possible to offer guidance on this.
Of the major design elements, windows had the lowest impact (only 3% of the building total). For a building with higher glazing ratios, the impact of windows will increase as the impact of the external walls reduces.
Superstructure (the structure supporting the floors above ground) has a smaller impact than the other major elements. This conclusion is based on a mix of steel and concrete framed buildings. In fact, the choice of structure makes very little difference to the overall impacts of the building because both account for around 2% of the total.
The smallest impacts (around 1% each for our typical building) are derived from the internal walls (based on a standard open plan office) and the ceiling finishes (based on a combination of suspended ceiling and plastered soffit options).
For the latest information on the impacts of materials, responsible sourcing of materials and BREEAM Chain of Custody verification and standards, see:
- https://www.bre.co.uk/greenguide/podpage.jsp?id=2126 and Green Guide on-line at https://www.bre.co.uk/greenguide/calculator/page.jsp?id=2071
- http://www.breeam.com/BREEAMUK2014SchemeDocument/content/09_material/mat03.htm
- http://www.ukgbc.org/sites/default/files/BREEAM%20Uncovered%20-%20Responsible%20Sourcing%20-%20Summary.pdf
- https://www.bre.co.uk/page.jsp?id=3424
For information on designing for future removal, disposal and replacement, see:
For information on disposal and waste stream issues, see:
- https://www.wbdg.org/resources/cwmgmt.php
- http://www.sustainablebuild.co.uk/reducingmanagingwaste.html
- http://ec.europa.eu/environment/waste/construction_demolition.htm
- http://ec.europa.eu/environment/waste/studies/cdw/Improving%20management%20of%20CDW%20-%20Workshop%20-%20Background%20paper.pdf
For information on initiatives to promote manufacturer product labelling in the EU, see:
- http://ec.europa.eu/growth/tools-databases/newsroom/cf/itemdetail.cfm?item_id=8664
- http://www.ihs.nl/fileadmin/ASSETS/ihs/Marketing/prospective_students_pages/ECO_and_MFUI/GREEN_LABELS_Final_report_edited1.pdf
- http://www.ecolabelindex.com/ecolabels/?st=region=europe
Hazardous and Deleterious Materials
If found in existing buildings, materials which are deemed hazardous (e.g. Asbestos) or deleterious (degrading) must be carefully managed and/or disposed of by taking expert advice and following the appropriate technical guidance notes for example:
- https://www.designingbuildings.co.uk/wiki/Deleterious_materials_in_construction
- https://www.rics.org/uk/shop/Investigating-Hazardous-Deleterious-Building-9898.aspx
- http://www.hse.gov.uk/comah/sragtech/techmeassegregat.htm
- http://www.hse.gov.uk/waste/hazardouswaste.htm
The use of construction materials which can be harmful to human health such as some chemical treatments, adhesives, solvents and so on are governed by the COSHH Regulations.
Materials Case Example: Druk White Lotus School, Ladakh: the humility of the learning process
The idea of having a modern school which lays equal emphasis on the importance of preserving the valuable aspects of a traditional culture is very encouraging.
I have always believed in giving equal importance to both modern scientific knowledge and traditional Buddhist culture.
His Holiness the Dalai Lama
Located at an altitude of 3,500 m and accessible only for 6 months of the year, Leh Valley in Ladakh, northern India, is bordered by Tibet and Pakistan. Arup have been working with a trust charity since 1997 to design and create a school for local children and a place of cultural learning and communication for the whole region.
The Lea Valley, Ladakh, India.
See:
- http://www.arupassociates.com/en/case-studies/druk-white-lotus-school/
- http://www.arup.com/projects/druk_white_lotus_school/druk_white_lotus_school_film
- http://www.arupassociates.com/en/exploration/local-stone-druk-white-lotus-school/
- http://www.designshare.com/index.php/case-studies/druk-white-lotus-school/
- http://www.arupassociates.com/en/projects/
Conceived as a model for sustainable development in the Ladakh region, the school is designed to cater for 750 pupils from nursery age to 18 years old.
Perched in the Indian Himalayas, the school must also withstand extreme temperatures and earthquakes. Arup’s design for the school combines sustainable local materials and traditional construction techniques with leading-edge environmental design.
A team of architects and engineers from Arup and Arup Associates is responsible for the master plan, concept and detailed designs of each phase of construction. The first phase, the nursery and infant courtyard, opened in September 2001, to be followed by the junior school in 2005. The final phase, the senior secondary school, was completed in 2013.
The project is the brainchild of His Holiness Gyalwang Drukpa and is executed by Drukpa Trust, a UK-registered charity. To support the school, each year, Arup gives an engineer or architect from the design team unpaid leave to work on site. They act as ambassadors for the Trust and help the local construction team.
