A carbon price will not achieve all abatements, because market imperfections may distort the price signal. Many efficiency measures remain untaken as a result of market imperfections (see figure 4), such as misaligned incentives or information gaps among end-users (see figure 6). This is most apparent in the building and transport sectors, but applies to some extent in power and industry too. To overcome this, governments should complement the carbon price by establishing minimum requirements for energy and CO2e efficiency for areas not well served by the market. Requirements should be designed to stimulate growing efficiency over time.