Lifetime costs: environmental control | Features

Lifetime costs
	Capital cost £/m2	Energy cost £/m2	Maintenance cost £/m2	Net present value £/m2 (60-year life)	Service life (years)
Centralised air system
Ventilation and heating (no air-conditioning)	100	1.9	1.5	190	20
Constant volume (single zone)	160	3	1.5	286	25
Variable air volume	180	2.4	2.5	320	20
Dual duct	210	3.4	1.5	361	20
Partially centralised air/water system
Centralised air with re-heat	200	3.1	2.5	336	25
Unitary heat pumps	130	3.2	2.5	314	12
Fan coil units	170	3.2	3	360	15
Local systems
Heat and local ventilation (no air-conditioning)	90	1.1	0.8	141	25
Split package units	85	3.5	2.5	225	15
Variable refrigerant flow rate	130	2.8	2.5	284	15
Costs are based on £/m2 of treated floor area (gross areas less plant rooms and other non-heated areas).
Capital costs include supply and installation and the removal and replacement at the end of its service life.
Replacement costs are 80% of original supply and installation cost.
Maintenance and component replacement include: ductwork inspection and cleaning; filter replacement; cleaning fan coil units; maintenance of heating and cooling plant and controls to Heating and Ventilation Contractors’ Association standard maintenance specification.
Costs are discounted to net present values at a discount rate of 6%.
Energy and maintenance costs are annual figures.