Awarding the Stirling Prize to Foster + Partners for its Bloomberg building sends the wrong message and risks runaway global warming. We need a new approach to sustainability says Phineas Harper.

Sustainability has been seen for years by architects as a worthy but tedious constraint. Tick-box regulations have been adopted by a compliant but begrudging profession. Sustainable design was necessary but not sexy.

Yet these days seemingly all buildings claim to be sustainable. Ken Yeang's tree-festooned skyscrapers in Kuala Lumpur are "saving the planet by design". The Interlace, Ole Scheeren's hexagonal stacks of 1,040 apartments in Singapore, are a "synthesis of tropical nature and habitable urban space". Bjarke Ingels' waste-to-energy power plant, which will puff a ton of CO2 into the Copenhagen air with every 10 smoke rings is the "cleanest in the world".

An increasingly irreconcilable variety of architectural strategies claim to be united by a common passion for ecology – green is the new black.

Architecture, it seems, is acting

Another much-touted triumph for the planet is Foster + Partner's £1 billion European headquarters for stock-market data giant Bloomberg. This week the project scooped the RIBA Stirling Prize partly in recognition of its ecological credentials, widely billed as "the world's most sustainable office building".

Good timing too, as the Intergovernmental Panel on Climate Change's Incheon Report is as grave as it is categorical: a mean global temperature rise of 1.5 degrees is the tipping point for global catastrophe, with only 12 years on the clock to act.

Architecture, it seems, is acting. Across the world, environmental performance standards are driving up the energy efficiency of new buildings. BREEAM in the UK, LEED in the US, the Estidama in Abu Dhabi, Green Star in Australia and, arguably the most ambitious standard, the China Green Building Label.

Bloomberg scooped the highest BREEAM certification possible of Outstanding – surely if there is an architecture that can limit warming to the 1.5 degrees needed, this is it?

It isn't. "Sadly all this is not enough" says Spencer de Grey, head of design at Foster + Partners, presenting the project in Beijing.

De Grey showed research comparing international building performance standards against their knock-on share of mean temperature rises. His conclusion was galling. Even if the highest standards were universally adopted, we would be on track for a catastrophic three to five degrees of global warming. Bloomberg, according to De Grey, is a three-degrees building.

Let that sink in. Even the "world's most sustainable office building" is fuelling global warming more than double what we can afford. And De Grey's research did not even take into account the embodied energy of the 10,000 tonnes of sandstone cladding, the vast bronze facade fins or the deep foundations required to take their weight.

In the week the UN warned of an on-coming catastrophe, the RIBA was toasting a project its own designers says is hastening that catastrophe's arrival

In the week the UN warned of an on-coming catastrophe, the RIBA was toasting a project its own designers says is hastening that catastrophe's arrival.

The billion pound question is, if an unprecedented budget and the unrivalled expertise of Foster + Partners was not enough to make Bloomberg sustainable, then what on earth could have been?

The answer is that its a bad question. Bloomberg is the oil in wheels of the global stock market. You can't make its corporate headquarters ecological much as you can't wage an ethical nuclear war or build a sustainable airport.

We have sold ourselves on the idea that we can save the planet by making the current growth-based economy ever-more efficient. Smart cities will optimise commuter patterns, high-performance materials will span greater distances with reduced mass. Reusable coffee cups will consume less energy than disposable ones. Yet the sharp truth is that simply making the status quo more efficient, rather than shifting to a fundamentally different paradigm, as De Grey has shown, is a doomed strategy.

Simply making the status quo more efficient, rather than shifting to a fundamentally different paradigm, is a doomed strategy

This is an enormous conundrum for architects everywhere, cutting to the heart of any claim to social or ethical practice. Are we really content to continue in this trajectory? Do we think that enough carbon savings can be made elsewhere from transportation or agriculture that construction can continue unfazed?

You may have cut out meat and cut down flying (and if you haven't, what the hell are you thinking?) but if you're still specifying concrete frames and demolishing, rather than upgrading old stock, you're firmly committing us to three degrees and more.

In any case, we have long since reached the limit of what can be achieved through negative messages. The gravity of global warming's effects have been known and campaigned on for decades but western democracies are not acting. This year the British government approved a new runway for Heathrow and imprisoned activists Richard Loizou, Richard Roberts and Simon Roscoe-Blevins for protesting against fracking. The warnings aren't getting through. We need a new tactic.

For De Grey and his practice, it seems the tactic is clear. If the world's most sustainable office building isn't enough to save the planet, get a new planet.

A better world is possible and architecture has a critical role to play in the journey

Foster + Partners has produced papers on terraforming Mars with autonomous drones and 3-D-printed lunar bases. In 2014 it completed a spaceport for Richard Branson. Once the climate movement were mocked as utopians with dreams of low-carbon economies and renewable energy.

Today that eco-warrior manifesto feels eminently practical compared to a new breed of specious space-colonising architect. This is not bold visionary thinking – it is escapism, seductive only to those who can imagine no alternative to infinite economic growth despite a finite planet.

What we can learn from Foster + Partners however is the power of the positive message. They understand better than most the challenges ahead but are not wringing their hands in despair. Mars is the wrong answer to the wrong question but it is right that a better world is possible, and architecture has a critical role to play in the journey. Perhaps not through awarding stone-clad cathedrals of capitalism Stirling Prizes, but through redesigning the economic framework within which all architecture is made.

The profession is limbering up for the fight ahead. Not before time, stopping global warming is finally becoming cool.

Photograph is by Nigel Young/Foster + Partners.