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A - Base building: Steel-framed, air-conditioned office
Basic information
Gross internal floor area: 11,700 m²
Form: Six storeys high and 15 m deep on plan
Construction: Steel frame of 44 kg/m²
Substructure: 200 mm groundbearing slab, bearing on to 2.5 m deep pad foundations
Roof: Flat, Sarna single-membrane proprietary roofing system with parapets
External walls: Mostly wall cladding with reconstituted stone. Ten per cent is polyester powder coated aluminium curtain-walling, fully glazed to clear height with double-glazed low-emissivity glass
Window frames: Aluminium for about 60% of clear height
Windows: Double-glazed, low-emissivity glass
Air-conditioning: Chilled beams with displacement ventilation in a raised floor plenum of 400 mm deep
Lifts: Three passenger and one goods
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Capital costs (£) (excluding fees)
Substructure £544,010
Structure £2,013,435
External envelope £3,090,609
Internal divisions £528,842
Finishings and fittings£2,805,140
Mechanical £3,707,744
Electrical and communications £2,486,371
Lifts £594,093
Preliminaries, overheads and profit £2,680,646
Design and construction contingency @ 8% £1,475,933
Total £19,925,000
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Annual energy consumption (£)
Space heating £9,457
Cooling and fans £32,872
Lighting £14,165
Other energy costs £35,194
Total (over 30-year period) £91,688
D - Environmental impact
ÌýÌýCO2 outputEcopoints
ÌýQuantityRatingTonnesRatingTotal
Steel frame with composite floors
Pad foundations263 m³0.3181.535.31,393.90
Steel frame515 t0.76391.4115,665.00
Note: The above ratings accept the steel industry’s calculation methodology (previously questioned)
Hot-dip galvanized steel permanent formwork9.215 t1.3412.3511101.37
140 mm lightly reinforced concrete1290 m³0.37477.35.36,837.00
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Total for steel frame option excluding operationÌýÌý963Ìý13,997
CO2 produced over 30 years30 years77523,250ÌýÌý
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CO2 total emissions for steel frame option including operationÌýÌý24,213ÌýÌý
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Insitu concrete frame and floors
Pad foundations440 m³0.31136.45.32,332.00
Reinforced concrete columns323 m³0.38122.745.31,711.90
Reinforced concrete beams59 m³0.3822.425.3312.7
(Taken to perimeter, but can be avoided)ÌýÌýÌýÌýÌý
Reinforced concrete floors2675 m³0.381,016.505.314,177.50
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Saving 200 mm wall height per level (approx)–341 m²0.1-34.11.1–375.10
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Total for insitu concrete option excluding operationÌýÌý1,264Ìý18,159
CO2 produced over 30 years30 years71821,540ÌýN/A
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CO2 total emissions for insitu concrete option including operationÌý22,804ÌýÌýÌý
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Summary of changes
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Overall extra for concrete option excluding building operationÌý301 (up 31%)Ìý4,162 (up 30%)Ìý
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Overall saving for concrete option including building operation 1,409 (a 6% saving on total energy costs)ÌýÌýÌýÌý