Glass skyscrapers are an environment disaster that could have been avoided

3 World Trade Centre, New York City. Image: Getty.

New York Mayor Bill de Blasio has declared that skyscrapers made of glass and steel “have no place in our city or our Earth anymore”. He argued that their energy inefficient design contributes to global warming and insisted that his administration would restrict glassy high-rise developments in the city.

Glass has always been an unlikely material for large buildings, because of how difficult it becomes to control temperature and glare indoors. In fact, the use of fully glazed exteriors only became possible with advances in air conditioning technology and access to cheap and abundant energy, which came about in the mid-20th century. And studies suggest that on average, carbon emissions from air conditioned offices are 60 per cent higher than those from offices with natural or mechanical ventilation.

As part of my research into sustainable architecture, I have examined the use of glass in buildings throughout history. Above all, one thing is clear: if architects had paid more attention to the difficulties of building with glass, the great environmental damage wrought by modern glass skyscrapers could have been avoided.

Heat and glare

The United Nations Secretariat in New York, constructed between 1947 and 1952, was the earliest example of a fully air conditioned tower with a glass curtain wall – followed shortly afterwards by Lever House on Park Avenue. Air conditioning enabled the classic glass skyscraper to become a model for high rise office developments in cities across the world – even hot places such as Dubai and Sydney.

The UN Secretariat building. Image: United Nations Photo/Flickr/creative commons.

Yet as far back as the 19th century, horticulturists in Europe intimately understood how difficult it is to keep the temperature stable inside glass structures – the massive hot houses they built to host their collections. They wanted to maintain the hot environment needed to sustain exotic plants, and devised a large repertoire of technical solutions to do so.

Early central heating systems, which made use of steam or hot water, helped to keep the indoor atmosphere hot and humid. Glass was covered with insulation overnight to keep the warmth in, or used only on the south side together with better insulated walls, to take in and hold heat from the midday sun.

The Crystal Palace

When glass structures were transformed into spaces for human habitation, the new challenge was to keep the interior sufficiently cool. Preventing overheating in glass buildings has proven enormously difficult – even in Britain’s temperate climate. The Crystal Palace in Hyde Park – a temporary pavilion built to house the Great Exhibition of the Works of Industry of All Nations in 1851 – was a case in point.

Painting of Queen Victoria opening the Crystal Palace in London, 1851. Image: Thomas Abel Prior/Wikimedia Commons.

The Crystal Palace was the first large-scale example of a glass structure designed specifically for use by people. It was designed by Joseph Paxton, chief gardener at the Duke of Devonshire’s Chatsworth Estate, drawing on his experience constructing timber-framed glasshouses.

Though recognised as a risky idea at the time, organisers decided to host the exhibition inside a giant glasshouse in the absence of a more practical alternative. Because of its modular construction and prefabricated parts, the Crystal Palace could be put together in under ten months – perfect for the organisers’ tight deadline.

To address concerns about overheating and exposing the exhibits to too much sunlight, Paxton adopted some of the few cooling methods available at the time: shading, natural ventilation and eventually removing some sections of glass altogether. Several hundred large louvres were positioned inside the wall of the building, which had to be adjusted manually by attendants several times a day.

Despite these precautions, overheating became a major issue over the summer of 1851, and was the subject of frequent commentaries in the daily newspapers. An analysis of data recorded inside the Crystal Palace between May and October 1851 shows that the indoor temperature was extremely unstable. The building accentuated – rather than reduced – peak summer temperatures.

A timeline of the temperature in the Crystal Palace, May to October, 1851. Image: Henrik Schoenefeldt/author provided.

These challenges forced the organisers to temporarily remove large sections of glazing. This procedure was repeated several times before parts of the glazing were permanently replaced with canvas curtains, which could be opened and closed depending on how hot the sun was. When the Crystal Palace was re-erected as a popular leisure park on the outskirts of London, these issues persisted – despite changes to the design which were intended to improve ventilation.

Chicago glass

These difficulties did not perturb developers in Chicago from building the first generation of highly glazed office buildings during the 1880s and 1890s. Famous developments by influential architect Ludwig Mies van der Rohe, such as the Crown Hall (1950-56) or the Lakeshore Drive Apartments (1949), were also designed without air conditioning. Instead, these structures relied mainly on natural ventilation and shading to moderate indoor temperatures in summer.

In the Crown Hall, each bay of the glass wall is equipped with iron flaps, which students and staff of the IIT School of Architecture had to manually adjust to create cross-ventilation. Blinds could also be drawn to prevent glare and reduce heat gains. Yet these methods could not achieve modern standards of comfort. This building, and many others with similar features, were eventually retrofitted with air conditioning.

Chicago’s Crown Hall. Image: yusunkwon/Flickr/creative commons.

Yet it’s worth noting that early examples of glass architecture were not intended to provide airtight, climate controlled spaces. Architects had to accept that the indoor temperature would change according to the weather outside, and the people who used the buildings were careful to dress appropriately for the season. In some ways, these environments had more in common with the covered arcades and markets of the Victorian era than the glass skyscrapers of the 21st century.

Becoming climate conscious

The reality is that the obvious shortcomings of glass buildings rarely received the attention they warranted. Some early critics raised objections. Perhaps the most outspoken was Swiss architect Le Corbusier, who in the late 1940s launched an attack on the design of the UN Secretariat, arguing that its large and unprotected glass surfaces were unsuitable for the climate of New York.


