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Sustainabilty
Defined as 'development which meets the needs of the present without compromising the ability of future generations to meet their own needs' (Brundtland, 1987), the objectives of sustainability include protection of the environment, the prudent use of natural resources and the maintenance of stable economic growth, employment and leisure. Sustainability includes 'recycling' existing buildings by adaption and conversion (Sustainable Development 1994), making historic building conservation a key to sustainability.
Despite this, surprisingly, there is little data available on the savings (in costs and carbon emissions) which can be made by reusing existing buildings and sites. The ecolabelling of materials and ecoauditing of buildings are still not universally applicable, and life cycle assessment of materials and the definition of embodied energy still lack agreed methodologies. In Britain, we still do not have an equivalent to the 'Blue Angel' system piloted in Germany as long ago as 1978, and environmental impact assessments, BREEAM ratings and EcoHomes standards such as the Code for Sustainable Homes, still do not recognise the advantages of reusing existing buildings. English Heritage has only just (reported in Building Design 25 January 2008) initiated research into the best ways to mitigate the effects of climate change and improve energy efficiency in the 20% of British homes that were built before 1919. We may have advanced beyond the 1987 DES study which encouraged installing industrial style suspended ceilings to save energy, ruining the interiors of countless historic churches and halls, but regulations and standards still fail to recognise the thermal performance of many traditional wall constructions; organic insulation materials (wool, cork, flax, jute, cellulose or wood fibre) still tend to be seen as innovative and British Standards discourage the use of reclaimed materials. 'New' technologies such as composting and low-flushing toilets, straw bale and earth building and even the use of timber shingles can lead to conflicts with authorities, while improvement grants and mortgages can still require unnecessary damp proof courses and timber treatment. Unfortunately, despite the publicity given to 'zero carbon' housing, the reality on the ground is that inflexible legislation and professional liability still militate against sustainability, and overlook the many advantages of reusing old buildings.
Meanwhile in the UK 6 tonnes of building materials are still used per person each year, accounting for 10% of all energy consumption and producing 70 million tonnes of waste; over a third of which goes to landfill, while only 4% is recycled (Sustainable Construction). The government call for 'eco-towns' to provide 2 million new affordable carbon-neutral homes by 2016 completely ignores the resources consumed in constructing them and in demolishing existing buildings to clear 'brown field' sites for them (Smales). Of the 3.5 million bricks produced annually in Britain, 2.5 million are destroyed due to the use of cement mortar (Rodwell, 2007). Although the amount spent on repairing and maintaining existing buildings has been rising steadily for the past 30 years, of the £58 billion spent each year on construction, 50% is still spent on new buildings. Meanwhile, many modern building components, such as PVCu windows, produce damaging pollution both in manufacture and disposal, and are incapable of adaptation or economic repair; being multiple material composites, they are also extremely difficult to recycle. Aluminium similarly has been calculated to have as much as 126 times the 'embodied' energy of timber.
Historic technologies sustainable
By contrast with modern factory processed, energy intensive, composite building materials, sometimes transported hundreds or thousands of miles, to construct highly serviced 'sick' buildings, the construction of most of our historic buildings was broadly sustainable.
Materials were mainly locally sourced, with a high proportion of renewable resources, such as timber, straw, reed and hair, and produced by labour intensive methods, without costly industrial plant and without chemicals and pesticides. Still used for nearly 70% of the world's housing, such materials are usually biodegradable or environmentally benign. Where primary resources, such as clay and stone, were used, they were capable of repair or reuse, reducing whole-life cycle costs to a minimum. For example, Scottish slate, the traditional roofing material still widely used on historic buildings north of the Border, is now entirely reused, quarrying having ceased in 1955. Even primary traditional materials which consume resources in production and firing, such as lime, bricks and glass, were capable of recycling or reuse, extending their service life and reducing waste and environmental impact. The cyclical 'closed loop' ideal of ecological construction is exemplified by the use of lime mortar in traditional construction, as it actually fixes carbon dioxide when it sets, compared with Portland cement (OPC), the manufacture of which alone accounts for 3% of the 'greenhouse gas' produced worldwide.
