I work as a consultant engineer for AECOM, and international technical consultancy. My work covers energy and sustainability in the build environment, and I am part of the AECOM Sustainable Development Group. The group is one of the oldest in the country dating back to the early 90s, and currently works extensively with the Government, helping with policy and regulation, with local authorities supporting the development of local policy and contributing to evidence bases, and working on building projects, both new and refurbishment. In this presentation I will be mulling over sustainability, and how it applies to the historic buildings sector. This is a fast moving time in the field of sustainability, but there is much debate as to what the word actually means. I think that considering the wider meaning of the term in relation to buildings, and in particular historic buildings, is important to help us understand the true meaning of the word.
Andrew turton 2012
Sustainability and Historic Buildings: An alternative viewpoint on sustainability and the practicalities and optionsAndrew Turton 21st February 2012
• Member of the Shape East Design Review panel• Associate Director at AECOM‟s sustainable development group based in Cambridge• Expert in energy and sustainability, working with both government on policy, and project work
• Existing buildings will remain dominant in the future – pressure to refurbish and upgrade• Need to make buildings more resilient to climate change and rising energy prices• “Historic and special buildings” are a small fraction (374,000 listed buildings in UK) overall, but will experience the same pressures• Conservation status and special designations can be seen as restrictive, but there are many opportunities presented by historic buildings• How sustainable are historic buildings and how can they be improved further?
• First BREEAM „Outstanding‟ rating. Features include a biomass heating.
• Code level 6 „Zero Carbon‟• Biomass pellet boiler, solar thermal, and photovoltaic panels.• High levels of insulation• Good day lighting and natural ventilation• A “technological” approach to sustainability
• AECOM design (structural design and services)• Constructed from locally felled sweet chestnut. Materials informing structure, similar to many historic timber structures.
• AECOM project. New visitors centre with community, exhibition, education, and meeting areas.• High efficiency combined with sensitive material selection.• Enhancing and increasing viability of existing historic building.• Project was awarded the Civic Trust Award and Michael Middleton Special Award 2011.
• AECOM Project (mechanical, electrical, acoustics, sustainability ).• Novel use of existing services• Minimal impact on existing fabric and strucutre.
• Sustainable buildings can take many forms.• There are many different aspects to sustainability: – Historical understanding – Social and community benefits – Impact on the environment – Energy consumption and CO2 emissions – Materials and construction
Brundtland Report (1987) “meeting the needs of the present without compromising the ability of future generations to meet their own needs”Brundtland commission set up by UN in 1983 headed by GroHarlem Brundtland, former PM of Norway.
• Building Research Establishment Environmental Assessment Methodology• Rates buildings “Pass” to “Outstanding” taking into account: Health and wellbeing Management Energy Water Pollution Materials Ecology Transport Waste• Mostly used on new buildings but refurbishment scheme being introduced. How will historic buildings be included?• Does this really address sustainability in the round?
“The most sustainable building is one which isn’t built” “The most sustainable building is one which already exists”Perhaps we should be making better use of our existingvaluable assets?How can we help them become more sustainable and adapt tofuture climates (both environmental and economic!)
• Need to include the history, operation, future, and wider aspects of the building and uses in any assessment.Important considerations:• Social and historical importance• Existing structures which have worked hard and can be adapted for future use• Generally designed to operate passively / naturally• Long lasting with inherent quality• Simple, natural materials and construction methods
• Poor use and occupancy levels – do buildings meet the need of occupiers and are good quality environments offered? Are they suitable for modern uses?• High maintenance costs – what can be done to limit maintenance costs and improve performance?• High energy costs – older buildings typically inefficient. Energy efficiency and CO2 reduction is a key challenge to all existing buildings. Need to become more energy secure.• Marketing – there can be a premium for sustainable buildings which offer tenants and owners benefits. A niche market perhaps for sustainable historic buildings?
Need to consider1. How the building was originally designed to operate.2. What are the current main failings are. Often due to poor refurbishment or modification.3. What level of aspiration (and funding!) is available. Have a vision and plan!4. The significance of the building, and the opportunities and constraints this may provide.• Understanding the basic operation and ethos of an historic building is vital....
Modern construction• National / international supply chains• Highly processed materials.• Complex components and construction detail important for performance.• Short lifetimes common (60 years).Traditional construction• Locally sourced natural materials• Inherent quality and durability of materials and construction.• High cost of labour and labour intensive methods leads to long life and low maintenance.
• Older buildings designed to breathe: – Removes the need for impermeable materials (they werent available!) – Provides a healthy atmosphere – Allows use of natural materials – Reliable – no design detail or operational requirements.• Majority of problems in older buildings are due to the prevention of breathing. Many common remediation methods make matters worse.• Need to consider natural materials and historic techniques when repairing and refurbishing.
