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ItemW/m of facadeG-valueHeightSystem
11000.052.6Passive chilled beams or displacement systems
22000.102.6Active chilled beams
33000.152.6Low-capacity fan coil units or all air system
44000.202.6High-capacity fan coil units but with poorer building energy performance
 DescriptionCost/m²Comments
AUnitised curtain wall, high- performance coated glass sealed units with G-value of 0.25, solid spandrel panels£650/m²Based on table above, this solution will not achieve compliance and will require additional solar control measures
A1Unitised curtain wall, as described in A, but 50% solid panels in addition to spandrel panels£750/m²Should be capable of achieving G-values of 0.15 and 0.20, possibly with less dark high-performance glass, thus cost-effective
A2Unitised curtain wall, high- performance coated glass sealed units with G-value of 0.25, solid spandrel panels£800/m²Should be capable of achieving G-values of 0.15 and 0.20, possibly with less dark high-performance glass, thus cost-effective
A3Unitised curtain wall, as described in A, but with external brise soleil (horizontal blades to south, vertical to east and west)£850/m²Should be capable of accommodating a G-value of 0.10, including high-performance glass
BUnitised curtain wall, as described in A2, but with greater density of brise-soleil for improved solar shading Unitised “externally” ventilated cavity double wall facade, with cavity depth about 100mm. This solution does not require mechanically conditioned air in the cavity. Wider walk-in cavity facades attract a cost premium£1100/m²This option comprises motorised venetian blinds within the cavity, which requires electrical and BMS supply. For a 3.8m storey height and no spandrels, a minimum G-value of 0.10 should be achieved with blinds closed