The US Department of Energys new definition of a zero emissions building is pure doublethinkIn June this year, the US Department of Energyreleased a National Definition of a ZeroEmissions Building in an effort, it claims, to help decarbonise the building sector. ADepartment of Energy certainly seems like thesort of agency that should know exactly the amount of, well, energy, it takes to construct a building, and the associated emissions. Yet the definition revolves around operational energy use that is, a building can be zero emissions ifit burns no fossil fuels on-site and uses clean energy during its life.This is the latest example among many disappointing institutional definitions of net zero and zero emissions. The Greater London Assemblys vaunted 2030 net zero pledge, for example, admits that embodied emissions in goods, services, or construction projects are notincluded in [its] analysis while recognising, inthe same breath, that actions to address these emissions must be considered as part of wider climate change mitigation strategies. These definitions seem almost designed to maintain astate of Orwellian doublethink, allowing us tosit happily in our steel, glass and concrete buildings, assured of their environmental impeccability because they have a few solar panelsand an air source heat pump.The construction industry struggles to come toterms with embodied carbon as a concept. Theidea that organisations and individuals, while not burning coal themselves, should still assume responsibility for the emissions that result from making the materials they specify isunappealing. According to the Chatham House think tank, the cement industry alone accounts for around 8 per cent ofglobal emissions. Insome ways,embodied carbon is more criticalthan operational energy use, because itisproduced when the building isbuilt rather than over its lifespan. These emissions damage the climate here and now rather than at an abstract point in the future.When challenged, designers and developers have a few stock explanations for their inability to depart from the status quo. It is frequently claimed that timber is too expensive to insure; the building insurance industry is spooked by theprospect of rot and fire associated with this new and innovative construction material. But bizarrely, no one worries about the abundance of crumbling concrete buildings and infrastructure that has barely survived half a century. Neither does the fact that many of the worlds towns and cities are full of centuries-old wooden housing seem to persuade this industry of the materials durability. Do insurers realise that their actuarial decisions are a major impediment to moving to a replenishable construction material?Insome ways,embodied carbon is more criticalthan operational energy use, because itisproduced when the building isbuilt rather than over its lifespanIt is also often said that low-carbon alternatives are too expensive. This is a central paradox in the sustainability debate; building sustainably should mean using less material and less energy. To produce concrete, for example, limestone with a compressive strength of 60N/mm2 to 150N/mm2 is crushed and burned in a rotary furnace to create cement. It is then mixed withsand (which is nowincreasingly scarce), freshwater and more crushed stone in a batching plant. Often afleet oflorries with revolving tanks then deliver thisproduct to site, where it is poured into hugestructures erected as moulds and filled withreinforcing steel. The resulting material willhave a strength of 40N/mm2. Why are these processes lower cost than the simpler, shorter and often more local processes of using the limestone in its natural form?The OECD reports that manufacturing and energy subsidies are hard to pin down, but suggests that aluminium and cement are the highest subsidy recipients globally, with steel ateighth place. But fossil fuel and industrial subsidies do not explain the cost gap. It seems more likely that the volume of timber and stone construction is still too low to breed an industry of mature efficiency to rival the mass production of high-carbon materials.In response to benchmarking by organisations such as the RIBA or the Green Building Council, designers are starting to measure embodied carbon. It is hoped that when this practice becomes more common and standardised it willopen the door to regulatory limits that may make it far less easy to build with steel, concrete and brick, all while calling it zero emissions. Fiscal measures such as carbon credits and the EUs carbon border tax should push up the relative cost of high-carbon materials and make it more economical to use low-carbon ones instead. This could in turn promote industrial interest in low-carbon materials.Despite these optimistic possibilities, the outlook is still gloomy. The pushback from the industry and well-oiled lobbying organisations is, and will continue to be, significant and effective. The US Department of Energys misleading zero emissions building definition suggests that the lobbies have the ear of the government of the worlds biggest economy. Despite the brave efforts of a few designers and developers around the world, the broader construction sector is very slow to adopt the kind of radical change tobuilding practices that the climate crisis demands. It seems it is unlikely to be forced todo so especially if governing bodies cannot get the fundamental definitions right.Lead image:Limestone, seen below quarried in the UKs Peak District, has a compressive strength of60N/mm2 to150N/mm2. It is transformed into cement by being crushed and burned, thenmixed with aggregate to make concrete a weaker building material at40N/mm2. The process is carbon intensive at every stage, but such embodied carbon emissions are rarely accounted for in official definitions of net zero or zero emissions buildings. Credit:Paul White / Alamy2024-10-23Kristina RapackiShare AR October 2024Buy Now