Annat Road

PH2 7JF

Perth, United Kingdom


Owner

The Gannochy Trust
Main Office, Pitcullen Crescent, Perth, PH2 7HX
admin@gannochytrust.org.uk
01738620653

User

Tenants of the Gannochy Trust

Contact Details

Roger Curtis
Historic Environment Scotland
roger.curtis@hes.scot
44 1316688621

Other Information

Visits
The building can be viewed from the street, but no inside access is possible

Related publications
Historic Environment Scotland Refurbishment Case Study 20
© HES
This project was the thermal upgrade of a traditional building in Perth dating to 1927. This included improvements to the insulation of the walls, floor and roof as well as better natural ventilation. Natural and vapour open materials were prioritised. The project was a success and improved the U-values of individual elements considerably. This project was used to inform further refurbishment of other buildings on the estate.
Energy performance Primary Energy:
285 kWh/m2.y

Climate Zone Cfb

Altitude 33

HDD 2393

CDD 0

Protection level Not listed

Conservation Area:
No

Level of Protection:

Building age 1900-1944

Year of last renovation:
2014

Building use Residential (urban)

Secondary use:
NA

Building occupancy:
Permanently occupied

Number of occupants/users:
4

Building area Net floor area [m²]: 77,0

Building typology:
Detached house

Number of floors:
1

Basement yes/no:
No

Number of heated floors:
1

Gross floor area [m²]:
81,0

NFA calculation method:
Useful area (ro)

Construction type
Stone masonry wall

External finish:
Exposed stonework

Internal finish:
Plastered (on substructure)

Roof type:
Pitched roof

+ MORE - LESS
© HES
© HES
Radiant heat panel in the bathroom © HES
Radiant heat panel in the bathroom © HES
Area of completed clay plaster © HES
Area of completed clay plaster © HES
Window detail retained during refurbishment © The Gannochy Trust
Window detail retained during refurbishment © The Gannochy Trust
Living room with clay paint and cupboard, after refurbishment © The Gannochy Trust
Living room with clay paint and cupboard, after refurbishment © The Gannochy Trust
Living room with cupboard before the refurbishment © The Gannochy Trust
Living room with cupboard before the refurbishment © The Gannochy Trust
Kitchen before the refurbishment © The Gannochy Trust
Kitchen before the refurbishment © The Gannochy Trust
General view of Annat Road © HES
General view of Annat Road © HES
Plaque showing importance of ventilation © HES
Plaque showing importance of ventilation © HES
Area of mould discovered above lowered ceiling © HES
Area of mould discovered above lowered ceiling © HES
Bathroom details © The Gannochy Trust
Bathroom details © The Gannochy Trust
Kitchen © The Gannochy Trust
Kitchen © The Gannochy Trust

RENOVATION PROCESS

Architecture

BUILDING DESCRIPTION

Annat Road is a single story red sandstone cottage, built in 1927 in a vernacular style with focus on ventilation, high room volumes and natural light. It is part of a development by AK Bell to provide good quality housing for his workers. It is now managed as affordable housing and let to tenants by the Gannochy Trust.
Urban context
Annat Road is part of a development of the same style cottages, all run by the Gannochy Trust, slightly outside Perth. As such, it is part of a typical planned neighbourhood of the early 20th century.

HERITAGE SIGNIFICANCE

ELEMENTS WORTHY OF PRESERVATION
This is one of a number of cottages worth preserving as a whole ensemble. In this development, particular emphasis was put on natural ventilation by the builder AK Bell, as shown by the bronze plaques attached to the cottages. As such, these ideas are worth preserving.
Heritage Value Assesment
Part of a whole development of detached dwellings, using features considered important for the occupants health at the time. The building is likely influenced by the 'Garden City Movement' of the early 20th century, aimed at providing housing with green space. It represents a good example of homes built by factory owners for their employees to offer better quality living conditions than was the norm at that time.

