Although the worst possible effects of climate change have been signalled for some time, the special report on the impacts of global warming of 1.5ºC, issued by the UN Intergovernmental Panel on Climate Change late last year, stressed the urgency with which these possibilities need to be confronted. In 2018, greenhouse gas (GHG) emissions rose to an all-time high, up 2.7% on 2017 - during which emissions were 1.6% higher than the 2014-16 plateau.
Action by right-thinking cities looks to be ever more important to the future of the planet, particularly when we consider the rate of urbanisation. The leaders of 20 of the planet’s largest cities have committed to reducing their GHGs by 80-100% by 2050 or sooner to support the global transition to a carbon-neutral economy.
The Carbon Neutral Cities Alliance (CNCA) was born in Copenhagen in June 2014 in response to the fact that cities are responsible for nearly 75% of the world’s total greenhouse gas emissions. As well as encouraging leading cities such as Berlin, Seattle and Melbourne, to make their own commitments and publicise their progress, the CNCA directorate has created a framework to guide cities through decarbonisation.
Alliance cities have very varied building stock profiles and market conditions throw up different challenges. Despite this mix, the CNCA reports that members: “tend to share a set of general building energy efficiency conditions, a vision for what the redesigned system will look like and common barriers to system change.” The CNCA’s framework goes on to lay out the typical categories of building-level energy conservation methods:
Building power sources including renewables, combined heat and power and clean energy procurement;
Heat and cooling such as high-performance insulation, efficient HVAC, and improved-efficiency fan and pump motors;
Building management including annual building maintenance upgrades, standardised building operating manuals and building energy management systems;
Lighting and windows which covers LEDs and reduced power densities, daylighting, occupancy sensors and high-performance windows, and;
Other measures such as changing occupant behaviour, better data centre management and thermal storage.
In navigating these categories, cities “share a strategic balancing act: how much to push for efficiency and resulting reductions in demand for energy, versus how much to push for reduction of the carbon content of energy supply to buildings”, the CNCA directorate says in its framework.
Some CNCA cities are trying to ascertain the best mix of methods to achieve GHG reduction. Boston officials, for instance, are analysing how different policies can reduce carbon emissions from new and existing buildings. The city, which reduced its emissions 25% below 2005 figures five years ahead of schedule, developed a database of building models representing local buildings and their uses including single and multi-family homes, offices, schools, and more. For each building type, they are looking at various energy conservation measures, such as the best choice of insulation and assessing the emissions reductions, costs and benefits of the measures.
Of course, there are many and varied impediments to achieving near or zero-GHG emissions by 2050, which might also vary by city and city type. High growth cities with sharply increased design standards will have to invest in building control enforcement to meet targets.
And all cities face the “split-incentive” problem whereby a building’s owners do not benefit from energy efficiency measures - tenants do. As a result of these and other drawbacks, says CNCA, developers and landlords are not incentivised to invest in energy efficiency at sufficient scale to meet the cities’ decarbonisation goals. The future, in other words, is regulation that ultimately allows us to achieve these goals on a global scale to avoid the worst impacts of climate change.