The government introduces a subsidy for low-emission home-heating systems. Figure 1 shows the market before and after the subsidy.

Using Figure 1, analyse how the subsidy may increase the consumption of low-emission heating systems.
127 exam-style questions on OCR GCSE Economics 3.8 Limitations of markets, covering 3.8.1 Positive and negative externalities, 3.8.2 Policies to correct externalities, 3.8.3 Impact of externality policies, and 3.8.4 Costs and benefits of externality policies. Each one has a worked solution and a mark scheme showing where the marks go.