• by Kevin Murphy

London: The Glass Building Dilemma

The construction of new tall buildings with glass facades for London never seems to end but should these particular projects be allowed at all? The most obvious example is the 90+storey The Shard just a few minutes from the the London Bridge Tube station is one type of tall building being scrutinised because of its use of all-glass according to a report by Archinect.

Simon Sturgis, an adviser to the government and the Greater London Authority, as well as chairman of the Royal Institute of British Architects sustainability group was quoted in the Guardian this past July:

“If you’re building a greenhouse in a climate emergency, it’s a pretty odd thing to do to say the least.”

“If you’re using standard glass facades you need a lot of energy to cool them down, and using a lot of energy equates to a lot of carbon emissions.”

With climate change and the effects on communities some cities are looking to ban all-glass skyscrapers for future developments because of the high energy demands they require. The use of double and triple-glazing glass facades is now being reviewed because of questions of their limited lifespan for energy efficiency.

Mr. Sturgis:

“To mitigate the amount of energy used to cool these buildings, you have to produce a really complicated façade, which is usually triple glazed.”

“But double glazed units and laminated glass don’t last very long – 40 years or so. So you have to replace your facade every 40 years."

But this scrutiny of sorts is really nothing new. As far back as 2014 the BBC reported that the developers and designers of the Gherkin skyscraper had changed their opinions on the construction of glass buildings. The architect Ken Shuttleworth of the developer Foster and Partners calls the building a 'mistake'.

"The Gherkin is a fantastic building,"

"But we can't have that anymore. We can't have those all-glass buildings. We need to be much more responsible."

The BBC report found that the Gherkin may have been the catalyst for the construction of some of Londons mot well known and odd looking buildings citing the city landmarks known as the Leadenhall Building referred to as the Cheesegrater and the 20 Finchurch Street building known as the Walkie Talkie.

The 20 Finchurch Street building was accused of melting cars because of its glass facade and the suns rays beaming down on streets. A 'brise soleil' or sunshade for the building was applied for to local planners by the developer Land Securities.

Shuttleworth who is no longer with Foster and Partners is now leading the charge in ceasing the construction of the glass buildings told the BBC:

"Everything I've done for the last 40 years I'm rethinking now."

"If you were designing [the Gherkin] today... it wouldn't be the same product all the way around the building."

"We need to be much more responsible in terms of the way we shade our buildings and the way we thermally think about our buildings."

The problem with glass is the amount of heat that collects with glass and is let out of the structure and now governments are calling for better standards in dealing with 'solar gain' or the amount a building absorbs in sunlight and heats up.

New construction measures are being developed with Land Securities developing the structure called the Zig Zag in London SW 1 with the building designed to keep itself cool.

But there are those who question the latest trends to diminish glass structures. One of those is engineer Andrea Charlson of the team at the firm Arup that is researching new ways to increase material sustainability. Speaking to the BBC:

"There have been a lot of advancements in glass technology in the last few years and it's amazing what we can do now in terms of putting coatings on glass. Some of them can be a heavy colour tint that will provide some shading. Others will be almost invisible but will still keep a lot of the heat and solar gain outside a building,"

"As the glass technology improves, one of the biggest causes of heat loss is through the framing. The heat energy will always try to find the path of least resistance."

Also voicing concerns has been the trade association Glass For Europe which stated in 2014:

"A whole palette of glass products is available for the glazing to meet different functions in the building envelope."

"Glass is fit for all climates."

Last week in a report in The Guardian a study revealed that:

"...electricity use per square metre of floor area was nearly two and a half times greater in high-rise office buildings (20 or more storeys) than in low-rises (six storeys or less)."

"Glass skyscrapers are the worst offenders. Large windows may provide magnificent views but they leak heat in cold weather; even triple glazed windows lose far more heat than a well-insulated brick wall."

Also effecting temperatures are not only the presence of heat from the glass widows but people and electronic equipment in offices.

As for hot summer months the report found:

'...carbon emissions from air-conditioned offices are about 60% higher than offices with natural or mechanical ventilation."

The popularity and use of the air conditioning is expected to triple by 2050 thus making renewable energy for the demand will require a new and radical approach to multiple occupancy office designs.

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