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Base building, single-storey primary school
Basic information
Gross internal floor area3912 m2
ConstructionSteel frame of 37 kg/m2
Substructure200 mm ground-bearing slab
RoofPitched, aluminium standing seam
External walls103 mm brick-faced cavity wall
Window framesAluminium
Windows Double-glazed, low-emissivity glass
Capital costs (£)
Substructure574,262
Structure279,893
External envelope1,167,584
Internal divisions329,444
Fininshings and fittings941,967
Mechanical 493,971
Electrics and communications574,573
Builders’ work22,005
Preliminaries837,848
Total5,221,548
Net present costs for key components (£)
Space heating4,276
Fans203
Other energy costs7,478
Total (over 30-year period)11,957
Replacement and maintenance costs per year (£)
Roof5,993
Rooflights2,814
Roof drainage: gutters7,850
Rainwater downpipes5,339
External walls54,337
Windows18,775
External doors3,402
Redecoration44,286
Window blinds26,343
Heat source47,930
Light fittings20,018
Total 237,088
Energy cost changes for increased ceiling height and more glazing
ÌýÌýCost/yr £Percentage change
Fabric heat lossesÌý18710.3%
Ventilation lossesMechanical vent9611.1%
ÌýInfiltration and leakage353.5%
Solar gainsÌý-7526.4%
Heat gains from lightsÌý8-4.8%
FansÌý2512.3%
LightingÌý-81-4.6%
TOTAL CHANGE PER YEARÌý1952.0%
SPACE HEATING
COOLING
OTHER ENERGYÌý
Scenario 1: An increase in ceiling height and glazing – repair and maintenance costs
The graph right shows an increase in net present cost of £24,100. The slight reduction on light fittings assumes that the lamp life reduces slightly as the lights will be switched on less often.
Over 30 years, the combined effect for a change of increase in the ceiling height, mainly for high-level glazing, are:
Capital cost changes +£140,000
Energy cost changes +£3,500
Maintenance and replacement changes +£24,100
Total change in net present cost +£167,600
Energy cost changes for going from one to two storeys
ÌýÌýCost/yr £Percentage change
Fabric heat lossesÌý-473-23.6%
Ventilation lossesMechanical vent60.7%
ÌýInfiltration and leakage-342-29.9%
Solar gainsÌý-124.4%
Heat gains from lightsÌý-21.2%
FansÌý21.0%
LiftsÌý39NA
General powerÌý160.6%
LightingÌý251.4%
TOTAL CHANGE PER YEARÌý-741-6.2%
SPACE HEATING
COOLING
OTHER ENERGY
Scenario 2: Adding another floor and reducing footprint – repair and maintenance costs
The combined effect for a change from single to two-storey construction:
Capital cost changes–£118,000
Energy cost changes –£13,500
Maintenance and replacement changes+£5,500
Total change in net present cost–£126,000
The main economic advantage of using two storeys rather than one, is not normally construction costs, but the conservation of land.