Acknowledgements This research received funding from the European community’s 7th framework programme FP7/2007–2013 under grant agreement no. 226532, as well as from Senternovem, the Dutch governmental agency for sustainability and innovation from the Ministry of Finance (grant no. EOSLT06020), and was supported by Alliander. The authors would like to thank Marjolein Helder and Kirsten Steinbusch for their useful comments.