Among the more vexing problems of the energy transition is the task of eliminating emissions from the world’s buildings. Because they burn fuel for heat and hot water, buildings are directly responsible for 6 percent of global emissions. But they also consume a substantial share of the world’s electricity, making them indirectly responsible for a much larger share of emissions.

The technological path to eliminating the direct emissions is clear: all the energy services in buildings need to be converted to electricity, with heating and (where necessary) cooling provided by devices called heat pumps. These are machines that heat or cool a building not by generating heat but by moving it around, in the same way a refrigerator does but at a larger scale. They can be 300 to 400 percent efficient, meaning they can inject an amount of heat energy into a building three to four times larger than the electricity they use to do so. To further minimise electricity usage and the cost of operating these units, buildings need to be tightly insulated, with air gaps sealed, and draughty windows may need to be replaced.

If the technological path is clear, the legal path is anything but. Ownership of buildings is fragmented, and any public policy designed to speed up the transition of buildings must grapple with this complexity. To cite a simple example, the owner of an apartment building has the right to decide what kind of appliances it will have and what efficiency standards they will meet, but it is the tenants who must pay the energy bills. This gives the owner no incentive to fix up the building or install efficient appliances, while the tenant with a direct financial stake in those decisions has little or no ability to influence them — a problem known as the “split incentive”. Similar problems apply in commercial buildings, but they are afflicted by another difficulty: serious expertise may be required to run the complex air-handling systems in larger buildings, and it is often lost as buildings age and change hands. Research has found that many commercial buildings operate far below their maximum potential efficiency.

Decades of work on these problems has led to limited progress. As a result, many experts have recently concluded that the only way to achieve society’s goals will be to impose legally enforceable mandates on building-energy use. In the past few years, such mandates have begun moving onto the statute books, but there is a long way to go to achieve universal coverage of the building stock.

An obvious and immediate task is stop constructing new buildings that are going to need fixing in a few years — that is, to adjust the building codes and related requirements now, so that newly constructed buildings are fit for purpose in 2050. Dozens of towns in California, and a handful elsewhere in the United States, have banned the installation of new gas hook-ups in buildings, requiring that they be all-electric when constructed. California also requires solar panels on all new homes, to offset as much of the electricity use as possible. In many jurisdictions around the world, however, building codes are woefully out of date, and need to be revised to incorporate the latest standards in energy efficiency.

A new type of law is being adopted by forward-looking jurisdictions in the United States. Several cities — including Washington, D.C. and New York City — have established “building energy performance standards”, essentially requiring year-by-year reductions in the energy use of buildings. For now, the laws apply to large offices and other commercial buildings, and should create an expanded market for renovating buildings and running them properly. The European Union has adopted a scheme in which larger buildings are assigned a letter grade according to how much energy they use, but these ratings are widely perceived as inaccurate, and it is not clear whether this name-and-shame policy has stirred any increase in renovations. The EU is beginning to consider mandates, but only for the worst-performing buildings.

The building-energy problem has become exceedingly urgent, for the simple reason that so little progress has been made in solving it. We hope that governments around the world are closely watching the policy experiments being undertaken in the leading jurisdictions, and stand ready to copy the ones that work. It can be done: a decade ago, governments made a strong push to get building owners and consumers to adopt new light bulbs based on light-emitting diodes, or LEDs. The result was a dramatic scale-up in the market and an equally dramatic march down the price curve for LED technology. That success shows what can be done with creative public policy when governments really try.