Tenements - Scotland’s
most sustainable
housing?
Matt Bridgestock
Director / Architect
Tenement Types
Post-war and modern - 40%
Sandstone (Pre-1919) - 38%
40% = 4 storey or more
4 in a block type - 20%
Mainly inter-war
Pre-1919 Tenements
23%
100+ years old
Low embodied
energy
Hard to treat
High proportion
fuel poverty
77%
Pre-1919 Tenements
Other Scottish Houses
Tenements deteriorate..
Physical issues
Resident Agreement
Costs and VAT
Climate: wind, rain, temperature
Exacerbated by Climate Change
Indoor climate, humidity, heating, ventilation
Poor previous repair or specification error
Wear, Tear and Weathering
Plant Growth
Vandalism, theft, abuse, noise
Requirements change...
Lifestyle
Technology
Aspirations
Heating in Tenements
Heating in Tenements
Heating in Tenements
How to help?
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Under One Roof
• Launch April 2016
• Website based manual
• Requires user testing
• Requires input into issues
• Contact
[email protected]
Milnbank HA
Can we modernise Tenements?
Can we modernise Tenements?
• 35% Milnbank Housing Associations stock
• Feature highly in MHA’s fuel poverty statistics
• Subject to both incremental and major refurbishments over 100 years
• Not listed but still important character
Staged Strategy
• BRONZE – 30% reduction in energy
• SILVER – 50% reduction in energy
• GOLD – Passivhaus (EnerPHIT) standard refurbishment
These strategies will consider physical refurbishment such as insulation,
heating systems, window replacement and draught proofing.
Airtightness
• Achieved:
• 17.13 ACH
• 14.62 m3/h/m2
Thermal Imaging
• Floor zone
• Windows / mullions
• Close doors
• Eaves
Literature Review
• Historic Scotland
• Changeworks
• Retrofit for the Future
• Passivhaus Institute
• Scottish Ecological Design
Association members
Strategies
• Airtight construction
• Renewed heating system
• Internal and external insulation
• Use of natural materials
• Ceiling / roof insulation
• Reducing thermal bridges
• Windows and doors
• Mechanical ventilation with heat
recovery
Variety of types
Type B - Top Floor
47m2 with 1 bedroom
Type C - Mid floor
83m2 with 3 bedrooms
Type A - Ground Floor
65m2 with 2 bedrooms
Roof
Existing insulation lifted, airtightness membrane installed and
lapped in to head of wall. 350mm warmcell insulation relaid.
U-value - 0.12
Build up:
- 680mm existing stone wall
- Plaster parge coat
- 100mm Woodfibreboard
- 10mm insulated plaster finish
Joists carefully sealed with airtightness
tape and lapped into plaster parge coat
Insulation carefully installed round joist ends
Maintain ventilation of roof space
Deadening reinstalled as floor is relaid
Plasterboard ceiling
Front wall detail
U-value - 0.30
Rear wall detail
U-value - 0.80
Build up:
- Existing stone wall
- 20mm insulated plaster finish
Refer to individual sheets for
internal works.
Plaster carefully installed round joist ends
Deadening reinstalled as floor is relaid
Plasterboard ceiling
Lead flashing along top of string
course to avoid excessive
moisture build up
Lift floor finishes on ground floor. Install 50mm
mineral wool on net between joists. Lay
airtightness membrane, lap into internal walls
and external plaster. Lay 18mm OSB and relay
floor finishes.
Uvalue 0.6
Client
Project
Title
Scale at A3
Drawing No
Milnbank HA
PassivTEN Research
Bronze Strategy
1:100, 1:20
[PP]01
Bronze
John Gilbert Architects
201 White Studios, 62 Templeton Street, Glasgow, G40 1DA | 0141 551 8383 | www.johngilbert.co.uk
Close actions
Wall stripped back to stonework, plater parge
coat applied, 100mm wood fibre board fitted with
mechanical fixings, finished internally with 10mm
insulated plaster and organic paint.
New lowered ceiling
in hallway
MVHR unit fitted in ceiling of
kitchen, new suspended ceiling
in kitchen and hall. Ducts to
each room.
Airtightness tape between windows and new plaster
MVHR intake and extract on rear wall
Lift floor
Insulation and plaster
airtight barrier
continued through floor
zone.
Wall stripped back to
stonework, 20mm insulating
plaster applied
Lift floor
Further investigation of solar thermal panels on roof required
Airtightness target of 3ach
Plaster continued through floor zone
TC-BRONZE
Type C Bronze Standard
Bronze
1:20
Flat actions
Client
Project
Title
Scale at A3
Drawing No
Milnbank HA
PassivTEN Research
Type C Bronze Strategy
1:200, 1:500
[PP]04
John G
201 White Studios, 6
New communal boiler in roof space, supplying hot
water and heating to each flat via duct in close. Fire
proof utility cupboard formed from timber frame and
supalux.
Build up:
10mm render system
250mm EPS insulation
Existing stone wall
20mm insulated plaster finish
Solar thermal panels mounted on south
facing roof
Plaster carefully installed round
joist ends
Roof
Existing insulation lifted,
airtightness membrane installed
and lapped in to head of wall.