But all too often, historians and architects have focused on the aesthetic qualities of glass architecture. The Crystal Palace, in particular, was portrayed as a pristine icon of an emerging architecture of glass and iron. Yet in reality, much of the glass was covered with canvas to block out intense sunlight and heat. Similarly, the smooth glass facades of Chicago’s early glass towers were broken by opened windows and blinds.

There’s an an urgent need to take a fresh look at urban architecture, with a sense of environmental realism. If de Blasio’s plea for a more climate conscious architecture is to materialise, future architects and engineers must be equipped with an intimate knowledge of materials – especially glass – no less developed than that held by 19th century gardeners.

The Conversation

Henrik Schoenefeldt, Senior Lecturer (US: Associate Professor) in Sustainable Architecture, University of Kent.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

 
 
 
 

Leeds is still haunted by its pledge to be the “Motorway City of the Seventies”

Oh, Leeds. Image: mtaylor848/Wikimedia Commons.

As the local tourist board will no doubt tell you, Leeds has much to be proud of: grandiose industrial architecture in the form of faux-Egyptian temples and Italian bell-towers; an enduring cultural legacy as the birthplace of Goth, and… motorways. But stand above the A58(M) – the first “urban motorway”  in the country – and you might struggle to pinpoint its tourist appeal.

Back in the 1970s, though, the city council was sufficiently gripped by the majesty of the motorways to make them a part of its branding. Letters sent from Leeds were stamped with a postmark proudly proclaiming the city's modernity: “Leeds, Motorway City of the Seventies”.

Image: public domain.

During the 1960s, post-war optimism and an appetite for grand civic projects saw the rapid construction of motorways across England. The construction of the M1 began in 1959; it reached Leeds, its final destination, in 1968. By the early 1970s the M62 was sweeping across Pennines, and the M621 loop was constructed to link it to Leeds city centre.

Not content with being the meeting point of two major motorways, Leeds was also the first UK city to construct a motorway through the city centre: the inner ring road, which incorporates the short motorway stretches of the A58(M) and the A64(M). As the council put it in 1971, “Leeds is surging forward into the Seventies”.

The driving force behind Leeds' love of motorways was a mix of civic pride and utopian city planning. Like many industrial cities in the North and Midlands, Leeds experienced a decline in traditional manufacturing during the 1960s. Its position at the centre of two major motorways seemed to offer a brighter future as a dynamic city open for trade, with the infrastructure to match. In response to the expansion of the roads, 1970s council planners also constructed an elevated pedestrian “skywalk” in an attempt to free up space for cars at ground level. Photos of Leeds from that time show a thin, white walkway running through blocky office buildings – perhaps not quite as extensive as the futuristic urban landscape originally envisaged by planners, but certainly a visual break with the past.

Fast forward to 2019 and Leeds’ efforts to become a “Motorway City” seems like a kitsch curiosity from a decade that was not always known for sustainable planning decisions. Leeds’s historic deference to the car has serious consequences in the present: in February 2019, Neville Street – a busy tunnel that cuts under Leeds station – was found to contain the highest levels of NO2 outside London.

City centre planners did at least have the foresight to sink stretches of the inner motorways below street level, leaving pedestrian routes largely undisturbed. Just outside the centre, though, the roads can be more disruptive. Sheepscar Interchange is a bewildering tangle of arterial roads, Armley Gyratory strikes fear into the hearts of learner drivers, and the M621 carves unsympathetically through inner-city areas of South Leeds with pedestrian access restricted to narrow bridges that heighten the sense of a fragmented landscape.

 

Leeds inner ring road in its cutting. Image: author provided.

 

The greatest problem for Yorkshire's “Motorway City” in 2019, however, is not the occasional intimidating junction, but the complete lack of an alternative to car travel. The dire state of public transport in Leeds has already been raised on these pages. In the early 20th century Leeds had one of the most extensive tram networks in the country. The last lines closed in 1959, the same year construction began on the A58m.


The short-sightedness of this decision was already recognised in the 1970s, as traffic began to build. Yet plans for a Leeds Supertram were rejected by successive Conservative and Labour governments unwilling to front the cost, even though smaller cities such as Newcastle and Sheffield were granted funding for light transport systems. Today, Leeds is the largest city in the EU without a mass transit system. As well as creating congestion, the lack of viable public transport options prevents connectivity: the city's bus network is reasonable, but weaker from East to West than North to South. As a non-driver, I've turned down jobs a short drive away that would be a logistical impossibility without a car.

Leeds' early enthusiasm for the motorway was perhaps premature, but there are things we can learn from the 1970s. Whatever else can be said about it, Leeds' city transport strategy was certainly bold – a quality in short supply today, after proposals for the supertram were watered down to a trolleybus system before being scrapped altogether in 2016. Leeds' rapid transformation in the 1960s and 70s, its grandiose visions of skywalks and dual carriageways, were driven by strong local political will. Today, the long-term transport strategy documents on Leeds City Council's website say more about HS2 than the need for a mass transit system within Leeds itself, and the council has been accused of giving up the fight for light rail and trams.

Whilst central government's refusal to grant funds is the greatest obstacle to Leeds' development, the local authority needs to be far more vocal in demanding the transport system the city deserves. Leeds' desire to be the Motorway City of the Seventies might look ludicrous today, but the political drive and utopian optimism that underpinned it does not.