State of repair

Conditions of the envelope
The building was dated in terms of services and decoration as well as areas of damp and mould growth. Structurally, the state of repair was acceptable.
Description of pre-intervention building services
Mains gas. Gas boiler; wet heating system to radiators. Passive ventilation, with blocked previous vents.

Aim of retrofit

Renovation
key themes shown by Historic Environment Scotland through this work are adaptation to climate change, energy efficiency and the management of damp. This was done by upgrading the insulation of the building and reinstating the passive ventilation systems. The insulation materials were chosen to be compatible with traditional features, such as the sandstone wall and the lath and plaster interior finish.
Was the intervention planned following a step-by-step approach?
The renovation of Annat Road was a whole house approach looking all building elements and improving the performance of these areas where practicable. An emphasis was placed on reinstating the natural ventilation. Most measures had been trialed before in refurbishments done by HES 2008-2017 - See Technical Paper 25, refurbishment project review.
Lessons learned
The project showed that particularly walls and floors could be insulated while retaining traditional materials and finishes. While not a traditional material, the water based foam used has performed well.
Stakeholders Involvement
Public sector
Historic Environment Scotland (HES)
Longmore House, Salisbury Place, EH9 1SH
Energy Consultant
Glasgow Caledonian University
Indoor Climate and Health Research Centre, School of the Built & Natural Environment, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4 0BA
Other
The Gannochy Trust
Main Office, Pitcullen Crescent, Perth, PH2 7HX
Tools used
Was the renovation process done following a specific methodology? No
Energy calculation Reduced Data SAP was used as part of the EPC process.
Hygrothermal assessment In-situ monitoring of relative humidity in the North-West and South-East walls was undertaken by an independent consultant.

RETROFIT SOLUTIONS

External Walls

Solid masonry; cement bonded 500mm thick.

Solid masonry; cement bonded 500mm thick.

Interior cavity between masonry and lath and plaster was filled with insulation material

The water based foam is able to fill the void effectively, leaving the original traditional external and internal wall finishes intact. The cured foam is vapour open and capillary active, minimising the risk of condensation damage.

U-value (pre-intervention) [W/m2K]: 1,1 W/m²K U-value (post-intervention) [W/m2K]: 0,41 W/m²K
More Details
Original wall build-up
Stone - Red sandstone, coursed rubble, cement mortar:
500 mm
Air gap :
40 mm
Plaster - Traditional lath and plaster:
25 mm
Retrofitted wall build-up
Stone - As original:
500mm
Insulation - Water based expanding foam injected into cavity:
40 mm
Plaster - Retained traditional lath and plaster:
25 mm


Other interventions

ROOF

GROUND FLOOR

ROOF

The roof was insulted in a warm roof method in order to provide usable space as well as gains in energy efficiency. Wood fibre board was selected for this insulation as it fits the natural material ethos of the project and is able to buffer humidity in the roof spaces. Due to the fibrous nature of the wood fibre board, a vapour permeable paint was used to consolidate the surface of the material.

The material chosen is fully compatible with the traditional materials on the roof, as it is fully breathable and vapour open. By being able to buffer moisture, it can help to control the humidity in the roof space.

U-value (pre-intervention) [W/m2K] 1 U-value (post-intervention) [W/m2K] 0.13
More Details
Original roof build-up
Slate - Traditional slate :
25 mm
Bitumen - Under slate bitumen felt:
1 mm
Other - Timber sarking boards:
25 mm
Retrofitted roof build-up
Slate - As original:
25 mm
Bitumen - Under slate bitumen felt as original:
1 mm
Other - Timber sarking board as original:
25 mm
Other - Wood fibre board insulation layer:
100 mm
Other - Vapour permeable paint:
1 mm
GROUND FLOOR

The living room and bedrooms on the ground floor had suspended timber floors. In these rooms, the floorboards were carefully lifted in sections and set aside for re-use, to enable the installation of wood fibre board insulation material. After insulation, the floorboards were re-laid as far as possible. About 15% of new timber was necessary for this.

