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| Revisions to standard U-values of construction elements | ||
| Construction element | U-values 1995 Revision (W/m2°C) | U-values 2001 Revision (W/m2°C) |
| Pitched roof | 0.25 | 0.16-0.20 |
| Flat roof | 0.25* | 0.25 |
| Walls, including basement walls | 0.45 | 0.35 |
| Floors, including ground floors and basement floors | 0.45 | 0.25 |
| Semi-exposed walls and floors | 0.60 | n/a |
| Windows, roof windows and doors (metal frames) | 3.30 | 2.20 |
| Windows, roof windows and personal doors (timber or PVCu frames) | 3.30 | 2.00 |
| Rooflights | 3.30 | 2.20 |
| Vehicle access and similar large doors | 0.70 | 0.70 |
| Source: Approved Document Part L (1995) and Approved Document L2 | ||
| *0.45 if there is no loft space | ||
| Business park scheme | |||
| Base scheme compliant with Approved Document Part L (1995) | |||
| Element cost (£) | cost/m2 gfa (£) | % of total cost | |
| Substructure | 258,600 | 71.24 | 8.97 |
| Pad and strip foundations, 150 mm thick suspended ground slab, below slab drainage, excavation, site preparation | 2100 m2 @ £106 | ||
| Masonry wall construction below DPC; DPC; insulation | 150 m2 @ £240 | ||
| Frame and upper floors | 275,200 | 75.81 | 9.55 |
| 300 mm thick, insitu concrete flat slab, insitu concrete columns and shear walls | 1900 m2 @ £112 | ||
| Structural steel framing | 48 t @ £1300 | ||
| Roof | 310,800 | 85.62 | 10.78 |
| Pitched roof; roof trusses; felt; battens; accessories | 1745 m2 @ £95 | ||
| Sarnafil to flat roof; plywood decking; insulation, vapour barrier, accessories | 890 m2 @ £100 | ||
| Allowance for fascia boards, soffit cladding etc | item @ £56,000 | ||
| Stairs | 56,000 | 15.43 | 1.94 |
| Mild steel main staircase with steel/timber handrails, external escape stairs | item @ £56,000 | ||
| External walls, windows and doors | 475,800 | 131.07 | 16.51 |
| Cavity wall construction; facing brick and blockwork | 920 m2 @ £150 | ||
| Miscellaneous works; additional dampproofing, blockwork plant enclosures | item @ £22,500 | ||
| Punchhole windows, entrance screen, double door sets; sealed double-glazed units | 855 m2@ £310 | ||
| Insulated louvres to plant rooms | 335 m2 @ £150 | ||
| Internal partitions | 80,900 | 22.29 | 2.81 |
| Blockwork to cores | 736 m2 @ £42 | ||
| Glazed partitions, WC cubicles and panelling | item @ £50,000 | ||
| Internal doors | 41,800 | 11.52 | 1.45 |
| Veneered doors and frames to office areas and riser cupboards, glazed doors (average rate) | 44 @ £950 | ||
| Wall finishes | 60,300 | 16.61 | 2.09 |
| Wallboard, decorations | 2080 m2 @ £29 | ||
| Floor finishes | 199,900 | 55.07 | 6.94 |
| Raised floors, carpets, skirtings; to office areas | 3350 m2 @ £47 | ||
| Floor finishes to common areas; tiles, carpets, screeds, skirtings | item @ £42,400 | ||
| Ceiling finishes | 78,700 | 21.68 | 2.73 |
| Metal and plasterboard suspended ceilings; paint finishes | 3350 m2 @ £20 | ||
| Ceiling finishes to common areas; suspended ceilings and painted plasteboard | item @ £11,700 | ||
| Furniture and fittings | 19,300 | 5.32 | 0.67 |
| Vanitory units, mirrors, window boards, signage | item @ £19,300 | ||
| Sanitary fittings | 10,500 | 2.89 | 0.36 |
| Allowance for sanitary installation | item @ £10,500 | ||
| Disposal installations | 23,000 | 6.34 | 0.80 |
| Rainwater and soil and waste drainage | item @ £23,000 | ||
| Water installations | 26,800 | 7.38 | 0.93 |
| Hot and cold water installation | item @ £26,800 | ||
| Heating, air treatment and ventilation | 231,400 | 63.75 | 8.03 |
| Heat source and LPHW installation in plant rooms | item @ £87,600 | ||
| LPHW distribution on office floors; insulation | item @ £111,000 | ||
| Miscellaneous local space heating and ventilation installations | item @ £32,800 | ||
| Electrical installations | 209,600 | 57.74 | 7.27 |
