Transcript Builders book PTE/ZCH

SME Builder’s Book
Consultation
Tom Dollard
Head of Sustainability
Pollard Thomas Edwards
@dollardtom
@ptearchitects
[email protected]
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How to reduce the performance gap?
The Builder’s Book
Question / Answer session
Complete feedback form = drink!
Zero Carbon Hub – Performance Gap
• The government has challenged industry
to reduce the gap between the design and
the completed performance of buildings
• Many independent studies have shown
this gap to be from 60%-120% more energy
use than predicted.
• The Zero Carbon Hub has been
researching this throughout 2013-14, with
evidence gathered from 22 sites in the UK.
• The end of term report was issued in July
2014, and work continues......
The evidence gathering stage
A team of 4 people assessed each of the 22 sites across the UK including
small, medium and large developers
5 days of evidence gathering for each site:
• Interviews
• Design Review
• Construction walk-through
What did we find out?
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There is a significant performance gap – 15% - 50% higher than asbuilt SAP
No sites had the same window specification as SAP
Unaccounted thermal bridging is prevalent
Overheating is not considered
Part L accredited details not used correctly – knowledge Gap, not robust
The performance gap can be attributed to a large number of small errors
throughout the design and construction process
Common issues on site
• Windows set too far forward with no
overlap to cavity = thermal bridge
• Windows – incorrect specification
U value and G value worse than design
• Gaps in insulation – poor installation of
rigid board and injected insulation
LACK OF SITE TEAM
ENERGY PERFORMANCE
RELATED KNOWLEDGE
AND SKILLS AND/OR CARE
Example
• Windows pulled forward
from their design
positions
• Overlap with the cavity
closer well below the
minimum requirements
• Mastic or foam fill
interrupted by metal
fixing straps
Common issues on site
• Dense Blocks instead of aircrete blocks
• No insulation below DPC
• Beam and block floors - approx 20%
unaccounted thermal bridges and gaps
in installation
POOR INSTALLATION
OF FABRIC
Example
• Incorrectly fitted
insulation
• Detail when constructed
deviates from the design
Common issues on site
• Standard cavity closer on site but hiperformance insulated closer specified
• Cavities not consistent width so closer
does not fit tightly to block
• Soffit not insulated – heat loss
• Flat roof leaves 2 bricks thermal bridge
• Lintels different to design
LACK IF ADEQUATE
QUALITY ASSURANCE
ON SITE
Example
• Cavity insulation board
stopping short of cavity
closers at openings
• Gaps between boards
leading to increased heat
loss
Performance Gap(on site)
Products / Materials
Installation
incorrect/damaged / substituted
• Windows/ Doors
• Blocks
• Cavity closers/Lintels
• Insulation
• Services
Thermal Bridging
Thermal Bypass
Airtightness
Damp
Tolerance
Product checklist
Design vs Site findings
Linked to SAP categories
Builder’s book - Installation guide
How/what to check?
Sequenced diagrams/photos
Builder’s Book Contents
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Introduction (1 page)
House Section drawing and sequencing (1 page)
Common themes on site – top performance gap issues and how to improve (2 pages)
Site Posters – Fabric and Services - 18 sheets on specific areas/ junctions (18 pages)
Summary Checklist (1 page)
Fabric
Services/Renewables
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16.
1. First fix
2. Second Fix
Foundation/Ground Detail
Beam and Block Floor
Solid Floor
Door Thresholds
Cavity Wall – partial fill
Cavity wall – full fill
Floor Joists – intermediate floor
Party wall
Window cavity closer, cill and lintel
Window installation
Openings – Bay, oriel windows
External Doors
Eaves
Roof
Dryline/plaster
Finals
Any questions?
Feedback
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Consultation sessions on site?
How useful?
How to improve?
Please complete form and
scribble comments on posters
[email protected]
[email protected]
THANKYOU!!
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