• Natural ventilation. Sliding sash windows very effective• Natural light – narrow floor plans combined with tall windows• No cooling required – cross ventilation and high thermal mass Remove modern internal partitions to allow cross ventilation Maintain and improve existing sash windows Inform occupants on how to use windows Fit high efficiency controlled lighting
• Historic buildings often characterised by: – Natural materials – clay, stone, timber, lime, metal, straw – Local materials – Long life materials and structures• Need to ensure renovation is compatible with original techniques• The building already exists! No new materials are required.• Construction waste is about 1/3 of UK annual waste.
• A measure of how much energy is used in creating a building.• Modern house: – Typically 50 tonnes embodied carbon to build – Saves 3 tonnes per year over existing house – 17 year payback• Modern efficient buildings have a significant carbon footprint upfront.• How can we reduce operational emissions from historic buildings? Possibly the biggest challenge!
• Maintain natural and passive performance. Back to basics.• Improve energy efficiency• Reduce operation and maintenance costs• Provide a good internal environment for users• Sustainable long lasting maintenance• Remember – there is much that can be done before touching the building fabric. Management, waste, transport, procurement, food, water, etc... Many of these are free or low cost options!• But energy efficiency is possibly one of the biggest challenges for the
1. Improving energy efficiency Increasing cost and2. Using energy efficiently smaller returns3. Renewable and low carbon energy supply
• Conservation for fuel and power• Exemptions for: – Listed – Conservation areas – Scheduled ancient monuments where alterations would unacceptably alter character or appearance. Important to understand the significance of the building and the limitations and opportunities this may pose.
• Generally poor in old buildings – external walls the biggest problem.• Some modern materials may be suitable (eg glass wool).• Natural alternatives include Hemp, sheeps wool, straw, flax. Becoming increasingly available.
• External insulation: Need to consider visual appearance. Could be possible with existing rendering or cladding.• Internal: Consider impact on existing finishes such as plasterwork. Can potentially cause serious problems with condensation and thermal bridging.• Generally very difficult and needs careful consideration.• Most opportunities presented at major renovation.
• Floors – Suspended – can insulate but need to consider ventilation – Solid – need to use breathable materials such as limecrete and hempcrete.• Roofs – Relatively simple using a range of materials. Ventilation of roof timbers vital. – Can be incorporated under new coverings – consider vapour control and prevention of condensation (particularly for metal coverings)
• Cement – inflexible and impermeable.• Causes frost damage, damp, and cracking
• Otherwise known as draught proofing - not to be confused with breathability• Can be a considerable source of heat loss in older buildings (although not as bad as some newer buildings!)• Can control loss though windows, doors, chimneys, floors by around half.• Very low cost and effective.• Reduces energy demand and improves perceived comfort.
• Windows – often a significant architectural feature.• Options available for double glazing retrofit (eg „slimlite) but not always practical.• Heat loss through glazing can be large, but savings may be relatively small compared with other inefficiencies.• Drivers for glazing replacement are more often maintenance, condensation, draughts, dow n-draughts. Solve these first!
Try not to replace entire windows for efficiency purposes uPVC....NO!Provide adequate controlled ventilation to reduce condensationMaintain and improve existing windowsUse replacement double glazed units where possible and no adverse impact (but respect historic quality of old glass)Install secondary glazingReplacement – most traditional types available.
• Significant potential for savings through good controls and management (>10% should be achievable)• Link the control strategy to building type and use – consider occupancy patterns. Who needs heat and when?• Monitor energy consumption before and after making changes. Don‟t forget water too!• Heating controls – zoning, internal temperature control, weather and load compensation, distribution temperatures, dual systems.• Make someone responsible!• Provide simple instructions and educate building users!
• First target – good controls and high efficiency condensing gas boiler• Low carbon technologies: – Combined heat and power (suited to high heat loads) – Community heating schemes (district heating). Talk to others!• Renewable technologies – Biomass boilers. Suited to high temperature and constant heat demands. Consider space and operation requirements. – Heat pumps (air source and ground source). Require low temperature systems (eg underfloor). Operate best in highly efficient buildings (and so probably not many historic buildings!)
• What are the opportunities provided by the building: – Chimneys (services routing, stack ventilation) – Service tunnels. Can these be refurbished? Need to consider asbestos.• External services – consider how these can be carefully routed. What is the visual impact of pipework and cabling.• Is surface mounting less destructive than routing though fabric? Consider historic flooring and ceilings.• Retrofit can be challenging – existing systems modified and extended over time. Potentially many systems in one building.
• Make sure efficiency is addressed first!• Photovoltaic and solar thermal prime options.• Significance – balance between integrated solutions for visual reasons vs non-integrated for limiting impact on fabric• Potential for reducing visual impact – installation on flat roofs, behind parapets, in valleys.• Free standing installations?• May be “permitted development”
• Think carefully about the opportunities and constraints.• If in doubt, ask! – Local conservation officer – Architects specialising in historic buildings – Engineers with historic expertise• Engage early with conservation officers and building control, and planning.• Always make use of contractors with suitable experience. Be careful of hi-tech quick fixes.• Think long term – consider the lifecycle costs and future maintenance.• Research and think carefully before making a decision.