| Allowance for LV supply, LV switchpanel and sub-mains distribution | item @ £24,600 | ||
| Lighting and small power installation | 3630 m2 @ £50 | ||
| Miscellaneous electrical installations | item @ £3500 | ||
| Lift installations | 30,000 | 8.26 | 1.04 |
| Lifts, 1 passenger lift | item @ £30,000 | ||
| Protective installations | 2,300 | 0.63 | 0.08 |
| Earthing and bonding | item @ £2300 | ||
| Communications installations | 43,200 | 11.90 | 1.50 |
| Communication installations generally; fire detection and alarm | 3600 m2 @ £12 | ||
| Builders’ work in connection | 29,000 | 7.99 | 1.01 |
| Allowance for builders' work | item @ £29,000 | ||
| Preliminaries and contingencies | 419,000 | 115.43 | 14.54 |
| Contractor's overheads, site establishment and site supervision; allow 12% | item @ £296,000 | ||
| Contingency sum; allow 5% | item @ £123,000 | ||
| Construction cost – building only | £2,882,100 | £793.97 | 100 |
| City office scheme | |||
| Base scheme compliant with Approved Document Part L (1995) | |||
| Element cost (£) | cost/m2 gfa (£) | % of total cost | |
| Substructure | 4,500,000 | 137.20 | 7.72 |
| Bored insitu piling; reinforced insitu concete wall and slab construction to two level basement; excavation | 2500 m2 @ £1800 | ||
| Frame | 3,480,000 | 106.10 | 5.97 |
| Structural steel framing; board fire protection | 2320 t @ £1500 | ||
| Upper floors | 1,334,800 | 40.70 | 2.29 |
| Composite floor slabs; 130 mm thick lightweight insitu concrete on metal decking | 28,400 m2 @ £47 | ||
| Roof | 798,800 | 24.35 | 1.37 |
| Double-glazed utitised roof glazing | 110 m2 @ £800 | ||
| Composite roof slabs; 130 mm thick lightweight insitu concrete on metal decking; two layer felt roofing | 2250 m2 @ £160 | ||
| Reinforced concrete roof slabs at ground floor level to basements; smoke vents | 520 m2 @ £290 | ||
| Plant bases, platforms, access ladders and balustrading | item m2 @ £200,000 | ||
| Stairs | 300,000 | 9.15 | 0.51 |
| Precast concrete staircases, stainless steel balustrading and handrails | 60 @ £5000 | ||
| External walls, windows and doors | 10,879,600 | 331.70 | 18.66 |
| Double glazed curtain walling; full-height glazing, aluminium framing at 1.5 m centres; external doors | 12,500 m2 @ £710 | ||
| Aluminium metal panel soffit | 260 m2 @ £420 | ||
| Insulated louvres to plant rooms | 720 m2 @ £480 | ||
| Open louvre screens to roof level plant areas | 1060 m2 @ £330 | ||
| Allowance for doors, canopies, stone plinths and skirtings, colunm casings, ventilator grilles, access doors and ladders, security grilles | item @ £1,200,000 | ||
| Internal partitions | 1,952,500 | 59.53 | 3.35 |
| Basement blockwork, upper floor dry-lined partitions, glazed screens to ground floor | 27,500 m2 @ £71 | ||
| Internal doors | 931,000 | 28.38 | 1.60 |
| Steel and veneered doors and frames to plant rooms and office areas; various fire ratings (average rate) | 490 @ £1900 | ||
| Wall finishes | 620,000 | 18.90 | 1.06 |
| Glazed wall panelling, panelling and tiling to WCs, paint finishes | 15,500 m2 @ £40 | ||
| Floor finishes | 1,694,800 | 51.67 | 2.91 |
| Raised floors to office areas | 23,800 m2 @ £46 | ||
| Screeds; natural stone floor tiling; ceramic floor tiling; plant room finishes; paint finishes; generally | item @ £600,000 | ||
| Ceiling finishes | 1,298,600 | 39.59 | 2.23 |
| Metal suspended ceilings; to office areas | 23,800 m2 @ £47 | ||
| Plasterboard suspended ceilings; paint finishes | item @ £180,000 | ||
| Furniture and fittings | 1,500,000 | 45.73 | 2.57 |
| Vanitory units, cubicle partitions, blinds, mirrors and general fittings | item @ £1,500,000 | ||
| Sanitary fittings | 120,000 | 3.66 | 0.20 |
| Allowance for sanitary installation | item @ £120,000 | ||
| Disposal installations | 340,000 | 10.37 | 0.58 |
| Rainwater, soil and waste and condensate drainage | Item @ £340,000 | ||
| Water installations | 190,000 | 5.79 | 0.33 |