The conservation and reuse of old buildings and sites should therfore be a priority of sustainable development. English Heritage pointed the way to a comprehensive approach in 1997 (Sustaining the historic environment) and the Scottish Office called the historic environment 'a finite and non-renewable resource' and has stated that 'Recycling existing buildings will mimimise the consumption of materials and energy used in demolition and development' (NPPG 18)(see Note).
Problems for historic buildings?
Historic building conservation has always had a social and ethical dimension, but there are still some conflicts between environmental and historic requirements, which require a balanced approach to building conservation, conditioned by the recognition of value and significance as defined in BS7913. For example, the conservation of some historic elements, such as staircases and panelled doors, may compel the use of virgin resources such as tropical forest timber, to enable repairs that are authentic and compatible, and preserve historic value. Solvent based glues and varnishes, lead and lead based paints may be required for similar reasons, despite their ozone depletion potential and toxicity.
When it comes to upgrading the thermal performance of existing buildings, it can be hard to introduce additional insulation unobtrusively without damaging historic plasterwork and joinery, and even when the insulation can be backed up by the use of recycled polypropylene vapour check membranes, the risk of interstitial condensation can be increased, resulting in accelerated timber and stone decay in traditional buildings. Traditional wall and roof constructions were originally designed to be tolerant of damp and to 'breathe' and dry out naturally; the modern approach involving dotting proprietary plastic ventilators over walls and roofs can disfigure historic buildings.
Similarly, the introduction of visually obtrusive 'trickle' vents after draught stripping historic windows seems irrational and uniquely valuable window glass and durable historic joinery can be needlessly destroyed when double glazing is installed. The recommended alternative of secondary double glazed units may spoil the appearance of historic panelling and mouldings if carried out carelessly, and may prevent the traditional timber shutters (in Georgian buildings) or heavy drapes (in Victorian) functioning to prevent draughts and provide insulation in a 'traditional' way.
Advantages of historic buildings
Nevertheless, historic buildings can offer important advantages from the point of view of sustainability. They were usually built to last, exploiting the natural advantages of the site, and already provide healthy toxin-free environments with high levels of user control. Intricate rooscapes may be suitable for unobtrusively sited solar heating panels and roof mounted photovoltaic arrays. Rambling cellars, disused stables and game larders may be used to conceal electrical storage batteries, rain water harvesting tanks, waste recycling bins and heat stores, not to mention low carbon condensing boilers, bio-boilers. Spacious attics may be able to house the air handling plant needed for energy saving heat recovery systems and air source heat pumps. Heating systems in large properties may already use zoned low temperature radiators fitted with thermostatic valves. Lighting can be upgraded with low energy fittings and programmable passive detectors to save electricity and reduce fire risk. Chimneys can provide 'passive stack ventilation' and conservatories and atria planting can contribute to indoor air quality while offering potential passive solar heat gains.
Historic buildings on country estates may be part of a sustainable economic and social structure, linking industry, agriculture and recreation, in which estate buildings are supplied with power generated by restored wind or water mills (for which read 'turbines') and are sustainably heated using their own coppiced wood or saw mill waste. Historic designed landscapes may have environmental 'capabilities', for using reed beds to process 'grey' waste water (from sinks, basins and baths), while the products of composting toilets and septic tanks may be reused on the land, binding the buildings back into nature.
Other conservation measures which encourage biodiversity, such as organic farming, planting native tree species and establishing wetlands may be possible. Bat and owl boxes can be provided and thatching crops may be grown on set-aside land. Many modern sustainable approaches are recognizable revivals of historic practices and estate offices with clear environmental policies may even be able to seek accreditation under ISO 14001 or the European Management and Audit Scheme (EMAS). Sustainability is entirely consistent with key conservation principles such as 'minimum intervention'.
A recent government -commissioned study proposes that the Houses of Parliament, designed by Sir Charles Barry and constructed between 1840-60, should be partly powered by a 35m high wind turbine and tidal power turbines in the adjacent River Thames. A recent report by The Bedford Park Society on Norman Shaw's famous arts and crafts estate, built between 1875 and 1914, encourages rainwater harvesting and fitting condensing boilers and PV panels, as well as solar water heating panels on south facing roof slopes.
