Wall insulation & retrofit - Regensw
Wall insulation & retrofit : Inside, outside or the bit in between?
27th February 2013 Lucy Pedler The Green Register
The Green Register • Started in 2000 • Independent, self funded • Three core goals: • unbiased information • networking opportunities • Free-to-access Register of Construction Professionals
Heat loss through external walls
Internal, external or the bit in between?
Refurbishment • Over 80% of the 2025 building stock has already been built • 80% of 2050’s housing stock is already built • 60% of all buildings we will be using in 21st Century already exist • 40% of buildings standing in 2050 will pre-date 1985 when Part L was first introduced (BRE)
The age of existing housing stock 3% 17%
22%
Pre 1920 1921-1945 1946-1980
1980-present
21% 37%
mixed
Internal wall insulation • Pro’s: – Easier to install – Cheaper – No potential planning issues
• Con’s: – Loss of floor space – Potential loss of decorative features – Isolation of thermal mass – Difficult to avoid cold bridges
Knauf Insulation IWI System Three component system: • Composite studs – BBA Certified • Glass wool insulation – BBA Certified • Vapour check plasterboard – BBA Certified
Bedroom Front Wall - Before
Bedroom Front Wall - During
Bedroom Front Wall - After
Historic Scotland wall insulation trials •
Sword Street, Glasgow
Breathable insulating board on timber straps •
U-value 0.22 (40mm) / 0.36 (30mm)
Cellulose fibre (50mm) •
U-value 0.28
Hemp board (100mm) between timber straps •
U-value 0.21
External wall insulation • Con’s: – Detailing can be tricky – Expensive – Possible planning issues
• Pro’s: – No loss of floor space – No loss of decorative features – Makes best use of thermal mass – No cold bridges with careful detailing
Airtightness
Where heat is lost Total space heating costs in an airtight building may be as much as 40% less than in a leaky one (BRE, Airtightness in Commercial and Public Buildings 2002, p.3 )
‘We are at the stage where it is likely that any further increase in thermal insulation levels would be ineffective until levels of airtightness in construction have improved considerably.‘ Niall Crosson, Ecological Building Systems
Figure of heat losses per P. Jennings, ‘Airtightness in Buildings’ Building for a Future Winter ‘00/’01
Airtightness and insulation Air movement results in heat loss
An airtight layer reduces or eliminates air movement = minimal heat loss
Heat loss due to convection 1mm gap in the vapour check Inside temperature +20°C Outside temperature -10°C Pressure difference 20 Pa = wind force 2-3
1m
1m
Without gap:
140mm
Measurement: Institute of building physics, Stuttgart Source: DBZ 12/89
U-Value = 0,3 W/m2K
Heat loss due to convection 1mm gap in the vapour check Inside temperature +20°C Outside temperature -10°C Pressure difference 20 Pa = wind force 2-3
1m
1m
140mm
Measurement: Institute of building physics, Stuttgart Source: DBZ 12/89
Without gap: U-Value = 0,3 W/m2K With 1mm gap: U-Value = 1,44 W/m2K Performance reduced by a factor of 4.8 Draw a continuous line in section…
Build tight ventilate right: • Traditional buildings can have more than twice as much ventilation as necessary… • Draught proof windows and doors … • Block up chimneys- but leave damper or air brick • Replace timber ground floor with concrete (insulated) • Replacement double glazing • But don’t forget…..
Controllable ventilation: • BEWARE of air quality & moisture pollutant removal • Trickle vents in windows… • Extract fans in kitchens and bathrooms • Humidistat controlled fans in kitchens or • Occupancy controlled in bathrooms
Historic Scotland wall insulation trials •
Baseline U-value 1.1
Spacetherm aerogel • U values of 0.013 W/m K • very thin (5/10mm) for hard to treat situations • bay windows, walls with decorative features etc • Supplied as is or backed onto plasterboard or chipboard • silica gel is main ingredient
Resource Depletion & ‘Waste’ Minimisation What we do least of
What we do most of
Eco-retrofit measures for a Victorian terrace: • Ventilation – draught stripping and extract fans • aim for 50Pa pressure test of 7m3/m2 if nat. vent. • Roofs – loft insulation • Windows- low-E double argon filled /secondary glazing • Heating and hot water - condensing boiler (+solar..?) • Walls – external or internal insulation • Floors – under suspended timber floors or concrete floors • Cost approx. £10K • Carbon saved?
Comparison of CO2 Emissions After Additional Measures 160.0 140.0
kg CO2/m2 /year
120.0 100.0 Before
80.0
After
60.0 40.0 20.0 0.0 3-bed semi Georgian
3-bed semi Edwardian
Type of Home
2-bed terrace Georgian
2-bed terrace Victorian
United House Housing Association (with thanks) • • • • • • • • • • •
A-rated gas boiler central heating A-rated double glazing Internal wall insulation Floor insulation Draught proofing Low energy lighting Rainwater harvesting Low energy extract fans Energy monitors for residents Loft insulation top-up PV & solar thermal renewables
‘Value Carbon’ • United House developed method to analyse the energy/carbon leaks for an unimproved dwelling • Determines which retrofit techniques give the best value return £ spent/kgCO2 saved • Case studies : www.unitedhouse.net/projects
®
Value Carbon
(ref. United House Ltd) £22k
‘Tipping point’
£7k
2nd : (later) more difficult things eg. renewables
2
1 50%
So:
Cost
CO2 saved
1 property @ 70%
£22k
70%
3 properties @ 50%
£21k
150%
1st : quick wins
70%
Spot the difference...