350mm cellulose insulation laid.
U-value - 0.12
Deadening reinstalled as floor is relaid
Plasterboard ceiling
Roof may need extending at eaves
Rear wall detail
U-value - 0.13
Front wall detail
U-value - 0.30
- Existing stone wall
- Plaster parge coat
- 100mm Woodfibreboard
- 10mm insulated plaster finish
Refer to individual sheets for
internal works.
Lead flashing along top of string
course to avoid excessive moisture
build up
Insulation to run past ground floor into
ground to protect joist ends.
Lift floor finishes on ground floor. Install 200mm
polystyrene between joists. Lay airtightness
membrane, lap into internal walls and external
plaster. Lay 18mm OSB and relay floor finishes.
Uvalue 0.14
Client
Project
Title
Milnbank HA
PassivTEN Research
Silver Strategy
Silver
Close actions
Scale at A3
Drawing No
1:100, 1:20
[PP]05
John Gilbert Architects
201 White Studios, 62 Templeton Street, Glasgow, G40 1DA | 0141 551 8383 | www.johngilbert.co.uk
MVHR unit (Brookvent air cycle) fitted in ceiling
of kitchen, new suspended ceiling in kitchen and
hall. Rigid galvanised ducts to each room.
Wall stripped back to stonework, plater parge coat applied, 100mm
wood fibre board fitted with mechanical fixings, finished internally with
10mm insulated plaster and organic paint.
Airtightness tape between windows and
new plaster
New lowered ceiling
in hallway
MVHR intake and extract on rear wall
250mm polystyrene and render
applied externally.
Lift floor
Strip dry lining (where present) at
party walls, seal any gaps and
replaster. Plaster to be tied into
walls in flats above and below
along with being sealed to new
plaster work at external walls.
Insulation and plaster
airtight barrier
continued through floor
zone.
Wall stripped back to stonework, 20mm
insulating plaster applied
Lift floor
Plaster continued through floor zone
Communal heating system with solar thermal panels on roof
Airtightness target of 1 ach
TC-SILVER
Client
Type C Cutaway
Silver
Project
Title
Flat actions
Scale at A3
Drawing No
New communal boiler in roof space, supplying hot water and
heating to each flat via duct in close. Fire proof utility cupboard
formed from timber frame and supalux.
Build up:
10mm render system
250mm EPS insulation
Existing stone wall
20mm insulated plaster finish
Solar thermal panels mounted on south facing roof
Plaster carefully installed round
joist ends
Roof
Existing insulation lifted, airtightness membrane
installed and lapped in to head of wall. 350mm
cellulose insulation laid.
U-value - 0.12
Deadening reinstalled as floor is relaid
Plasterboard ceiling
Roof may need extending at eaves
Rear wall detail
Uvalue - 0.13
Windows all replaced with triple glazed,
passivhaus certified units. Spacetherm to
be used to form insulated Jambs and sills,
to be sealed into airtight barrier. Installed
uvalue to be 0.8
Front wall detail
U-value - 0.30
- Existing stone wall
- Plaster parge coat
- 100mm Woodfibreboard
- 10mm insulated plaster finish
Refer to individual sheets for
internal works.
Lead flashing along top of string course to
avoid excessive moisture build up
Insulation to run past ground floor into ground to
protect joist ends.
New windows and doors in close, replaced with
triple glazed, passivhaus certified units.
Spacetherm to be used to form insulated Jambs and
sills, to be sealed into airtight barrier. Installed
uvalue to be 0.8
Lift floor finishes on ground floor. Install 200mm
polystyrene between joists. Lay airtightness membrane,
lap into internal walls and external plaster. Lay 18mm
OSB and relay floor finishes.
Uvalue 0.14
Client
Project
Title
Milnbank HA
PassivTEN Research
Gold Strategy
Gold
Scale at A3
1:100, 1:20
Close actions
[PP]09
Drawing No
John Gilbert Architects
201 White Studios, 62 Templeton Street, Glasgow, G40 1DA | 0141 551 8383 | www.johngilbert.co.uk
MVHR unit (Paul Focus 200) fitted in ceiling of kitchen,
new suspended ceiling in kitchen and hall. Rigid
galvanised ducts to each room.
Passivhaus certified triple glazed windows installed and taped into airtight barrier
Wall stripped back to stonework, plater parge coat applied, 100mm
wood fibre board fitted with mechanical fixings, finished internally
with 10mm insulated plaster and organic paint. Window reveals to
be lined with Spacetherm to eliminate thermal bridging.
New lowered ceiling
in hallway
Airtightness tape between windows and new plaster
MVHR intake and extract on rear wall
Passivhaus certified triple glazed windows
installed and taped into airtight barrier
250mm polystyrene and render applied externally.
Lift floor
Insulation and plaster
airtight barrier
continued through floor
zone.
Strip dry lining (where present) at
party walls, seal any gaps and
replaster. Plaster to be tied into
walls in flats above and below
along with being sealed to new
plaster work at external walls.
