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Comparison of services design criteria: offices and call centres
Design criteria   Specification standard
British Council for Offices
(best practice in the specification for offices)		 Call centre floor
(typical specification)
Occupational density indoor
climate control (person/m2)		   1:14 1:5-1:8
WC provision
(gender split/person/m2)		   60/60 @ 1:14 70/60 @ 1:8
Fresh air ventilation
(litres/sec/person)		   8-12 12
Cooling loads – small power (W/m2) 15 up to 60+
  – lighting (W/m2) 12 15
Primary power – equipment (W/m2) 15-25 up to 70+
  – lighting (W/m2) 12 15
Lighting – office areas (lux) 350-400 350-400
Cost breakdown
element
cost £		 £/³¾2
gifa		 % of
total cost
Substructure 390 000 49.37 4.42
Ground slab; 200 mm thick reinforced insitu concrete bed, hardcore;
damp-proof membrane; reinforced concrete column bases		 6500 m2 @ £55
Allowance for below-ground drainage and incoming services 6500 m2 @ £5
Frame 517 100 65.46 5.87
Structural steel framing; 30 m clear span; allowance based on 50 kg/m2 (average rate for universal and hollow sections) 325 t @ £1,200
Allowance for structural steelwork to mezzanine based on 35 kg/m2 50 t @ £1,050
Cold-rolled galvanised steel roof purlins; 1.6 m centres; 4.5 kg/m2 average weight 5500 m @ £6
Fire protection ; rigid board fire protection; one-hour fire resistance to columns 700 m2 @ £20
Fire protection; intumescent paint; one-hour fire resistance to exposed roof structure 1200 m2 @ £23
Upper Floors 100 500 12.72 1.14
Prestressed, precast concrete structural suspended floor units; 50 mm thick structural topping 1400 m2 @ £70
Extra for 7.5 kN/m2 floor loading to plant room areas 500 m2 @ £5
Roof 424 000 53.67 4.81
Roof cladding; curved; raised-seam aluminium roofing; cladding; structural deck; insulation; vapour barrier; soffit lining 6800 m2 @ £40
Extra for rooflights; double-skin polycarbonate; including framing and secondary steelwork; sunshading 200 m2 @ £260
Allowance for automatic smoke vents to stairwells item @ £4,000
Allowance for work to boundaries, gutters, rooflights, openings and so on 1050 m @ £20
Entrance canopy; hollow-section framing; structural glazing; complete item @ £30 000
Allowance for roof safety system 500 m @ £90
Stairs 43 000 5.44 0.49
Precast concrete stairs and half landings; overall rise 4 m; stainless steel handrails; finishes 1 @ £10 000
Precast concrete stairs and half landings; overall rise 4 m; polyester-powder-coated steel handrails; finishes 1 @ £8,000
Allowance for access platforms and stairs to plant rooms item @ £20 000
Allowance for roof access, stairs and hatches item @ £5,000
External walls, windows and doors 721 500 91.33 8.18
Curtain walling; framed double-glazed units; colour coated aluminium framing; flashings; accessories 660 m2 @ £250
Wall cladding; colour-coated aluminium; smooth-faced composite panels; flashings; accessories 2025 m2 @ £200
Extra for aluminium-framed, thermally broken window units; sealed double-glazed units; 30% opening lights 200 m2 @ £100
Extra for glazed entrance screen; two fully glazed double doorsets; ironmongery and accessories 50 m2 @ £300
Extra for louvre panels to plant areas; colour coated 200 m2 @ £100
Sunshading to windows and curtain walling 250 m @ £250
High-security steel double doors and frames; colour coated; ironmongery; accessories 16 @ £2,000
Sectional doors to loading bay; electrically operated; 2.4 × 2.7 m; including controls 7 m2 @ £280
Internal walls and partitions 351 800 44.53 3.99
Insitu concrete shear walls; average 215 mm thick 200 m2 @ £75
Blockwork partitions; 215 mm average thickness, 140 mm blocks laid on side; head restraint 1300 m2 @ £38
Metal stud partitions; two layers wallboard, each side; insulation 3100 m2 @ £35
