Transcript Andrew Turton 2012 - PeterboroughBuildingsinNeed

Sustainability and Historic Buildings:
An alternative viewpoint on sustainability
and the practicalities and options
Andrew 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 Gro
Harlem Brundtland, former PM of Norway.
ENVIRONMENTAL
SOCIAL
ECONOMIC
• 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 existing
valuable assets?
How can we help them become more sustainable and adapt to
future 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 consider
1. 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 weren't
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.
• BREATHING DIAGRAMS
Cement render
Concrete floors
Impermeable internal
finishes (gypsum plaster,
tiles, paints)
Injected damp proof
courses
Sealing
Bare brickwork
Lime mortar re-pointing
Lime render
Suspended wooden
floors
Lime / hemp floors
Natural finishes (lime
plaster, “eco” paints)
Good ventilation
• 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
building.
1. Improving energy efficiency
2. Using energy efficiently
3. Renewable and low carbon
energy supply
Increasing
cost and
smaller
returns
• 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, sheep's 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)
• Two complimentary materials
• Low embodied carbon
• Structural, insulation, render, infill.
• 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, down-draughts. Solve these
first!
Try not to replace entire windows for
efficiency purposes
uPVC....NO!
Provide adequate controlled
ventilation to reduce condensation
Maintain and improve existing
windows
Use replacement double glazed
units where possible and no adverse
impact (but respect historic quality of
old glass)
Install secondary glazing
Replacement – 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.
• http://www.helm.org.uk/
• www.greenspec.co.uk
• www.buildingconservation.com
• http://www.brebookshop.com/