Costs | Features | Building

Sustainability costs
The following cost analysis by Davis Langdon provides indicative costs for various items of construction that can be incorporated in a building to boost its green credentials. Costs are the national average at first quarter 2004 price levels.
	unit	£
Recycled aggregates
General fill material
Blast furnace slag	t	5.30-8.00
Quarry waste	t	7.00-9.50
Graded material
Crushed concrete	t	5.25-7.50
Brickwork
Extra for lime mortar in lieu of cement mortar	m2	3.50-5.00
Curtain walling
Extra for manually openable windows	each	300-350
Extra for top-hung windows, electrically actuated	each	600-750
Solar shading
Externally mounted aluminium louvres	m2	150-250
External automated fabric blinds, including controls, wind and light sensors	m2	275-325
Rooflights
Extra for fixed rooflight costs for opening vents, tilt and turn, actuator motors	each	750-1000
Roof canopies
To reduce solar heat load and glare	m2	350-500
Ceiling finishes
Self-finished acoustic plaster	m2	20-30
Ventilation
Extract fans, wiring and controls	each	650-750
For a much wider consideration of sustainability issues and costs affecting commercial buildings, refer to Davis Langdon’s Sustainability Cost Model published in Building on 12 September 2003.
Specifiers who do not know the cost of recycled aggregates or solar shading need to buck up their ideas. The government is set to make sustainable specification a condition for building tens of thousands of homes (see Rules, page 17). And architects and designers who still believe that eco-building is just for hippies are in danger of missing out on a green building boom.

Total building energy costs £ per year
Assumptions:	gas cost	83 m2 gifa	electricity cost
	£0.014/kWh		£0.06/kWh
Building type	Heating	Hot water	Electricity	Total
Eco TekHaus	23	35	80	138
Standard TekHaus	42	46	159	248
Building regs 2002	75	58	199	333
Existing Building	267	70	249	586
Note: Omits standing charges.

Total building CO2 emissions kg per year
Assumptions:	80% heating efficiency	107 m2 gifa	0.19 kg CO2/kWh gas	0.44 kg CO2/kWh electric
Building type	Heating	Hot water	Electricity	Total
Eco TekHaus	503	762	753	2019
Standard TekHaus	920	1017	1507	3443
Building regs 2002	1647	1271	1883	4801
Existing building	5845	1525	2354	9724
Notes: kg CO2 figures are for 2000. Source: www.energy-efficiency.gov.uk/document/factfigs/emiss.htm. £ cost figures are from SAP. Assumes some off-peak electricity use.

Heating costs £ per year
Assumptions:	gas cost	107 m2 gifa
	£0.014/kWh
Building type	All out	All in	Half in
Eco TekHaus	15	21	30
Standard TekHaus	29	49	54
Building regs 2002	57	88	97
Existing building	217	322	345

Heating CO2 emissions kg per year
Assumptions:	80% heating efficiency	107 m2 gifa	0.285 kg CO2/kWh gas
Building type	All out	All in	Half in
Eco TekHaus	385	534	755
Standard TekHaus	728	1246	1380
Building regs 2002	1452	2230	2470
Existing building	5527	8196	8767
Further assumptions
Heating energy use has been modelled in detail.
Electrical energy demand and Hot Water Demand is assumed to be reduced through design and specification to the same level as the thermal design in each case.
XCO2 has referred to monitored case studies where possible in making these assumptions.
Assumed 'worst case' scenario of half in occupancy.