In this engineering services cost model, the Cost Research and Engineering Services Departments of Davis Langdon & Everest examine the capital cost of services installations in apartment buildings. The model examines in detail the mechanical and electrical services costs of a 165 apartment scheme targeted at the top end of the market. The project, with apartments fitted out by the developer, features comfort cooling, all electric heating and hot water systems, together with high quality lighting in kitchens and bathrooms.
Background to the model

Demand for high quality apartments has become a significant component of the housing market in UK city centres. Despite a reduction in demand from overseas investors, interest in property in good locations remains high.

Limitations on the availability of sites, and an increasing requirement for developer contributions towards the cost of affordable housing, are making residential development more complex and costly.

The cost of large-scale schemes varies widely. Although sales price is determined mostly by location, specification must also be tailored to meet market needs.

The selection of an appropriate building services strategy has a significant effect on initial capital costs, development efficiency and the end value. The criteria used to identify an appropriate services strategy include:

  • comfort and marketing issues;

  • initial capital costs;

  • requirements for plantroom, riser and horizontal distribution space;

  • ease of services distribution and buildability.

    The selection of systems on residential projects is usually determined by the priorities of the developer which is to optimise development efficiency, capital cost and buildability. As a result, many projects feature all-electric solutions for heating and hot water supply. Long-term issues related to running costs and sustainability are not often considered to be high priority on residential projects.

    Table 1 summarises the capital cost and plant and riser space requirements of a range of mechanical services design options for space heating, hot water supply and kitchen/bathroom extract.

    Localised all-electric heating and hot water systems have clear benefits for the developer in terms of initial cost and space utilisation. However disadvantages include poor energy efficiency, limits on local storage capacity and the necessity for separate installations to supply landlords' areas. There is little evidence that the specification of all-electric systems affects the development value of these schemes.

    The higher capital cost and plant space requirements associated with centralised lthw systems can be offset by greater energy efficiency, lower running costs and the popularity of wet radiator systems with occupiers.

    The calculation of the capacity of centralised systems is complicated by the need to acccomodate a wide potential variation in demand related to levels of occupancy. A more complex and expensive metering system is also required.

    PROJECT DETAILS

    Cost datum 2nd quarter 1999

    Location Inner London

    Gross internal floor area (GIFA) 22 750 m2

    Residential area (RA) 14 150 m2

    Procurement route Fixed price lump sum contract using a competitive two-stage tender process

    Project contract period 18 months

    Contract value £28 000 000

    Services contract value £7 000 000

    MAIN DESIGN PARAMETERS

    External design temperatures
    Winter 4°C (saturated)
    Summer 29°C db/20°C wb

    Internal design temperatures
    Heating
    Apartments 21°C±2°C
    Staircases 18°C±2°C
    Cooling
    Apartments 22°C±2°C

    Car park ventilation
    Natural infiltration 1·5 ac/h

    Mechanical ventilation
    Bathroom extract 15 litres/s/room
    Kitchen extract 60 litres/s/room

    Cooling loads
    Lighting 15W/m2

    Lighting
    Lobbies 200 lux
    Entrance hall 250 lux

    PUBLIC HEALTH INSTALLATION

    Sanitary fittings WC suites, wash basins, baths, showers and kitchen sinks to 165 nr apartments (based on two bathrooms per apartment)
    £21.75/m2 GIFA
    £34.97/m2 RA

    Water installation Cold water service, incoming mains, booster pumpset, boosted cold water mains risers, including trace heating and insulation
    £6.60/m2 GIFA
    £10.61/m2RA

    Hot and cold water distribution in apartments
    £16.50/m2 GIFA
    £26.53/m2 RA

    Extra for electric water heating with local hot water storage heaters in apartments
    £5.80/m2 GIFA
    £9.33/m2 RA

    Disposal – rainwater Cast iron internal stacks and horizontal high level distribution, above ground
    £4.50/m2 GIFA
    £7.23/m2 RA

    Disposal – soil, waste and ventilation Cast iron internal stacks
    £6.30/m2 GIFA
    £10.13/m2 RA

    PVC and muPVC branches and connections
    £6.55/m2 GIFA
    £10.53/m2 RA

    Allowance for drainage to fire-fighting lift lobbies
    £0.65/m2 GIFA
    £1.05/m2 RA

    Extra for safety discharge stacks, branches and connections to hot water heaters in apartments
    £3.50/m2 GIFA
    £5.63/m2 RA

    Disposal installation – condensate Horizontal and vertical pipework, branches and fittings in copper
    £4.00/m2 GIFA
    £6.43/m2 RA