| Hot and cold water installation | Item @ £190,000 | ||
| Heating, air treatment and ventilation | 7,578,000 | 231.04 | 13.00 |
| Gas installation | item @ £40,000 | ||
| Heat source and LTHW installation in plant rooms | item @ £380,000 | ||
| Chilled water and condensor water installations | item @ £1,620,000 | ||
| Air handling plant | item @ £360,000 | ||
| Supply and extract ductwork | item @ £260,000 | ||
| Pipework and ductwork insulation generally | item @ £590,000 | ||
| Fan coil units, on-floor LTHW and chilled water distribution pipework, insulation, supply and extract ductwork | 32,800 m2 @ £110 | ||
| Miscellaneous local space heating and cooling installations | item @ £220,000 | ||
| Miscellaneous local ventilation installations | item @ £500,000 | ||
| Electrical installations | 3,411,200 | 104.00 | 5.85 |
| Allowance for HV switchgear, transformers and sub-mains distribution | item @ £740,000 | ||
| Lighting installation | 32,800 m2 @ £63 | ||
| Small power installation | 32,800 m2 @ £16 | ||
| Miscellaneous electrical installations | item @ £80,000 | ||
| Lift installations | 3,030,000 | 92.38 | 5.20 |
| Lifts, 8 passenger lifts, 2 passenger/firefighting lifts, 1 goods lift | item @ £3,030,000 | ||
| Protective installations | 984,000 | 30.00 | 1.69 |
| Protective installations generally; lightning protection, sprinkler installations, dry risers and hose reels | 32,800 m2 @ £30 | ||
| Communications installations | 754,400 | 23.00 | 1.29 |
| Communication installations generally; fire detection and alarm, telecommunications, CCTV and access control | 32,800 m2 @ £23 | ||
| Special installations | 1,964,000 | 59.88 | 3.37 |
| Building management system | 32,800 m2 @ £30 | ||
| Allowance for window and atrium cleaning systems, standby generation | item @ £980,000 | ||
| Builders’ work in connection | 920,000 | 28.05 | 1.58 |
| Allowance for builders' work | item @ £920,000 | ||
| Preliminaries and contingencies | 9,716,000 | 296.22 | 16.67 |
| Contractor's overheads, site establishment and site supervision; allow 15% | item @ £7,287,000 | ||
| Contingency sum; allow 5% | item @ £2,429,000 | ||
| Construction cost – building only | £58,297,700 | £1,777.39 | 100 |
| Business Park scheme | ||
| Enhancements to scheme to comply with Approved Document L2 | ||
| Option 1 – high performance glass | ||
| Element cost (£) | cost/m2 gfa (£) | |
| Construction cost of base scheme | £2,882,100 | £793.97 |
| Substructure | 7,200 | 1.98 |
| Extra for: enhanced insulation to edges of ground floor slab to meet new U-values; 50 mm thick | 240 m @ £30 | |
| Roof | 38,500 | 10.61 |
| Extra for; additional insulation to pitched roof; between and across rafters; 150 mm thick | 1745 m 2 @ £18 | |
| Extra for; additional insulation to flat roof; 150 mm thick | 890 m 2 @ £8 | |
| External walls, windows and doors | 45,300 | 12.48 |
| Extra for; enhanced insulation to cavity wall construction; 150 mm thick; including works below DPC | 1070 m 2 @ £1 | |
| Extra over for high performance glazing to windows and doors; clear super neutral glass to outer pane | 855 m 2 @ £40 | |
| Extra for; enhanced insulation to plant room louvre panels and cladding; (encased insulation, overall thickness 130 mm) | 335 m 2 @ £30 | |
| Furniture and fittings | 15,400 | 4.24 |
| Window blinds | 855 m2 @ £18 | |
| Heating, air treatment and ventilation | -2600 | -0.72 |
| Saving for; reduced boiler capacity due to improved thermal performance of building fabric; reduction of 15 kW; reduction related to perimeter heat losses only | item @ -£4600 | |
| Extra for; allowance for variable speed drives to boiler pumps | item @ £2000 | |
| Special installations | 5000 | 1.38 |
| Extra for; allowance for energy metering to main plant and Builders’ work in connection | 400 | 0.11 |
| Extra over costs of additional builders’ work | item @ £400 | |
