This case study highlights the importance of collaboration between the façade and building services to enhance the whole life carbon of a high-rise building in central London. The challenge has been to optimise a complex building façade without compromising its aesthetic appearance which was already discussed with the Planning Authority.
With focus on sustainability and decarbonisation, the team adopted an iterative collaborative approach to review and implement the façade design, aiming to find a good balance between the embodied and operational carbon, while meeting the stringent performance requirements.
The Façade team reviewed the design at different scales, i.e., geometry, system, and detailing, identifying optimised design alternatives and opportunities for embodied carbon reduction. The Services team evaluated each of the proposed designs, updating the energy model to reflect the corresponding operational carbon benefits.
The proposed optimised design comprises a CCF with double-glazed units and is characterised by a reduced window-to-wall ratio compared to the baseline. The optimisation opportunities identified by the team are related to the buildability, thermal performance, and embodied carbon. The proposed rationalised geometry has resulted in 50% reduction of the façade types, 12% reduction of façade surface area, and ease of construction and installation.
To meet the stringent thermal performance targets, triple glazing would be required, however, to mitigate the impact on embodied carbon due to heavy glazing, opaque areas combined with double-glazing were proposed to meet the desired performance. On a detailed level, components with low carbon, such as composite or post-consumer recycled aluminium frames, showed a potential further 20% reduction in embodied carbon. All these measures have brought a potential saving in CO2 emissions equivalent to a forest as large as 1.5 times Central Park in New York.
Key lessons learned
- Early-stage collaboration is vital to prevent underestimating the design performance and ensure a buildable, efficient façade with optimised whole life carbon and operational performance
- Early-stage carbon assessments are critical to evaluate the various façade systems and their benefits/impact on the whole life carbon
- Fully glazed façades present challenges in decarbonisation strategies due to the need for additional solar control measures, which increase the embodied carbon