CIBSE Journal August 2010

Façade engineering Cooling

CIBSE Society of Façade Engineering

In 2003, a group of professionals established the Society of Façade Engineering (SFE) in recognition of the need to ‘regulate’ the industry and introduce a system of accreditation. The SFE was inaugurated in 2004 as a society under CIBSE. The membership is international and the Society

is experiencing significant growth in the regions – notably the Middle East where the SFE was launched in early 2009. There are a number of benefits of SFE membership, including recognised professional status (Associate; Member - MSFE; or Fellow - FSFE); enhanced career opportunities; professional networking; technical events; and magazine. Subscription is free to all existing members of

CIBSE, whereas non-CIBSE members get affiliate CIBSE membership when joining the SFE and get the benefits of CIBSE membership, including free online access to publications. Members are actively encouraged to contribute information to the Elevation magazine of the SFE and take part in the activities coordinated through the SFE Steering Committee. The SFE is supported by the Institution of Structural Engineers and the Royal Institute of British Architects. For more information, visit: wwwacadeengineeringsociety.org

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flat (or flush) façade of similar build-up and layout, (b) the façade from the previous, abandoned scheme, and (c) the double skin façade from the Plantation Place project, representing the state-of-the-art façade (see Figure 5). The performance of the façade was assessed in terms

of the predicted annual energy consumption and the peak loads in the perimeter zone of the building. The modelled depth of the perimeter zone was varied in accordance with the different design scenarios. The effect of the rotation of the windows varies with orientation and scenarios, but the annual energy consumption for cooling is reduced in all cases. In Figures 6 and 7, examples of results are shown for illustration only.

Conclusion The above shows our approach to façade design and the importance of early-stage integration. The commitment of the client and the design team to Ropemaker Place resulted in a scheme with high performance and low environmental impact. The sustainability of the building was demonstrated

through a BREEAM Excellent rating. The property also received LEED Platinum PreQualification for Core&Shell, a first outside of the US. l

Dr Mikkel Kragh is an associate at Arup in Milan, Italy.

20 30 40 50 60 70 80

Cooling load benchmarking studies for different scenarios (illustration only) SBEM standard

Client’s brief 66 69 57 56 48 49 43 28 31 25 21 14

10 0

Flat façade Serrated façade East Flat façade Serrated façade South Flat façade Serrated façade West

Figure 6: Illustrates in principle the effect of the window rotation for three design scenarios. The graph shows the cooling load for a flat façade compared with that of a serrated one. The thermal performance of the serrated façade has been adjusted to allow for both the increased transmission area and the linear losses caused by the comparatively complex geometry

50 47 43 42 34 32 Low energy tenant

Peak load (illustration only) Heating

Cooling

100 120 140

20 40 60 80

0 Base case

Gensler previous scheme

PP1 double-skin façade 200W/m²

PP1 double-skin façade 400W/m²

Annual heating/cooling energy consumption (illustration only) Heating

Cooling

30 40 50 60 70 80 90 100

20 10 0

Current design

Base case

Gensler previous scheme

PP1 double-skin façade 200W/m²

PP1 double-skin façade 400W/m²

Current design

Figure 7: Illustrates in principle the peak loads and annual energy consumption for cooling (blue) and heating (red) and a comparison between different façade configurations. Notably, for the given assumptions, the performance of the serrated façade is comparable to that of a state-of-the-art doubleskin façade system

30 CIBSE Journal August 2010 www.cibsejournal.com

Annual load (kWh/m². year)

Peak load (W/m²)

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