Case Study 8 - Rehabilitation without Timber Treatment, Landscaping
Fairfield Housing Co-operative, Phase 3, Fairfield Estate, Perth
| Type: | Rehabilitation, tenement flats | |||
| Number of units: | 53 | |||
| SAP rating: | Pre-SAP | |||
| U-values: | 0.17 Wm2C roof | |||
| 0.3 Wm2C walls | ||||
| 0.3 Wm2C floor |
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| Fuel costs: | n/a | |||
| Works costs: | £1,998,445 |
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| Unit cost: | £37,706 |
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| Completion date: | 1992 | |||
| Contacts | Client: | Fairfield Housing Co-operative | Grant Ager | 01738 630738 |
| Architect: | Gaia Architects | Howard Liddell | 0131 557 9191 | |
| Builder: | Hall and Tawse, Scotland Ltd | 01224 6931550 |
Figure 8.1 Extensive low level beech hedging is easy to maintain and provides an effective micro-climate when combined with taller indigenous trees.
The rehabilitated tenement block, built in 1936, is close to public transport and shops and lies at the heart of a peripheral housing estate. The scheme is Phase 3 out of the seven phases completed so far. The layout and mix have been altered to build in greater diversity resulting in 1, 2 and 3 bed flats.
Key Features
Healthy Dwellings
Natural timber treatment and environmental specification
Figure 8.2 The dense planting gives significant shelter to the housing and provides 'free' insulation to the walls.
Timber preservative treatment has been avoided in the roof by significantly increasing the amount of ventilation going through the roof void which prevents moisture accumulating and causing rot. This treats the cause of the problem rather than the symptom which is the rot itself. The timber preservation consultants, Hutton and Rostron Ltd1 carried out an extensive rot survey before recommending this measure after all existing rot was removed.
All internal and external finishes are non-toxic with timber frame windows specified throughout.
The Site
Landscaping and extensive micro-climate modification
A major feature of the rehabilitation of the whole estate was the comprehensive landscaping and planting of communal spaces and streetscape at the beginning. The planting of indigenous tree species such as rowan, together with deep beech hedging and other defensive planting has resulted in a significantly more sheltered micro-climate which helps to reduce energy costs as well as creating a high quality amenity space providing cleaner, fresher air due to the oxygenation and particle filtration of the planting.
Other Relevant Aspects
Energy
High insulation
Wall insulation: 100mm Rockwool
Roof insulation: 200mm Rockwool
A major objective for the client was to reduce fuel poverty in this scheme. Insulation has been added internally to all external walls. All-electric 'Total Control' heating has been specified to minimise capital and maintenance costs. This is justifiable given the small amount of heating required and the future option of using alternative renewable sources of energy to supply the electricity.
Resource Conservation
Minimum specification for maximum gain
The specification for internal insulation not only saves on capital costs but also significantly reduces the embodied energy tied up in the rehabilitation work by omitting insulated overcladding with its associated high energy costs. Externally, the renderwork has been carefully surveyed and patched only where necessary. A vibrant coat of paint has lifted the exterior appearance without the need of extensive re-modelling of the facade.
Social and Management
Community commitment
Fairfield Housing Co-operative was formed to take over 300 houses from Scottish Homes in 1989. It has a very strong tenant-run committee which is democratically elected. The small number of staff servicing the co-operative work out of an office in a converted flat in the middle of the co-operative housing. This has resulted in a very close working relationship between management and tenants with the result that the estate has developed a distinctive community feeling with very low turnover of tenancies, demonstrating high satisfaction. The tenants. committee has been committed from the outset to high environmental standards after an initial visit to other environmental buildings to see for themselves what could be achieved, and encouragement from their architects.
Costs and Maintenance
All anticipated costs were contained with an agreed budget with Scottish Homes. Although there are some additional maintenance costs associated with the soft landscaping, these have been minimised using easy to care for planting, and justified on grounds of quality of space and health and wellbeing. Redundant chimneys were either removed to reduce maintenance costs or re-used for ventilation purposes.
Footnotes
^ 1. Hutton and Rostron Environmental Investigations Ltd. use
unique investigation and treatment measures to minimise
disturbance to the building fabric.
Netley House, Gormshall, Surrey GU5 9QA
Tel: 01483 203221