This study evaluates the CO2 reduction (effectiveness) and costs per tonne of CO2 reduction (efficiency) of the Sustainable Energy Investment Subsidy Scheme (Investeringssubsidie duurzame energie, ISDE) in the period 2019-2023. In addition, we evaluate the capacity to act (the ability to take action and persevere, even in the face of setbacks) of ISDE users.
The study combined the results of multiple research methods to draw conclusions and make recommendations. The methods applied were a literature review, an analysis of application data, a user survey, a choice experiment among potential users and interviews.
The main findings are: • In the period 2019-2023, more than 760,000 measures were implemented with the assistance of ISDE. The total market value of these measures amounted to approximately € 3.6 billion, of which more than € 1.1 billion was covered by ISDE. ISDE has mainly been used for the purchase of heat pumps and, to a lesser extent, for insulation measures. • These investments have led to a gross CO2 reduction of 663 ktonnes per year. If we calculate the part of the expected reduction that would not have been achieved without ISDE, this is an annual CO2 reduction of 95 to 334 ktonnes. • The ISDE has a gross efficiency of € 94 per tonne of CO2 reduction. If only the additional CO2 savings are taken into account, the net efficiency ranges from € 147 to € 552 per tonne of CO2 reduction. The effectiveness varies considerably depending on the technique used. • In broad terms, the doability of the applicants is in line with the actions required to make an investment with the assistance of ISDE.
The report includes recommendations for improving the scheme. This evaluation was carried out jointly by CE Delft and SEO Amsterdam Economics (SEO Economisch Onderzoek).