The school's buildings are flexible and provide an excellent learning environment. All this is achieved using local sustainable materials and building techniques.
The location also has many advantages. At an altitude of 3500 m, the school is ideally placed to use solar energy.
In October 2008, the first phase of the Druk White Lotus School 42 kWp photovoltaic system was completed, providing reliable power to the whole site. It uses an initial installation of 9 kWp of PV panels, which also act as external shading devices for three of the school buildings. The PV installation was 60% funded by Arup Associates, who used this project to offset their carbon footprint for 2007. Previously, electricity was available only intermittently from the local grid or by operating the school’s diesel generator. The system includes batteries to provide electricity in hours of darkness, which can also be charged from local mains electricity or the site generator.
The school provides a quality teaching environment, previously unavailable in Ladakh, and will respond to the specific cultural needs of the people. The project has received a number of World Architecture Awards: Best Green Building, Best Education Building and Best Asian Building in 2002.
See video at: http://www.arup.com/projects/druk_white_lotus_school/facts#!lb:/projects/druk_white_lotus_school/druk_white_lotus_school_film
The school is designed around the circular ‘mandala’ form – an ancient Indian symbol of wholeness and ultimate symbol for the organisation.
Master plan model.
Construction photograph and model of the Pema Karpo library.
Source: Image courtesy of Arup Associates.
Aftermath of a mudslide in 2010.
The finished timber structure.
The completed Pema Karpo Library.
Many of the challenges of the project were as a result of its remote location and extreme environment. It would have proved very difficult to source many of the materials required to build the school. Even though the design would utilise local materials as far as possible, some would simply not be available for a building of this type and size. For example, steel and large timber sections had to be imported from Kashmir and double-glazing units needed to be made by importing single-glazing and assembling the units on-site so as reduce travel distances for the supply of materials.
The energy supply to the site was by means of electricity and was available only intermittently from the local grid or by operating the school’s diesel generator. With such an erratic source of energy, even the use of power tools would be affected. This would have to factored into the design of the building to ensure that assembly of the components would be possible under such conditions.
A thorough understanding of traditional building morphologies, local materials and assembly techniques required extensive study prior to undertaking the design of the proposed school . Arup worked closely with the local craftsmen to better understand how materials were used and detailed, as many of the local craftsmen were unused to referring to architectural drawings.
The extreme nature of the mountain desert location meant that the design team would have to face the challenges of seasonal day-to-night temperature ranges of between +35 to −30 °C. Torrential rain and mudslides were common and the building would have to comply with Indian seismic codes to prevent damage from earthquakes.
In order to fulfil its primary function, the school would have to provide a safe and secure environment, conducive to learning, with comfort being paramount to the happiness and well-being of the children and the teachers.
One of the first phases of the design process involved studying local, traditional building types, including the monasteries in the region. The layout of the buildings was found to often utilise the traditional nine-square grid of the mandala surrounded by a series of concentric circles.
Traditional techniques of warming and cooling, utilising thermal mass and cross-ventilation were researched, then incorporated, but supplemented with a number of appropriate modern technologies to create excellent day-lit, naturally ventilated spaces, passively heated by the sun. It was also a requirement that the design required minimal maintenance and running costs, while providing accommodation to modern standards.
The school buildings consist of a series of classrooms and staff offices grouped in two parallel buildings, planned around an open courtyard, which provides play areas and additional secure outdoor teaching spaces.
The buildings, appositely separated to avoid overshadowing, take maximum advantage of the unique solar potential of the high altitude location by using glazed, south-facing facades to gather the sun’s energy and high thermal inertia walls to store the gained heat.
On winter mornings the daytime teaching areas are quickly heated up by means of combining optimal 30° south-east orientation with fully glazed solar facades.
In the summer, operable windows and roof lights allow cross-ventilation for cooling and fresh air.
All classrooms are entered from the courtyard via a lobby, which provides a thermal buffer. Each classroom has a quiet warm corner, with a small stove on a concrete floor that is used only on days of extreme cold weather. Timber floors elsewhere and white-painted mud rendered walls are provided for maximum teaching flexibility in clear, uncluttered spaces.
During the construction planning phase, the site manager was of particular importance in liaising with the craftsmen who built the school and Arup used mock-ups to develop assembly details so that a two-way dialogue would be possible.
Whilst the location of the project presented many challenges, it was found also to offer some opportunities which the designers turned to their advantage. At an altitude of 3500 m, the school is ideally placed to use solar energy. The system chosen includes batteries to provide electricity in hours of darkness, which can be charged also from local mains electricity or the site generator.