Research and education
There is a pressing need for more research. The latest Building Regulations make some concessions for listed buildings, while schemes such as the Standard Assessment Procedure (SAP) used to measure thermal efficiency, offer the possibility of retaining historic windows by balancing energy efficiency gains elsewhere. Typically only 15 per cent of building heat losses are via the smaller windows usual in traditional buildings, with the highest proportion being lost through the roof, so that improvements to roof insulation are usually more effective and better value than either double glazing or secondary double glazing.
Understanding and imagination
Architects are professionally obliged to encourage their clients to use environmentally benign materials and energy efficient specifications, but sustainable development needs to be approached holistically, not in a short term, piecemeal or merely reactive way. The builders of the past were often far from naive; even humble traditional buildings were often constructed on traditonal sustainabe principles.
Many of our clients are concerned about the consequences of climate change for their buildings, and want to take steps to increase energy efficiency and reduce their carbon 'footprint', by introducing sustainable technologies. Our approach aims to combine awareness of historic building materials and construction methods with an informed overview of potential improvements which may be appropriate without impugning historic value. If you would like to discuss a particular project, please contact us.
References
BS EN ISO 14001 Environmental Management Systems - specification with guidance for use.BSI 1996.
Building the Future - A Guide to Building without PVC. Greenpeace, 1996.
Code for Sustainable Housing, a step-change in sustainable home building practice. 2006.
Energy and Climate Team: Friends of the earth, 1999.
Energy efficient school refurbishment, DES, 1991.
Energy Efficiency Best Practice Programme: BRECSU Greener Building and GreenPro. AECB, 1999.
Peyton, C Architectural Conservation and Sustainable Architecture: From Conflict to Conservation. Heriot-Watt University MSc Dissertation, 1996.
Planning and the Historic Environment: National Planning Policy Guideline (NPPG 18) The Scottish Office Development Department, April 1999.
Professor Anne Power, (LSE), speaking to the DCLG select committee inquiry into existing housing and climate change, 12 November 2007, said that reusing existing buildings would be 'cheap and relatively easy, and would have massive social as well as environmental benefits'. Quoted in Building Design, 16.11.07, p.4. Rodwell, D. Conservation and Sustainability in Historic Cities, Blackwell 2007.
Smales, Jonathan 'Eco-towns: pornography for planners' Building Design 16.11.07, p.21.
Sustainable Development, HMSO, 1994, quote from the 1987 Brundtland Report.
Sustainable Construction: A Scottish Persepective. A position paper written on behalf of the Scottish Office Construction and Building Control Group. Dr R Talbot, thirdwave (Scotland), October 1998.
Sustainable Development and Buildings. Report by the DETR Property Advisory Group. DETR 1998.
Sustaining the historic environment: new perspectives on the future. English Heritage, 1997.
Addresses
AECB (Association for Environment Conscious Building) Nant-y-Garreg, Saron, Llandysul, Camarthenshire SA44 5EJ Tel 01559 370908
BRECSU, BRE, Garston, Watford WD2 7JR Tel 01923 664258
Ecological Design Group, Faculty of Design, The Robert Gordon University, Garthdee Road, Aberdeen AB9 2QB Tel 01224 263713
SEDA (Scottish Ecological Design Association) 15 Rutland Square, Edinburgh EH1 2BE Tel 0131 229 7545
thirdwave (Scotland) Ltd, 20 Chambers Street, Edinburgh EH1 1JZ Tel 0131225 8833
Tweed Horizons Centre for Sustainable Technology, Newtown St Boswells, Melrose TD5 0SG Tel 01835 822992
ROBIN KENT
Robin Kent, a chartered architect accredited in building conservation, has directed conservation research projects for Historic Scotland and was involved in the government response to the UN Commission on Sustainable Development. One of the first architects to be listed in 'The Good Wood Guide', his consultancy aims to provide an holistic approach to historic building conservation.
NOTE | This article, which is based on an article published in the 2000 Conservation Directory, is copyright. The author is grateful for the assistance of Courtney Peyton, Richard Shorter, Gill Pemberton, Richard Atkins, Fionn Stevenson, David Stone and Mike Goodall. No responsibility is accepted for errors or omissions. It provides pointers to general principles and should not be viewed as a comprehensive guide. Each historic building will need separate consideration.