Demountable partitions; monobloc with fully glazed office fronts; including doors, ironmongery and accessories 1350 m2 @ £110
WC cubicle partitions 40 @ £600
Melamine-faced solid laminate access panelling to WCs and so on 80 @ £80
 
Cost breakdown
element
cost £		 £/³¾2
gifa		 % of
total cost
Internal doors 104 000 13.16 1.18
Flush doors; fire-rated; solid-core veneer-faced; hardwood frames; ironmongery; complete 55 @ £650
Flush doors; non-fire-rated; solid-core veneer-faced; hardwood frames; ironmongery; complete 115 @ £550
Allowance for services access panels item @ £5,000
Wall finishes 114 400 14.48 1.30
Independent wall lining; plasterboard lining to inner face of external walls; two coats emulsion paint 2500 m2 @ £14
Drylining; plasterboard to internal masonry walls; two coats emulsion paint 1500 m2 @ £9
Two coats emulsion paint; to plasterboard partitions 4050 m2 @ £3
Ceramic tiles; sand cement backing to plasterboard 460 m2 @ £40
Vinyl wall finish to plasterboard 1100 m2 @ £8
Extra for enhanced quality applied finishes in rest areas 260 m2 @ £12
Two coats emulsion paint/dust sealer to blockwork 1300 m2 @ £3
Hygienic finishes to kitchen areas; laminate panels 325 m2 @ £60
Floor finishes 525 000 66.46 5.96
Natural stone flooring, including allowances for screeds and skirtings to reception area 50 m2 @ £100
Allowance for mats and matwells item @ £5,000
Raised access floor; 500 mm deep floor void; including allowances
for cavity barriers 		6650 m2 @ £42
Extra for seals to form airtight plenum, for forming holes in floor tiles and for fixing free issue supply air diffusers 6500 m2 @ £4
Heavy-duty carpet tiles; including allowance for cutting holes for floor diffusers and skirtings to raised floor tiles 6500 m2 @ £27
Anti-static vinyl floor tiles; bonded to raised floor tiles; including allowances for cutting holes for floor diffusers and skirtings 150 m2 @ £18
Vinyl floor tiles; including allowance for screed and skirtings; to WCs and kitchen areas 400 m2 @ £27
Semi-sprung beech strip flooring; including allowance for skirtings; to aerobics/gym 100 m2 @ £60
Concrete hardener to raised floor plenums and plant rooms 7350 m2 @ £2
Ceiling Finishes 96 800 12.25 1.10
Suspended ceilings; mineral fibre tiles; semi-concealed grid; to office and support areas 3150 m2 @ £26
Extra for moisture-resistant mineral fibre tiles to WCs 250 m2 @ £5
Extra for acoustic tiles to aerobics areas/gym 100 m2 @ £5
Suspended ceilings, hygienic metal tiles to kitchen areas 250 m2 @ £40
Extra for enhanced ceiling finishes to reception, dining and rest areas 315 m2 @ £10
Furniture and fittings 255 600 32.35 2.90
Reception desk and fittings item @ £10 000
Allowance for furniture and fittings to dining areas item @ £50 000
Allowance for fixed equipment to gym/aerobics areas item @ £10 000
Allowance for fittings; lockers, coat racks, shelves and so on item @ £70 000
Statutory and directional signage item @ £10 000
Allowance for decorative features, banners, graphics and so on to call centre areas item @ £100 000
Window blinds 140 m2 @ £40
Sanitary fittings 33 900 4.29 0.38
WCs, urinals, wash-hand basins; generally 105 @ £250
Allowance for fittings for disabled WCs item @ £1,000
Showers; cabinets; trays; fittings 6 @ £1,000
Cleaners’ sinks 3 @ £200
Services equipment 300 000 37.97 3.40
Catering installation complete; kitchen equipment; dishwash installation; servery fit-out item @ £300 000
Disposal installations 59 300 7.51 0.67
Rainwater disposal; cast iron downpipes and fittings 7900 m2 @ £3.50
Waste, soil and vent installation; PVCu pipework and fittings 7900 m2 @ £4
Water installations 45 000 5.70 0.51
Hot and cold-water service; calorifiers; hot and cold-water storage; distribution 150 @ £300