| Preliminaries and contingencies | 23,600 | 6.50 |
| Contractor’s overheads, site establishment and supervision; allow 12% | item @ £13,100 | |
| Allowance for provision of log books and enhanced manuals | item @ £5000 | |
| Contingency sum; allow 5% | item @ £5500 | |
| Construction cost – building only including costs of Part L compliance | £3,014,900 | £830.55 |
| Extra over costs of Part L compliance | £132,800 | £36.58 |
| Overall percentage increase | 4.4% | |
| City office scheme | ||
| Enhancements to scheme to comply with Approved Document L2 | ||
| Option 1 – high performance glass | ||
| Element cost (£) | cost/m2 gfa (£) | |
| Construction cost of base scheme | £58,297,700 | £1,777.39 |
| Roof | 29,900 | 0.91 |
| Extra over double-glazed roof glazing for improved thermal/solar performance; high performance glass; toughened and heat strengthened | 110 m2 @ £70 | |
| Extra for; enhanced insulation to roof slabs to meet new U-values (overall thickness 150 mm) | 2770 m2 @ £8 | |
| External walls, windows and doors | 2,529,400 | 77.12 |
| Extra over double glazed curtain walling; for improved thermal/solar performance; triple wall facade with interstitial blinds | 12,500 m2 @ £200 | |
| Extra over soffit panels and louvres for improved insulation to meet revised U-value (encased insulation, overall thickness 130 mm) | 980 m2 @ £30 | |
| Furniture and fittings | -90,000 | -2.74 |
| Saving for; blinds now included in the triple facade system | 5000 m2 @ £18 | |
| Heating, air treatment and ventilation | -97,000 | -2.96 |
| Extra for; high efficiency boiler plant; condensing boilers | item @ £30,000 | |
| Saving for; reduced boiler capacity and pipework sizes due to improved facade performance; reduction of 100 kW; reduction related to perimeter heat losses only | item @ -£24,000 | |
| Saving for; reduced chiller capacity and pipework sizes due to improved facade performance; reduction of 950 kW; reduction related to solar heat gains only | item @ -£170,000 | |
| Extra for; allowance for heat recovery installation to air handling plant | item @ £12,000 | |
| Extra for; allowance for 10% increase in ductwork cross section area (including insulation) | item @ £35,000 | |
| Extra for; allowance for variable speed drives to pumps and fans | item @ £20,000 | |
| Special installations | 30,000 | 0.91 |
| Extra for; allowance for enhanced BMS controls; additional programming | item @ £10,000 | |
| Extra for; allowance for additional metering to landlord's plant | item @ £20,000 | |
| Builders’ work in connection | 6000 | 0.18 |
| Extra over costs of additional builders’ work | item @ £6000 | |
| Preliminaries and contingencies | 491,000 | 14.97 |
| Contractor’s overheads, site establishment and supervision; allow 15% | item @ £361,000 | |
| Allowance for provision of log books and enhanced manuals | item @ £10,000 | |
| Contingency sum; allow 5% | item @ £120,000 | |
| Construction cost – building only, including costs of Part L compliance | £61,197,000 | £1865.78 |
| Extra over costs of Part L Compliance | £2,899,300 | £88.39 |
| Overall percentage increase | 4.97% | |
| Business Park scheme | ||
| Enhancements to scheme to comply with Approved Document L2 | ||
| Option 2 – low-emissivity glass | ||
| Element cost (£) | cost/m2 gfa (£) | |
| Construction cost of base scheme | £2,882,100 | £793.97 |
| Substructure | 7200 | 1.98 |
| Extra for: enhanced insulation to edges of ground floor slab to meet new U-values; 50 mm thick | 240 m @ £30 | |
| Roof | 38,500 | 10.61 |
| Extra for; additional insulation to pitched roof; between and across rafters; 150 mm thick | 1745 m2 @ £18 | |
| Extra for; additional insulation to flat roof; 150 mm thick | 890 m2 @ £8 | |
| External walls, windows and doors | 21,400 | 5.90 |
| Extra for; enhanced insulation to cavity wall construction; 150 mm thick; including works below DPC | 1070 m2 @ £1 | |
