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1
English Heritage research and
perspective
• Hearth & Home
Windows
Walls
Bolsover
Other opportunities
• Green Deal
focus on some aspects
Assessing the thermal performance
of sash windows
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RESEARCH
Windows
U-values for windows:
Replacement windows: U-value
≤ 2.0 W/m²·K
Windows in extensions: U-value
≤ 1.8 W/m²·K
Doesn’t apply to repairs
GCU Environmental Chamber – Test Aperture
Test Window
3.0m
Insulated Panel
(Extruded Polystyrene, thickness = 300mm)
Cold Warm
Add curtain,
blind,
secondary
glazing, etc.
2.4m
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2. ShuttersU value 2.0 Heat loss reduced by 62%
4. Modern roller blind
U value 3.3 Heat loss reduced by 27%
5. Modern roller blind with tighter fit to window
U value 3.1 Heat loss reduced by 36%
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Estimates of the whole window U-values and reduction in
total heat loss through the window with various options
Option
Reduction in
heat loss
U-value
(W/m2K)
Whole window with single glazing 4.3
Heavy curtains 41% 2.5
Shutters 58% 1.8
Modern roller blind 38% 2.7
Roller blind with low E film on outside 57% 1.9
Honeycomb blind 51% 2.1
Secondary glazing 58% 1.8
Secondary glazing and shutters 62% 1.6
Other tests
• air pressure
• thermal imaging
• condensation
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Lauriston Place, Edinburgh
Potential improvements
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Metal windows being tested
Cast iron windows
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Isothermal glazing
Walls
• 220mm solid brick
• Data collected
includes heat flux,
temperatures &
images
• Results positive
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New Bolsover Model Village
… assessing the actual thermal performance of traditional
dwellings and the effectiveness of improvements…
•200 Grade II listed buildings
•conservation area
•curtilage of Bolsover Castle
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EH test
house
N
Original windows
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East elevation West elevation
Physical condition
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Damp Survey
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Baseline data
• in-situ U value tests
• air pressurisation
tests
• thermal transmission
value
• co-heating test
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Room Element In-situ U-value
W/m2K
CIBSE/Build Desk
values W/m2K
Target values
Building Regs.
retained
elements
Living room Front elev (E) wall 1.75 2.09 0.3
Living room Gable wall 1.21 1.41 0.3
Living room Floor (timber susp) 1.19 - 0.25
Hall Gable wall 1.65 2.09 0.3
Kitchen Floor (concrete) 0.28 - 0.25
Kitchen Rear elev (W) wall 1.36 2.09 0.3
Main bedroom Ceiling (north) 0.49 0.5 (75mm) 0.16
Main bed Ceiling (south) 0.18 0.2 (200mm) 0.16
Main bed Front elev (E) wall 1.76 2.09 0.3
Main bed Gable wall 1.78 2.09 0.3
Main bed Double glazing 2.71 (glazing) 2.85 1.6
Rear bed Rear elev (W) wall 1.74 2.09 0.3
Rear bed Single glazing 5.23 (glazing) 5.75 1.6
Results
Heat losses
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Training
Next phase
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Opportunistic
• Cambridge
• Cornwall
• Sheffield
• Energy Saving Trust
The Green Deal 2012
• new financing
mechanism
• pay for themselves
• workshops
• appropriate measures
will vary
• process
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The Process
• GD Advisor establishes GD Plan
• GD Provider secures funding & arranges installation of measures by accredited installers
• Capital cost repaid via levy on fuel meter collected by energy company over 25 years
• Debt is attached to building not occupant
The Green Deal Assessment
• Assessment carried out
by an accredited GDA
• The GDA will produce
- EPC recommending an
appropriate package of measures
that may be financed with GD
- further assessment of how
occupants use energy in their
home/business
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The assessment & older buildings
• Understand limits of methodology and where further
expertise is needed – rdSAP and SAP
• Recognise potential hard to treat issues e.g. narrow cavities
• Knowledge of local building stock - covered in NOS
• Sensitive to householder/ business preference – e.g. where
looking to retain traditional features
• Ultimately, all measures will need to be signed off by authorised GD installer
Issues
• incentives
• building condition
• nature of construction
• upgrading existing fabric
• repairs
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Relevant research
• Environmental
monitoring
• Damp Towers
• Casework
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Challacombe Church, Exmoor
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Way forward
• Refer to EH advice
• Exemptions/special
considerations
• Grading assessors
• Assessment toolkit
• Repair/upgrading advice
