| By Olivia Rudgard Is it really possible to create a building that leaves the world a better, greener, more sustainable place than it was before? It’s a practical question that also has a bit of a philosophical bent to it. It’s similar to one many of us climate journalists ask ourselves over and over again: What does it mean to live sustainably, when to live is to cause harm? In my story today, I examine a new trend for architects and developers to claim “positive” impact from their projects — whether in carbon or energy. It’s a laudable aim that goes a step further than the usual “carbon neutral” or “net zero” goals, which only seek to cancel out that negative impact. As regulatory pressure has stepped up, companies are increasingly looking to claim the highest standards in their buildings, both in materials and construction and in energy performance. There are many ways to go about this. One Scandinavian group has taken the approach of making a building effectively a power plant, sharing much of its excess energy around, to cancel out the climate costs of construction and operation. Alternatively, a team that launched a new hotel in Denver used lower-carbon concrete, planted thousands of trees and now encourages its guests not to drive. Meanwhile, architects in Tasmania used their mass-timber office to embark on research about whether a building could store more carbon than it emits, based on the embodied carbon in materials like timber and straw.  Powerhouse Brattørkaia is clad with thousands of square meters of solar panels. It produces, on average, more than twice as much electricity as it consumes daily, according to its architects. Photographer: Ivar Kvaal/powerhouse.no/en Talking to the people behind these projects, I was struck by the diversity of their approaches. While all of them wanted to reduce the environmental impact of their buildings and were deeply concerned about the impact of their industry on the planet, they had different ideas about what that actually meant. And while these might all be marquee projects in their own way, in practice there was little to unify them. In the UK, there are efforts underway to create net-zero standards for buildings by asking developers to align their projects to the Paris Agreement’s stretch goal of keeping global warming to 1.5C. (Although whether that target is even still possible is being keenly discussed on the sidelines of COP29.) Currently, experts told me, there’s no universally accepted industry definition for a carbon-negative or climate-positive building, and it may not be even possible to establish one based on the current gaps in our knowledge.  For instance, construction materials like cement and steel have eye-watering carbon footprints, though that is slowly improving. Timber might be a better material but it’s hard to say for sure. Then there’s the challenge of calculating the impact of shipping materials thousands of miles across the world. Also, what happens to the building at the end of its life? Does it go into an incinerator, to landfill or to make something new? What about the carbon in soil dug up for foundations, or the forests degraded by the disturbance of timber extraction? The questions become even more dizzying if you include other, less quantifiable “harm” factors, like biodiversity loss and social impact. Most projects are not addressing these issues yet, and new buildings are going up at a ferocious pace — a rate equivalent to adding an entire New York City to the world, every month, for 40 years, according to one calculation. A proper new standard that requires buildings to align to 1.5C might be one solution, including mandates to reuse and repurpose existing buildings as much as possible. This would work particularly well in places like the US and Europe, where there is available building stock to do this. These pioneering “positive” buildings might be important, says Tom Wigg, a senior adviser at the UK Green Building Council, who is part of the efforts to create a net zero standard, “but we have a scale issue. This needs to happen at scale now.” Read the full story for free on Bloomberg.com. | 
