Case Study 3 - Hybrid Renewable Energy, Reclaimed Materials
Shettleston Housing Association, Glenalmond Street, Glasgow
| Type: | New build, timber frame, terrace housing and flats | |||
| Number of units: | 16 | |||
| SAP rating: | nomial 100 (160 calculated) | |||
| U-values: | 0.14 Wm2C roof | |||
| 0.22 Wm2C walls | ||||
| 0.22 Wm2C floor |
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| Fuel costs: | £1.80 pw (predicted) | |||
| Works costs: | £748,793 total |
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| Unit cost: | £47,704 |
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| Completion date: | July 1999 | |||
| Contacts | Client: | Shettleston Housing Association | Nick Ronan | 0141 763 0511 |
| Architect: | John Gilbert Architects | John Gilbert | 0141 551 8383 | |
| Builder: | Robinson and Davidson | Nicol Milne | 01387 267423 |
The site is close to public transport and shops and sits in the middle of a traditional housing area in the east end of the city. The L-shape layout of the housing on this brownfield site creates a safe access and semi-private children's play area in front of a south-facing 3 storey block of flats and adjoining row of housing and cottage flats facing east and west. The scheme is almost car-free with only 4 existing on-street car bays and an individual bay for the wheelchair standard house. Privacy for the housing and front gardens is maximised using the semi-private space in front where car parking would normally be expected. The varied housing mix of 1,2 and 3 bedrooms includes convertible loft spaces, barrier-free standards and internal flexibility. This promotes the concept of lifetime housing.
Figure 3.1 Overall view of the scheme showing car-free play area, glazed atrium, solar panels and careful landscaping. Untreated larch cladding is used for the upper storey housing.
Key Features
Energy
High insulation, solar panels, geo-thermal power, pre-heated ventilation, passive ventilation, micro-climate modification, draught lobbies
Wall insulation: 160mm Warmcel cellulose
Roof insulation: 300mm Warmcel cellulose
Floor insulation: 75mm polystyrene
Combined geo-thermal/solar panel heating: heating for hot water is provided by pre-warmed water (12°C) piped up from an old coalmine which is 100 metres below the site. The water temperature is boosted by a heat pump and stored in a large insulated storage tank (10,000 litres). The temperature is additionally topped up by 36 m2 of solar panels. The water is used to supply low temperature radiators (45°C) and warm water via storage cylinders. This is charged as a basic service charge within the rent for communal heating. Tenants can raise the temperature of the hot water if required using electric immersers which avoids the need for expensive metering controls. Low temperature heating is very suitable for well insulated properties and avoids risks of scalding by touch. Initial monitoring of the heat store shows that it is performing better than expected. There are many old mineworkings in parts of Scotland making this form of heating potentially accessible on sites situated over them.
Pre-heated ventilation: the carefully designed air-tightness of the dwellings allows for deliberate air intake through the void between the roof tiles and sarking using a small fan which pressurises the houses slightly. This reduces draughts as well as providing solar pre-heated fresh air using very simple and cheap technology.
Passive ventilation: a proprietary system allows hot stale air to rise through ducts to the roof ridge vent without fans, reducing energy and maintenance costs.
Draught lobbies: these are glazed and provided to the front and rear doors of the houses creating additional amenity space as well as a thermal buffer to the main building.
Micro-climate modification: heat-loss through the fabric has been minimised by reducing wind velocities around the buildings using extensive planting and external structures.
Resource Conservation
Reclaimed and recycled materials, waste minewater re-used
A serious attempt was made in this scheme to use as much reclaimed or recycled materials and products as possible and within cost. It should be noted that sourcing of reclaimed materials and products was time consuming and not always cheaper despite the obvious environmental benefits. The following items were successfully incorporated into the scheme:
- recycled newspaper for insulation material
- recycled wood chippings in the Truss Joist Macmillan webbed beams
- reclaimed brick from site for boundary walling
- reclaimed stone setts and paviours for front gardens
- reclaimed concrete paviours for rear gardens
- some reclaimed floor timbers (wastage from previous schemes)
- some reclaimed bathroom fittings
- some reclaimed railings from another scheme
Attempts made to source more reclaimed brick from Scotland failed due to lack of time and information. Cooled minewater discharged from the heat pumps is stored in a greywater tank and used to feed all the WC cisterns in the housing.
Other Relevant Aspects
Healthy Housing
Comprehensive environmental specification
- The environmental specification has carefully minimised toxicological effects by specifying the following:
- untreated larch battens and cladding from Perthshire (reducing preservative treatment and transportation)
- calcium silicate external board panels (minimises vapour pollution)
- Warmcel insulation(100% recycled waste paper)
- timber windows and other external timber treated with water based preservative rather than traditional Copper Chrome Arsenate (CCA) which is toxic
- low odour paints and stains which are natural resin oil-based (no toxic emissions)
- untreated softwood cill boards and skirtings in preference to MDF (no formaldehyde)
- natural rubber flooring in communal atrium
- use of locally made bricks (minimises transportation and associated pollution)
Social and Management
Focus group to develop sustainable themes, communal atrium
Future tenants were identified and encouraged to join a focus group which developed some of the sustainable themes and gave a greater understanding of the issues involved. The group also participated in the choice of certain fittings for the housing including: showers, glazed doors, tiling, decoration, storage, kitchen units and floor covering finishes.
The south-facing 3 storey communal atrium to the flats was designed to encourage neighbours to meet and sit in the warm, pleasant environment. Internal planting beds have been provided to encourage communal planting with beds watered using only water provided via a communal tap (Figure 3.2 - 3.3).
Figure 3.2 Communal stair showing communal planting area.
Figure 3.3 A tap is thoughtfully provided for the internal communal planting areas.
Costs and maintenance
The scheme attracted sponsorship from Forward Scotland to pay for the grey water supply, solar air ventilation and solar panel system. All other costs were within Scottish Homes HAG guidelines.