How green is your skyscraper? Why the most sustainable buildings might be low-rise

Well, this one's pretty green. The Empire State Building, in its St Patrick's Day gladrags. Image: Getty.

The fact a controversial cornucopia of towers is coming London’s way is well known – and some who support this development claim that towers are “greener” than low-rise living.

But are they? My new research project at UCL’s Energy Institute (conducted in association with Create Streets) will try to discover if high-rise buildings are more energy-intensive than equivalent low-rise buildings. At present the evidence is uncertain, but there are suggestive hints. We intend to test them.

Many variables can affect tall buildings’ energy use – and only some of them relate to height. There is the use of energy in lifts. There is the use, or not, of air conditioning. There can be important differences due to building construction, especially between glass curtain walls and solid walls, since rates of heat loss are greater through the glass. Finally, there will be effects related to the local environments of buildings – such as orientation, overshadowing and exposure to sun and wind.

There is some evidence on the relationship between height and energy use. A 2003 study of 20 comparable Hong Kong office towers found that, as high increased, there was a steady increase in energy too. Each additional storey added on average 3 kilowatt hours per M2.

But the use per M2 for lighting and – perhaps surprisingly – lifts did not increase with height. The biggest increase was in the energy used for heating, ventilating and air conditioning. The Hong Kong climate is hot and steamy: we would expect heavy loads for air conditioning. But these were greater, per unit of floor area, the taller the building.

The energy element of the English Housing Survey provides evidence of the relationship between energy use and height in tall residential buildings. A preliminary analysis of data on both low- and high-rise purpose-built flats shows that the latter use on average more than twice the amount of electricity annually (although the sample is small).

That said, there have been studies that have shown little or no difference in energy use with height. Aedas Architects analysed theoretical designs for tall office buildings, using simulation models, and found only small increases in energy intensity with height.

Researchers at the LSE carried out a study of energy use for heating in residential buildings of many different types. They found that energy use decreased with height. However, they too were working with simulations. Furthermore, their sample only included buildings up to 11 storeys.


Why might we expect energy use to increase with height? The obvious characteristic of tall buildings is that they stick up above their neighbours: they are exposed to higher winds. Data from the Chartered Institution of Building Services Engineers shows that wind speeds do indeed rise with height

And higher winds can contribute to increased energy consumption in several ways. They remove heat from the surfaces of buildings. They increase drafts, meaning that the air inside requires more heating or cooling. And they can increase the rates of conduction of heat through the building’s envelope, especially through glazing. Tall buildings tend also to be more exposed to the heat of the sun, and are less likely than low-rise to be overshadowed by trees or other buildings. This can lead to increased energy requirements for cooling in summer.

It seems at least possible that such effects are insufficiently represented in the simulation models used to estimate energy consumption during the design of tall buildings. This could lead to underestimates of predicted energy consumption in practice.

It’s sometimes suggested that a concentration of tall buildings around public transport hubs can help shift travellers from cars to buses or trains, and so reduce energy consumption in transport. This may be true. However, it is an argument for higher densities rather than skyscrapers, as such.

Some researchers have looked at the potential for “green” retrofitting of existing tall buildings. Valuable as this work is, it seems possible that most, if not all, of the conservation measures and renewable technologies employed in “green” or low-energy skyscrapers could equally be applied – perhaps with greater effectiveness – in low-rise buildings. One could also imagine that the potential for adaptation and refurbishment would be greater in low buildings than in tall ones. Might the most sustainable skyscraper not be a skyscraper at all?

Philip Steadman is professor of urban and built form studies at University College London. This article is adapted from an essay he wrote for Create Streets.

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In many ways, smart cities are really very dumb

Rio de Janeiro’s control centre. Image: Getty.

It’s not news that anything and everything is increasingly being prefaced with “smart”: phones, watches, homes, fridges, and even water (yes, smartwater exists). And it’s not unintentional either. 

Marketeers know that we, the public, are often stupid enough to believe that thanks to their technology, life is better now than it was way back in, say, the primitive Nineties. Imagine having to, like a Neanderthal, remember how to spell words without an autocorrecting algorithm, or open the fridge door to check if you’d run out of milk, or, worse still, interact with actual people.