    Public health total
    £76.15/m2 GIFA
    £122.44/m2 RA

    MECHANICAL SERVICES INSTALLATION

    Chilled water installation Air-cooled packaged chiller plant, approx 700 kW duty, pipework distribution in plantrooms and to apartments, pumps, pressurisation unit, water treatment, insulation
    £21.00/m2 GIFA
    £33.76/m2 RA

    Chilled water distribution within apartments, insulation
    £10.90/m2 GIFA
    £17.52/m2 RA

    Toilet extract ventilation Local extract fans, ductwork, attenuation, discharge louvres to building facade, controls
    £8.05/m2 GIFA
    £12.94/m2 RA

    Kitchen extract ventilation Local extract fans, ductwork, attenuation, discharge louvres to building facade, controls
    £5.45/m2 GIFA
    £8.76/m2 RA

    Lift motor room and refuse store ventilation Allowance for ductwork and extract fans
    £2.20/m2 GIFA
    £3.54/m2 RA

    Comfort cooling Two-pipe fan coil units with waterside control, chassis type units;architectural casings by others, to all habitable rooms
    £18.15/m2 GIFA
    £29.18/m2 RA

    Heating Perimeter heating to apartments,finned convectors
    £9.35/m2 GIFA
    £15.03/m2 RA

    Extra for electric heating coils to fan coil units
    £0.15/m2 GIFA
    £0.24/m2m RA

    Electric heating to landlord's areas
    £1.50/m2 GIFA
    £2.41/m2 RA

    Building management system Centralised bems/controls installation comprising motor control centres, isolators, starters and all controls, outstations and monitoring; including allowance for controls, timeclocks and individual metering within apartments
    £30.75/m2 GIFA
    £49.44/m2 RA

    Dry riser Dry riser, landing valves and breaching inlets
    £2.00/m2 GIFA
    £3.22/m2 RA

    Testing and commissioning Testing and commissioning of mechanical and public health installations including operating and maintenance manuals and record drawings
    £1.30/m2 GIFA
    £2.09/m2 RA

    Mechanical services total
    £110.80/m2 GIFA
    £178.13/m2 RA

    ELECTRICAL SERVICES INSTALLATION

    Sub-mains distribution LV switchgear and cabling; distribution boards and sub-mains cable distribution; rising busbars and cabling
    £14.50/m2 GIFA
    £23.31/m2 RA

    Power supply to central plant
    £1.30/m2 GIFA
    £2.09/m2 RA

    Small power Small power to public areas, circulation and plantrooms
    £1.50/m2 GIFA
    £2.41/m2 RA

    Small power to apartments and high quality accessories
    £1.50/m2 GIFA
    £2.41/m2 RA

    Trace heating to car park ramp
    £0.40/m2 GIFA
    £0.64/m2 RA

    Fire alarm Addressable fire alarm to BS 5839, detectors and call points to public areas, car parks and plantrooms, control panel
    £5.00/m2 GIFA
    £8.04/m2 RA

    Fire alarm to BS 5839, mains powered smoke alarms to apartments
    £0.75/m2 GIFA
    £1.21/m2 RA

    Lighting Lighting installation to public areas
    £10.30/m2 GIFA
    £16.56/m2 RA

    Lighting installation to car park, plantrooms and refuse areas
    £5.70/m2 GIFA
    £9.16/m2 RA

    Lighting installation to apartments; high quality fittings
    £31.10/m2 GIFA
    £50.00/m2 RA

    External and feature lighting
    £2.00/m2 GIFA
    £3.22/m2 RA

    CCTV installation CCTV system covering entrances, lift lobbies and car park
    £12.00/m2 GIFA
    £19.29/m2 RA

    Communications TV and FM aerial installation
    £7.05/m2 GIFA
    £11.33/m2 RA

    Telephone cabling and containment
    £3.95/m2 GIFA
    £6.35/m2 RA

    Security Video entryphone security system, intruder detection and door access control
    £12.00/m2 GIFA
    £19.29/m2 RA

    Earthing and bonding
    £1.30/m2 GIFA
    £2.09/m2 RA

    Lightning protection
    £0.50/m2 GIFA
    £0.80/m2 RA

    Electrical services total
    £124.75/m2 GIFA
    £200.56/m RA

    Services installation total
    £311.70/m2 GIFA
    £501.13/m2 RA

    EXCULSIONS

    • Builders' work in connection with services installations;

    • Inflation beyond 2nd quarter 1999;

    • External works, including statutory authority connection charges;

    • HV substation;

    • Main contractor's preliminaries, overheads and profit and attendances;

    • Professional and prescribed fees;

    • Contingencies and design reserve;

    • Below slab drainage;

    • Handheld fire-fighting equipment;

    • Tax allowances;

    • Value Added Tax.

    • Source

    Building Sustainable Design

    Related files/tables