Water is a limited resource and so, solar power was used to pump ground water to a tank on the northern boundary of the site. The water distribution network then supplied the school, reusing some water for irrigation of planted areas to supplement the low rainfall of the area.
Solid granite blocks used for the outer wall came from stone found on or adjacent to the site. Inner walls were made from local mud brick, forming cavity walls for significantly improved insulation and high durability. The roof is of a traditional Ladakh mud and timber construction, including poplar and willow from local monastery plantation.
By supporting the heavy roof on a structure that is independent of the walls, Arup's design team made sure that the school was built to the Indian seismic code.
Durability, flexibility and earthquake soundness are central aspects that govern structural design in this highly seismic zone. Ladakh is classified in seismic zone IV, the second highest category of the Indian Building Code. Although there have been no major earthquakes in the area in recent times, Ladakh has frequent tremors. The disasters caused by the Gujarat (2001) and the Pakistan (2005) earthquakes showed the lack of well-engineered earthquake-resistant buildings in India and Pakistan and the devastation that can result, so that a strong seismic strategy was developed for the Druk White Lotus School. The building structures use timber frames to resist the seismic loads and ensure life safety in the event of an earthquake. Traditional Ladakhi buildings are not engineered for seismic design, but with the application of some simple structural principles and details, a huge improvement in earthquake safety can be achieved. One of the aims of the project is to act as an educational tool in the appropriate application of seismic design to traditional construction techniques. Thus, all structural solutions such as steel plates for the beam-column connection and cross bracing cables are exposed, revealing the simple yet effective solutions adopted.
All buildings have cavity walls on three sides. Granite blocks set in mud mortar are used for the outer leaf, while traditional mud-brick masonry is used for the inner leaf. This gives increased thermal performance and durability compared to the locally rendered mud-brick walls. The Ladakhi-style heavy mud and straw roof is used and is supported by a timber structure that is independent of the walls. Steel connections and cross bracings provide earthquake stability. Despite the complexity of the structural analysis, the design has been translated into simple solutions that have been easily understood by the local craftsmen, and construction made within the constraints given by local materials and techniques (http://www.arupassociates.com/en/news/druk-white-lotus-school-mud-slide-defenses/).
Bibliography
- Anderson, A. and Shiers, D. (2002) The Green Guide to Specification , Third edn, Wiley-Blackwell.
- Anderson, A. , Shiers, D. and Steele, K. (2009) The Green Guide to Specification , Fouth edn, Wiley-Blackwell. http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1405119616.html (accessed 14 June 2017).
- Anderson, J. , Thornback, J. , Construction Products Association (2012) pp. 53, Report in pdf form available at http://www.c-a-b.org.uk/wp-content/uploads/Guide_understanding_the_embodied_impacts_of_construction_products.pdf (accessed 14 June 2017).
- Carter, B. (ed.) (2006) Building Culture: Druk White Lotus School: A Sustainable Model for Education + Design , School of Architecture and Planning, University of Buffalo, State University of New York in Buffalo, New York.
- http://www.dwls.org/ (accessed 14 June 2017).
- http://www.dwls.org/sustainability.html (accessed 14 June 2017).
- Intelligent Buildings International (2009) piece: http://www.academia.edu/2506608/Druk_White_Lotus_School_Ladakh_India (accessed 14 June 2017).
- The Construction Products Association (2012), A Guide to Understanding the Embodied Impacts of Construction Products. http://www.c-a-b.org.uk/wp-content/uploads/Guide_understanding_the_embodied_impacts_of_construction_products.pdf (accessed 14 June 2017).
- UK Green Building Council (UKGBC) (2016) Key Statistics and Carbon Emissions data sheet, available at: http://www.ukgbc.org/resources/additional/key-statistics-construction-industry-and-carbon-emissions (accessed 14 June 2017).
Conclusions
This book does not claim to provide the reader with the definitive guide to achieving integrated, sustainable development; nor can it explain how to design and build with zero negative environmental impacts. However, a number of common principles run through the projects presented here which, if applied, may at least be helpful in delivering a lower carbon-built environment where the potential negative effects of schemes can be minimised.
After studying the projects described in this book, the editors have reached three important conclusions about designing excellent buildings which are also sustainable:
- Although identifying and analysing the objectives and constraints of a project in detail can involve much time-consuming research and consultation, these efforts ensure that integrated, achievable solutions are delivered which address the functional, economic, aesthetic, social and environmental needs of users and the wider community.
- All relevant design decisions should be considered together by a collaborative team consisting of like-minded specialists as ‘only the intimate integration…of disciplines will produce the desired result.’
- Designers and engineers should see themselves first and foremost as facilitators, helping to achieve the aspirations of stakeholders and the society. It is perhaps in the humility of the enabler that the spirit of Sir Ove Arup most clearly endures.