| Extra over for low-e glazing to windows and doors | 855 m2 @ £12 | |
| Extra for; enhanced insulation to plant room louvre panels and cladding; (encased insulation, overall thickness 130 mm) | 335 m2 @ £30 | |
| Furniture and fittings | 15,400 | 4.24 |
| Window blinds | 855 m2 @ £18 | |
| Heating, air treatment and ventilation | 1600 | 0.44 |
| Saving for; reduced boiler capacity due to improved thermal performance of building fabric; reduction of 15 kW; reduction related to perimeter heat losses only | item @ £3600 | |
| Extra for; allowance for variable speed drives to boiler pumps | item @ £2000 | |
| Special installations | 5000 | 1.38 |
| Extra for; allowance for energy metering to main plant and distribution boards | item @ £5000 | |
| Builders’ work in connection | 400 | 0.11 |
| Extra over costs of additional builders’ work | item @ £400 | |
| Preliminaries and contingencies | 19,700 | 5.43 |
| Contractor’s overheads, site establishment and site supervision; allow 12% | item @ £10,400 | |
| Allowance for provision of log books and enhanced manuals | item @ £5000 | |
| Contingency sum; allow 5% | item @ £4300 | |
| Construction cost – building only, including costs of Part L compliance | £2,988,100 | £823.18 |
| Extra over costs of Part L compliance | £106,000 | £29.21 |
| Overall percentage increase | 3.55% | |
| City Office scheme | ||
| Enhancements to scheme to comply with Approved Document L2 | ||
| Option 2 – double-glazed curtain walling with high performance glass and blinds | ||
| Element cost (£) | cost/m2 gfa (£) | |
| Construction cost of base scheme | £58,297,700 | £1,777.39 |
| Roof | 35,400 | 1.08 |
| Extra over double glazed roof glazing for improved thermal/solar performance; high performance glass; toughened and heat strengthened | 110 m2 @ £70 | |
| Extra for; enhanced insulation to roof slabs to meet new U-values (overall thickness 150 mm) | 2770 m2 @ £10 | |
| External walls, windows and doors | 654,400 | 19.95 |
| Extra over double glazed curtain walling; for improved thermal/solar performance; high performance glass; clear super neutral to outer leaf | 12,500 m2 @ £50 | |
| Extra over soffit panels and louvres for improved insulation to meet revised U-value (encased insulation, overall thickness 130 mm) | 980m2 @ £30 | |
| Heating, air treatment and ventilation | 68,000 | (2.07) |
| Extra for; high efficiency boiler plant | item @ £30,000 | |
| Saving for; reduced boiler capacity and pipework sizes due to improved façade performance; reduction of 62 kW; reduction related to perimeter heat losses only | item @ (£15,000) | |
| Saving for; reduced chiller capacity and pipework sizes due to improved façade performance; reduction of 840 kW; reduction related to solar heat gains only | item @ (£150,000) | |
| Extra for; allowance for heat recovery installation to air handling plant | item @ £12,000 | |
| Extra for; allowance for 10% increase in ductwork cross section area (including insulation) | item @ £35,000 | |
| Extra for; allowance for variable speed drives to pumps and fans | item @ £20,000 | |
| Special installations | 30,000 | 0.91 |
| Extra for; allowance for enhanced BMS controls; additional programming | item @ £10,000 | |
| Extra for; allowance for additional metering to landlord's plant | item @ £20,000 | |
| Builders’ work in connection | 6000 | 0.18 |
| Extra over costs of additional builders’ work | item @ £6000 | |
| Preliminaries and contingencies | 142,000 | 4.33 |
| Contractor’s overheads, site establishment and site supervision; allow 15% | item @ £99,000 | |
| Allowance for provision of log books and enhanced manuals | item @ £10,000 | |
| Contingency sum; allow 5% | item @ £33,000 | |
| Construction cost – building only including costs of Part L compliance | £59,097,500 | £1801.77 |
| Extra over costs of Part L compliance | £799,800 | £24.38 |
| Overall percentage increase | 1.37% | |