So it’s hardly surprising that we’re now also witnessing the rise of the so-called “smart cities”; a concept which presupposes that cities that are not technologically  “smart” are dumb, which, as anyone interested in the millennia-old history of cities — from the crypto-currency grain storage algorythms of ancient Mesopotamia to the complex waste infrastructure of ancient Rome, to London’s public transport infrastructure — will know, is not true.

Deployed in these smart cities are cameras and other networked information-gathering devices, load cells and other “sensing devices” detecting passing pedestrians and vehicles, audio surveillance devices listening for gunshots – and even vending machines equipped with biometric sensors to recognise your face. This is not to mention beacon technology — tiny anonymous looking black boxes hidden in trees and on lampposts — which transmits advertising, offers and other information directly to smart phones in the vicinity. 

If that doesn’t seem sinister enough, take, for example, Rio de Janeiro, where, in 2014, the International Business Machines Corporation designed a mammoth “control centre” that integrates data from 30 agencies for the city’s police. 

Described by the Guardian as having “the functionality of a Bond villian’s techno lair”, the then local mayor, Eduardo Paes, claimed the centre was making the city safer while using technology to deploy its “special” police unit to carry out the state’s “pacification programme”. Launched in 2008, the programme, which aims to push out drug gangs from Rio’s favelas, has been criticised by Amnesty International: “in January and February 2017 in Rio de Janeiro alone, at least 182 people were killed during police operations in marginalized neighbourhoods (favelas) – a 78 per cent increase in comparison to the same period in 2016”.

Sinister or not, as smart cities grow, they create new problems. For example, as urbanist Adam Greenfield writes in Radical Technologies: The Design of Everyday Life, neither the algorithms nor their designers are subject to the ordinary processes of democratic accountability – a problem that international academics are currently attempting to tackle.  


“We need to understand that the authorship of an algorithm intended to guide the distribution of civic resources is itself an inherently political act,” writes Greenfield. “The architects of the smart city have utterly failed to reckon with the reality of power.”

The Real Smart Cities project, founded by Dr Gerald Moore, Dr Noel Fitzpatrick and Professor Bernard Stiegler, is investigating the ways in which so-called “smart city” technologies present a threat to democracy and citizenship, and how digital tools might be used create new forms of community participation.

Fitzpatrick is critical of current discourses around smart cities, which he says “tend to be technical fixes, where technology is presented as a means to solve the problems of the city.” The philosophy underpinning the project is “that technologies function as forms of pharmacology”, he adds, meaning that they can be both positive and negative. “The addictive negative effects are being felt at an individual and collective level.” 

An example of this lies in the way that many of these smart cities replace human workers with disembodied voices — “Alexa we need more toilet roll” — like those used to control the Amazon Echo listening device — the high priestess of smart home. These disembodied voices travel at the speed of light to cavernous, so-called “fulfilment centres”, where an invisible workforce are called into action by our buy-it-now, one-click impulse commands; moving robotically down seemingly endless aisles of algorithmically organised products arranged according to purchase preferences the like of which we never knew we had — someone who buys a crime novel might be more likely to go on and buy cat food, a wireless router, a teapot and a screwdriver. 

Oh to be the archeologists of the future who while digging through mounds of silicon dust happen upon these vast repositories of disembodies voices. That the digital is inherently material and the binary of virtual/real does not hold — there is no cyberspace, just space. Space that is being increasingly populated by technologies that want to watch you, listen to you, get to know you and sense your presence.

One project looking to solve some of the problems of smart cities is that of the development of a “clinic of contribution” within Pleine Commune in greater Paris (an area where one in three live in poverty).This attempts to deal with issues of communication between parents and children where the widespread use of smartphones as parental devices from infancy is having effects on the attention of young children and on the communicative abilities between parents and children. 

This in turn forms part of a wider project in the area that Stiegler describes as “installing a true urban intelligence”, which moves beyond what he sees as the bankrupt idea of smart cities. The aim is to create a “contributory income” in the area that responds to the loss of salaried jobs due to automation and the growth and spread of digitisation. 

The idea being that an income could be paid to residents, on the condition that they perform a service to society. This, if you are unemployed, living in poverty and urban deprivation, sounds like quite a simple and smart idea to try and solve some of the dumb effcts of the digital technology that's implemented in cities under the ideology of being “smart”.