A call to ban glass tower blocks in New York City, proposed by their Mayor Bill de Blasio, has brought calls to adopt the same measure in London.
Mr De Blasio said that buildings were the biggest cause of greenhouse gas emissions in New York and he is most probably right. Buildings are certainly the biggest contributors of CO2 emissions in the UK.
The pledge by the New York Mayor is to pass laws prohibiting the construction of heavily glazed towers with the objective to reduce carbon emissions and to ensure that developers take stringent measures so buildings are part of the solution, not part of the problem.
In response to an article in the Architects Journal, Simon Sturgis of consultancy Targeting Zero Carbon suggested that London should follow suit citing two key reasons. The first being huge amounts of heat absorbed by glass buildings that requires high levels of cooling energy to remove it and the second being its life cycle issue.
On the other hand, other contributors highlight that buildings with double-skin façades such as the Shard, Heron Tower and 22 Bishopsgate use effective shading within the façade that reduces the solar gain and as such the need for cooling energy and additionally minimises heat loss in winter. Further comments propose the use of photovoltaic and bio-diversity technologies.
The reality though is that England has a ban on glass skyscrapers due to latest changes to Part B of the Building Regulations. The Shard, for example, could no longer be built.
Since December 2018 combustible materials on external walls are banned. Whilst glass and frames are exempt, MCHLG have confirmed that attachments within the façade or affixed to it are not and this includes blinds, PV and other technologies. So quite simply, tall highly glazed buildings with any residential element are no longer possible due to these latest changes. We are not sure where this leaves building designers trying to meet Part L and TM59.
The British Blind & Shutter Association (BBSA) has challenged the banning of shading in Part B and is seeking a judicial review on several points but principally that the basis of the outcome is misconceived as it focusses on combustibility rather than flammability. It is impossible to manufacture a dynamic shading product to the required combustibility requirement in the revised Part B.
Dynamic shading incorporated within the glass façade is a recognised, proven and safe solution to overheating in highly glazed buildings.
The BBSA fully understands and supports the need to prevent flame spread and can confirm that, based on initial testing, our members’ products will not contribute to the problem of flame spread. Further full-scale testing is currently underway to confirm this.
And just to be certain, it is the need to reduce greenhouse gas emissions and the need for cooling in buildings that lead to Bill de Blasio’s pledge. In the UK in the ten years since 2006 overall electricity consumption has fallen by 15.2% and that of natural gas by 32.8% (figures from BEIS). However, a Building Research Establishment report has confirmed that the electricity used for air-conditioning had been underestimated by some 45% at 20TWh, whereas in reality this was 29TWh. To put that in perspective, the 9TWh difference is around the expected output of Hinkley Point C.
Banning dynamic shading products that are crucial enablers of buildings with large areas of glazing by helping to achieve the all-important energy balance of buildings is not a solution to the climate change problems we all face.
Unless the building regulations are changed the de facto ban on glass skyscrapers will carry on.