27th February 2013 Lucy Pedler The Green Register
The Green Register • Started in 2000 • Independent, self funded • Three core goals: • unbiased information • networking opportunities • Free-to-access Register of Construction Professionals
Heat loss through external walls
Internal, external or the bit in between?
Refurbishment • Over 80% of the 2025 building stock has already been built • 80% of 2050’s housing stock is already built • 60% of all buildings we will be using in 21st Century already exist • 40% of buildings standing in 2050 will pre-date 1985 when Part L was first introduced (BRE)
The age of existing housing stock 3% 17%
22%
Pre 1920 1921-1945 1946-1980
1980-present
21% 37%
mixed
Internal wall insulation • Pro’s: – Easier to install – Cheaper – No potential planning issues
• Con’s: – Loss of floor space – Potential loss of decorative features – Isolation of thermal mass – Difficult to avoid cold bridges
Knauf Insulation IWI System Three component system: • Composite studs – BBA Certified • Glass wool insulation – BBA Certified • Vapour check plasterboard – BBA Certified
Bedroom Front Wall - Before
Bedroom Front Wall - During
Bedroom Front Wall - After
Historic Scotland wall insulation trials •
Sword Street, Glasgow
Breathable insulating board on timber straps •
U-value 0.22 (40mm) / 0.36 (30mm)
Cellulose fibre (50mm) •
U-value 0.28
Hemp board (100mm) between timber straps •
U-value 0.21
External wall insulation • Con’s: – Detailing can be tricky – Expensive – Possible planning issues
• Pro’s: – No loss of floor space – No loss of decorative features – Makes best use of thermal mass – No cold bridges with careful detailing
Airtightness
Where heat is lost Total space heating costs in an airtight building may be as much as 40% less than in a leaky one (BRE, Airtightness in Commercial and Public Buildings 2002, p.3 )
‘We are at the stage where it is likely that any further increase in thermal insulation levels would be ineffective until levels of airtightness in construction have improved considerably.‘ Niall Crosson, Ecological Building Systems
Figure of heat losses per P. Jennings, ‘Airtightness in Buildings’ Building for a Future Winter ‘00/’01
Airtightness and insulation Air movement results in heat loss
An airtight layer reduces or eliminates air movement = minimal heat loss
Heat loss due to convection 1mm gap in the vapour check Inside temperature +20°C Outside temperature -10°C Pressure difference 20 Pa = wind force 2-3
1m
1m
Without gap:
140mm
Measurement: Institute of building physics, Stuttgart Source: DBZ 12/89
U-Value = 0,3 W/m2K
Heat loss due to convection 1mm gap in the vapour check Inside temperature +20°C Outside temperature -10°C Pressure difference 20 Pa = wind force 2-3
1m
1m
140mm
Measurement: Institute of building physics, Stuttgart Source: DBZ 12/89
Without gap: U-Value = 0,3 W/m2K With 1mm gap: U-Value = 1,44 W/m2K Performance reduced by a factor of 4.8 Draw a continuous line in section…
Build tight ventilate right: • Traditional buildings can have more than twice as much ventilation as necessary… • Draught proof windows and doors … • Block up chimneys- but leave damper or air brick • Replace timber ground floor with concrete (insulated) • Replacement double glazing • But don’t forget…..
Controllable ventilation: • BEWARE of air quality & moisture pollutant removal • Trickle vents in windows… • Extract fans in kitchens and bathrooms • Humidistat controlled fans in kitchens or • Occupancy controlled in bathrooms
Historic Scotland wall insulation trials •
Baseline U-value 1.1
Spacetherm aerogel • U values of 0.013 W/m K • very thin (5/10mm) for hard to treat situations • bay windows, walls with decorative features etc • Supplied as is or backed onto plasterboard or chipboard • silica gel is main ingredient
Resource Depletion & ‘Waste’ Minimisation What we do least of
What we do most of
Eco-retrofit measures for a Victorian terrace: • Ventilation – draught stripping and extract fans • aim for 50Pa pressure test of 7m3/m2 if nat. vent. • Roofs – loft insulation • Windows- low-E double argon filled /secondary glazing • Heating and hot water - condensing boiler (+solar..?) • Walls – external or internal insulation • Floors – under suspended timber floors or concrete floors • Cost approx. £10K • Carbon saved?
Comparison of CO2 Emissions After Additional Measures 160.0 140.0
kg CO2/m2 /year
120.0 100.0 Before
80.0
After
60.0 40.0 20.0 0.0 3-bed semi Georgian
3-bed semi Edwardian
Type of Home
2-bed terrace Georgian
2-bed terrace Victorian
United House Housing Association (with thanks) • • • • • • • • • • •
A-rated gas boiler central heating A-rated double glazing Internal wall insulation Floor insulation Draught proofing Low energy lighting Rainwater harvesting Low energy extract fans Energy monitors for residents Loft insulation top-up PV & solar thermal renewables
‘Value Carbon’ • United House developed method to analyse the energy/carbon leaks for an unimproved dwelling • Determines which retrofit techniques give the best value return £ spent/kgCO2 saved • Case studies : www.unitedhouse.net/projects
®
Value Carbon
(ref. United House Ltd) £22k
‘Tipping point’
£7k
2nd : (later) more difficult things eg. renewables
2
1 50%
So:
Cost
CO2 saved
1 property @ 70%
£22k
70%
3 properties @ 50%
£21k
150%
1st : quick wins
70%
Spot the difference...
