Green Sky Thinking: Squire and Partners' 5 Hanover Square
How green is inherently green?
Squire and Partners’ first foray into Green Sky Thinking was a talk boldly entitled, ‘Inherently Green: Sustainability Measures in the Development of 5 Hanover Square’. The design team from Squire and Partners, AECOM, Stanhope and Mace spoke about the sustainability strategy of this BREEAM Excellent project which was presented as an ‘exemplary sustainable city centre building’. The talk was followed by a guided tour of the building and the roof. While the speakers were engaging and confident about the sustainable credentials of the mixed-use development, it was evident that this was not so much an ’exemplary’ green project but rather a demonstration of how the constraints on office design make ‘inherently green’ design in the commercial sector so difficult.
- Michael Squire, Squire and Partners
- James Denner, Squire and Partners
- Brett Wharton, Stanhope
- Matthew Hignell, AECOM
- Guy Hunt, Mace
Michael Squire introduced the project, describing the approach that the design team took: ‘It was about examining things to make sure that they are sensible’ and moving away from what he described as the poor environmental performance of a glass office building towards a more intelligent approach to environmental design. One example he cited was the use of deep white reveals to bring a more diffuse daylight into the workspace. This examination did not extend as far as open-able windows. Squire claimed this was impossible to do in central London due to the noise, an assumption that needs to be questioned if we are to improve the environmental performance of offices.
Brett Wharton spoke about Stanhope’s approach to sustainable design, explaining that sustainability was an intrinsic part of their business and that they liked to take a wide view on the subject. The Hanover Square site is close to key transport infrastructure including a future Crossrail link. Wharton spoke about how Stanhope’s sustainability framework informed their decisions and that this included appropriate site selection and design for longevity. He talked about BREEAM and the Code for Sustainable Homes Level 4 as being badges and that when appropriate Stanhope take the criteria further.
James Denner of Squire and Partners presented the BREEAM scores of the project and explained that the renewable energy strategy was limited to photovoltaics on the roof when a thorough analysis showed that wind turbines would contribute a negligible amount of energy to the scheme.
Matthew Hignell of AECOM continued to describe the technical aspects of the building services. He explained that the building location was not appropriate for a biomass-boiler and that the energy profile made it unsuitable for combined heat and power. Other green features were the development of an efficient chiller for the air conditioning and a lighting load that is only 8W/m2. A green wall was included in the project to increase the biodiversity of the area. The lack of discussion of alternatives to mechanical ventilation was notable and contributed to a sense that this project was focussed on achieving best practice rather than being really pioneering.
Guy Hunt spoke about the role of the contractor, MACE. He explained that they took various steps to reduce the amount of material in the building as this reduced the carbon impact of the fabric and the construction process. He claimed that the use of a post-tensioned slab reduced the amount of concrete by 768 tonnes which is 96 trucks worth. It also reduced the amount of steel reinforcement by 250 tonnes. The carbon impact of the concrete was also improved by replacing 20 per cent of the cement with GGBS and reusing onsite waste as aggregate. In addition, 97 per cent of waste was reused or recycled on site.
The Q&A was revealing. There was a consensus among the design team that BREEAM was a good starting point but that a truly sustainable project required going further and understanding the building in ‘the round’. Of particular interest was the architect’s response to a question about the daylight factors in the building: 5 Hanover Square is a deep-plan building and it is challenging to achieve decent daylight factors in a central London project.
This talk was as interesting for what was not said as for what was. There is no doubt that the design team was diligent in attempting to mitigate the environmental impact of this building. However the outcome is a building that is difficult to describe as ‘inherently green’. There was no mention of an attempt to create a naturally-ventilated (like UCL’s School of Slavonic and Eastern European studies or Commerzbank’s headquarters in Frankfurt.) or better daylight levels challenging the current assumptions in office design. 5 Hanover Square, while exemplary within the constraints of the market, is proof of just how restrictive current expectations surrounding office design are.