CASE STUDY 1: The Old Apple Store, Stawell, Somerset
water heating, passive solar design, improvements upon this, with two Lessons learnt:
wood pellet boilers, rainwater of the houses achieving 2.57 and • Designing for compliance with
harvesting 2.17 cu m/h@50pa respectively code level 5 or 6 requires a holistic
approach to design and a very
External fabric: Thermally Insulation: Recycled newspaper detailed knowledge and careful
efficient timber cassette shell that between the timber studs, consideration of CSH criteria at the
was considered replicable for future and woodfibre boards which earliest design stage
projects. U-value of 0.14W/sq m K wrapped the complete building • Design detailing for the code can
envelope. Sheep’s wool be time consuming and labour
Roof: Engineered ‘I’ beams, insulation was used for inter-floor intensive if the overall design
filled with recycled newspaper insulation concept is complex
insulation with 100mm woodfibre • The administration of the code
with OSB top and bottom and an Key problems: Complex process should be considered
internal vapour control layer to the architecture hindered the build from the outset of a project and
Project brief: Originally designed underside of the OSB. U-value of process and also the low air- suitable systems implemented
to meet the criteria for Ecohomes 0.12W/sq m K permeability. with contractual obligations for
Excellent, its final target was code suppliers/contractors to provide
level 5 Ground floor: Constructed from Build cost: information relevant to the
concrete planks with 150mm foam • Excluding land costs and fees: agreed design and construction
Development type: Five new private insulation under a 50mm screed £1,375 per square metre – higher programmes
family homes – two detached with 50mm edge upstands. U-value than standard expectations • Assembling and educating a
four-bedroom houses, and three of 0.15W/ sq m K • Water management and dedicated construction team is
three-bedroom terraces renewable energy systems costs: an essential to meeting the challenges
Windows/doors: Triple-glazed FSC additional £170 per square metre of higher level code developments,
Construction type: Glulam Frame certified with U-values of 1.2W/ sq particularly when new materials
with Orientated Strand Board m K. External doors U-value of 1.1 Sales value: Between £275,000 and and construction methods are
(OSB) W/ sq m K £399,000, or £2,238 to £2,615 per being used
square metre, Local comparable
Key sustainability features: Air permeability: Target was 3 cu sales prices are £2,045 per square Occupant feedback: None yet
Photovoltaic cells, solar thermal m/h@50pa; tests have shown metre available
CASE STUDY 2: CO2 Zero, Bristol
Project brief: The first private mineral wool plus 100mm foam Key problems:
residential development in the UK sheet insulation. U-value of 0.10 • Space constraints on-site created
and the first live-work development W/ sq m K particular difficulties in installing
to reach code level 5 renewable technologies
Floor: 50 per cent 99BS concrete • The implications of the thickness
Development type: Nine two- slab with 165mm foamed sheet of the external insulation used in
bedroom, three storey live-work insulation and FSC raised timber the new build system were not fully
units floor. U-value 0.10 W/ sq m k appreciated by the subcontract
teams
Construction type: Solid cross Windows/doors: Roof-lights
laminated timber panels with (U-value 1.1W/ sq m K) and duplex Build cost: Excluding land and fees
external insulation and render. windows (U-value 0.70W/sq m K) – £1,428 per square metre, about a • Preparing well co-ordinated
Aluminium sheet roof with upstand are triple-glazed, low–e windows 15 per cent increase over traditional construction and delivery
seam and curved profile with thermally broken frames. build methods management programmes at
Shop front windows are double- an early stage is essential to
Key sustainability features: glazed with thermally broken Sales value: Estimated at about understand and avoid likely
Passive solar design, low flow rate frames (U-value of 1.2W/ sq m £250,000 or c.£2,974 per square difficulties
sanitaryware, rainwater recycling, K). Doors are fully insulated, in metre (net internal). Sales prices for • Some specialist MVHR suppliers
low energy LED lighting, PV array, thermally broken timber frames similar properties in the area were in the UK do not yet seem to
biomass pellet boiler, low energy with U-value of 1.0W/sq m K when not available appreciate the considerable
rated white goods, FSC timber, unglazed and 1.4W/sq m K with potential that their systems have
green roof and MVHR vision panels. Lessons learned: for use in smaller scale, highly
• There needs to be a greater insulated developments
External fabric: Solid cross Air-permeability: Test results were understanding of the implications • There needs to be a greater
laminated timber panels with 1.2 cu m /h@50pa for the first of detailing to achieve low U-values awareness of zero carbon and the
290mm mineral fibre bat external complete dwelling and low levels of air-permeability implications of building to high
insulation. U-value of 0.10W/ • The use of specialist sub- levels of the CSH throughout the
sq m K Insulation: Units constructed using contractors for design and construction industry
prefabricated solid cross timber installation can be beneficial in
Roof: Aluminium sheet, upstand laminated panels with external terms of ensuring successful Occupant feedback: None yet
seam, curved profile with 200mm insulation and render delivery available
www.cibsejournal.com August 2009 CIBSE Journal 29
CIBSEaug09 pp26-31 Homes.indd 29 23/7/09 14:53:29
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