Wall stripped back to stonework, 20mm insulating plaster applied
Lift floor
Plaster continued through floor zone
Communal heating system with solar thermal panels on roof
Airtightness target of 1 ach
TC-GOLD
Gold
Type C Gold Strategy
Flat actions
1:20
Gold
Bringing it together
drying out, however the product ‘GUTEX Thermoroom’ has recently been analysed by the Fraunhaufor IBP
and the data from their report has been used in this simulation.
For wood-based materials, moisture content should not exceed 20% mass-percent during a prolonged period. Fig 9 shows that the water content in the woodfibre reaches equilibrium in the first year at just over 14
M-% after drying out from the application of internal plaster, suggesting no significant risk of mould.
Build up:
- 680mm existing stone wall
- Plaster parge coat
- 100mm Woodfibreboard
- 10mm insulated plaster finish
Joists carefully sealed with airtightness
tape and lapped into plaster parge coat
Insulation carefully installed round joist ends
Fig 8 - Water Content in the Calsitherm board over five years
Deadening reinstalled as floor is relaid
Plasterboard ceiling
Replacement deafening to be
mix of sand and finishing
plaster.
Aiming for u-value of 0.30
WUFI Calcs - See Appendix
Thermal Bridging Fig 9 - Water Content in the woodfibre over five years
kraft architecture ltd | 280 high street | Glasgow | G4 0QT
t 01415522915 | f 08707061232 | [email protected] | www.kraftarchitecture.co.uk
registered in scotland no. 329135 | VAT No. 982896253 | director bruce newlands bsc(hons) pgdip riba rias
AECB The Sustainable Building Association | RIAS Advanced Sustainability Accreditation
Client
Project
201 White Studios, 62 Templeton Street, Glasgow, G40 1DA
Tel: 0141 551 8383
Web: www.johngilbert.co.uk
Rev.
Drawing Name
PassivTEN Research
Ammendment
Details
Proposed South Wall
Milnbank HA
Date
Drawing Status
Research
Drawing Scale
1:10
With moisture calcs
works in the loft, an divided them between each of the 8 flats in the close. This budget per flat is
included in the costs above. The overall budget for the common works for the gold (EnerPHit)
strategy is £131,262.65.
2)
Retrofit
Cost
(m
The following diagram shows the cost per square meter for each of the options:
11.4. Summary
Bronze
Silver
Gold
Flat Type B
Flat Type C
£1,500
£1,250
£1,000
£750
£500
£250
£0
Flat Type A
It is clear that the position of each flat greatly affects the cost of the work required with top and
bottom flats being more expensive than middle flats.
Retrofit Cost
Bronze
Silver
EnerPHit
Type A
£30,544
£54,042
£79,594
Type B
£18,738
£42,277
£65,468
Type C
£27,060
£48,493
£82,241
Inc VAT, Fees, Prelims and Contingency
this potentially includes owner occupied housing.
10.1. Heating Demand
The graph below shows the output of the proposals based on the relative heating demand
required for each flat type. This demonstrates how well the flat is insulated and how much heat is
required to keep the home at a constant temperature throughout the year. This is all shown in
kWh/m2.
Heat Demand
Type A
Type B
Type C
Heat Demand (kWh/m²)
500
375
250
125
0
Unimproved
Existing
Bronze
Silver
EnerPHit
It can be seen that Flat type A is the poorest performer consistently throughout the study, this is
due to its ground floor location and being relatively small compared to the area of exposed walls.
Flat C is the best performer as it is mid terrace with a heated flat above and below.
10.3. Annual Cost
Using current standard tariffs we have made an assumption about the energy costs for each flat
type with the retrofit measures in place. The graph below shows the total cost for each flat, the
size of the flat makes a significant difference to the total energy cost. We have not allowed for any
increase in fuel prices and over a 25 year period, price increases have been significant in the last
ten years and are likely to be significant.
Estimated Annual Cost
Type A (65m2)
Type B (47m2)
Type C (83m2)
2000
Total cost (£)
1600
1200
800
400
0
Unimproved
Existing
Bronze
Silver
EnerPHit
The graph below shows cost per meter square of floor area. It shows that the costs for each flat
converge at the silver and gold level, giving equal cost per square meter to all residents
Lessons learnt
• There are few examples of very
high standard retrofit in Scotland
• A strategy of improving airtightness,
with ventilation, has a more
significant effect than insulation
alone
• Photovoltaic cells can be added to
the roof of the properties and have
a simple payback period of 9 years
• The position of the flat has a
significant impact on the capital
cost of the refurbishment works
• Communal heating has a effect on
the cost of heating for tenants
• Silver and Gold standard carry a
very low risk of fuel poverty
• It is theoretically possible to meet
the EnerPHit standards with a
tenement close
• The costs of any of these upgrades
are significant. ECO funding in its
current state does not offer
significant assistance.
• There is a gap in the market for an
effective internal insulation product
for sandstone walls.
Thank you
Download the full report from our website - www.johngilbert.co.uk/
Or contact us for more information - Matt Bridgestock - 0141 551 8383