Cost breakdown
element
cost £		 £/³¾2
gifa		 % of
total cost
Space heating and air treatment 1 652 300 209.15 18.74
Gas installation item @ £20 000
Low-temperature hot-water heating; boiler plant (900 kW); stainless steel flues; pumps and valves; distribution within plant rooms; insulation 7900 m2 @ £7.50
Perimeter heating; trench heating installation 7900 m2 @ £12
Chilled water installation; chillers and heat rejection (total load 2300 kW); pressurisation unit; pumps and valves; distribution within plant rooms; insulation and trace heating 7900 m2 @ £80
Supply and extract ventilation; air-handling units; heating, cooling and reheat coils; ductwork in risers and plant rooms 7900 m2 @ £28
Supply and extract ventilation; displacement system; ductwork; supply-only floor diffusers 6500 m2 @ £30
Supplementary cooling; two-pipe fan-coil installation to cellular space;
chilled-water distribution; condensate drainage; fan-coil units;
ductwork; insulation; grilles and diffusers		 2900 m2 @ £90
Dedicated cooling to communications room; including back-up provision item @ £50 000
WC extract installation 7900 m2 @ £5
Kitchen supply and extract installation item @ £40 000
Allowance for smoke extract at roof level 7900 m2 @ £5
Electrical installations 611 500 77.41 6.94
Allowance for heating and ventilating installation; 1 MW transformer; HV switchgear item @ £40 000
Mains and submains installation 7900 m2 @ £20
Small power distribution 7900 m2 @ £8
Extra for enhanced small power to call centre floor and training rooms 4000 m2 @ £20
Lighting and luminaires to call centre floor 3700 m2 @ £35
Lighting and luminaires to offices, support space and rest areas 1650 m2 @ £45
Lighting and luminaires to plant rooms 700 m2 @ £10
Emergency lighting installation 7900 m2 @ £5
Power to mechanical services item @ £20 000
Standby generation; small power, lighting and essential services, 2 @ 1500 kVA; providing 100% redundancy; excluded as part of end-user fit-out Excluded    
Uninterruptable-power supply; small power and essential services, 4 @ 500 kVA; providing 100% redundancy; excluded as part of end-user fit out Excluded    
Lift installations 40 000 5.06 0.45
Eight-person, electro-hydraulic lift serving two floors; 0.6 m/s 1 @ £40 000
Protective installations 51 600 6.53 0.59
Lightning protection 7900 m2 @ £2
Earthing and bonding 7900 m2 @ £2
Fire suppression installation to communications room; Inergen item @ £20 000
Communications installations 875 000 110.76 9.92
Fully addressible fire and smoke detection and alarm system 7900 m2 @ £18
Public address system 7900 m2 @ £10
Intruder detection 7900 m2 @ £5
Allowance for security, closed-circuit television and access control 7900 m2 @ £15
Turnstile entry control with card operation item @ £50 000
Wireways for telephones, data and structured cable 7900 m2 @ £5
Structured cabling; providing eight comms ports per work station 6250 m2 @ £65
Special installations 237 000 30.00 2.69
ºÚ¶´ÉçÇø management system 7900 m2 @ £30
Builder’s work in connection 117 000 14.81 1.33
Forming holes, chases and so on, allow 3% item @ £117 000
Preliminaries and contingencies 1 150 000 145.57 13.04
Contractor’s overheads, site establishment and site supervision, allow 10% item @ £767 000
Contingency sum, allow 5% item @ £383 000
     
Total construction cost (building only) 8 816 300 1 115.98 100
Regional variations
Costs in this article are based on a scheme in the Midlands
and should be adjusted by the following location factors
for projects in other areas.
Inner London 1.20
Outer London 1.14
South-east 1.07
South-west 1.03
East Anglia 1.02
Yorkshire and Humberside 1.00
North-west 1.06
North 1.01
Scotland 1.01
Wales 1.00
Northern Ireland 0.86