As the solum was dry and spacious, this provides ventilation under the floor. A breathable material is therefore needed to allow some exchange between the floor and the solum. Wood fibre board was chosen for these characteristics and due to its ability to buffer moisture. In addition to this, the ventilation grilles were cleared to allow air circulation.

More Details
Original groundfloor build-up
Finish - Timber flooring on top of floor joists:
20 mm
Floor joists - Timber floor joists:
100 mm
Solum - Packed earth with legacy debris:
600 mm
Concrete slab - Base underneath house:
100 mm
Retrofitted groundfloor build-up
Finish - Floorboards were left in situ where possible. Original floor was reused where lifted.:
20 mm
Insulation - Wood fibre material was secured between joists.:
100 mm
Solum - Debris cleared, particularly around ventilation grilles.:
600 mm
Concrete slab - Base underneath house:
100 mm

HVAC

VENTILATION

VENTILATION

Ventilation sources, such as the chimneys in the bedrooms were opened. Additionally, a grille was fitted above the door to the internal lobby to improve conditions to this unheated space. Additionally, the existing extraction fan in the bathroom was improved and the lowered ceiling removed.

The ventilation methods were all either reinstatement of an older version or similar to designs found in traditional houses. In the bathroom, removing the lowered ceiling returned the room to its previous air volume.

More Details
Original roof build-up New ventilation system
Type ventilation system Older buildings generally require to have air naturally circulating. Existing flues and hearths can play an important role, as well as opening windows and similar. Extraction fans can enhance this as necessary.
Type flow regime NA (Natural)
Heat recovery No
Humitidy recovery No
Nominal power 0 kW
Electric power 0,0 kW
Control system Occupiers

Energy Efficiency

Energy Performance
Energy performance certificate: Energy Performance Certificates (EPC's) 's were carried out before and after the refurbishment.
Voluntary certificates: No
Energy Use
Heating
Primary Energy 285 kWh/m2.y

Primary Energy
Consumption_estimation_Calculation_method: Steady state simulation (e.g. EPC, PHPP)
Documents:
EPC.pdf
Post-refurbishment EPC statement

Consumption_estimation_Including_DHW: Da
Consumption_estimation_After: 285 kWh/m2.y
Measured Parameters
Internal Climate
Type_of_monitoring: Continuous
Description: The internal condition was monitored after the refurbishment. This included internal monitoring of temperature and humidity, particularly in the loft space. This was due to the risk to the wood fibre board insulation. Monitoring of the IAQ is planned.

External Climate
Type_of_monitoring: Continuous
Description: To accompany the above indoor monitoring, the conditions on the outside was also measured. The temperature and humidity were monitored, as well as the surface temperature of the N-W facing and S-E facing walls.

Construction
Type_of_monitoring: Continuous
Description: The humidity was monitored at the interface between insulation and the solid wall between 2014 and 2018. The parameters measured within the wall were relative humidity and temperature. This was to check for potential risk from interstitial condensation. The measured internal and external conditions are part of this report.
Documents:
Post-Invention Monitoring Annat Road_2.pdf
Post-intervention Monitoring Report


Internal Climate

Temperature

The insulation measures have improved the internal climate. Additionally, better ventilation and higher rooms due to the removal of a false ceiling have improved the indoor air quality.

Indoor Air Quality

The ventilation through the chimneys in the bedrooms has improved the indoor air quality. This is an aspect of the project that was a particular focus. A project to monitor the IAQ is planned in the near future.

Costs

Financial Aspects

The funding was provided by the owners, as well as a refurbishment grant by Historic Environment Scotland. The total works to the cottage included standard upgrade items such as new kitchen, bathrooms and electrical wiring, not covered by this case study. All the work had to be carefully specified and instructed.

Investment Costs
Total investment costs
£17,007.08 (total)
Amount includes: This figure includes insulation of the walls, roof and ground floor, lifting and relaying of the floor boards, as well as implementing of ventilation methods in the kitchen, bathroom and bedrooms.
Running Costs
Lifecycle cost
No

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