1. Environmental and Energy Systems Studies, Lund University, PO Box 118, Lund SE-221 00, Sweden
2. China Energy Group, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USE-mails: and
3. Sustainable Energy Partnerships, 12 Hanford Place, Tarrytown, NY 10591, USE-mail:
4. Institute of Building Environment and Energy, China Academy of Building Research, 30 Bei San Huan Dong Lu, Beijing 100013, ChinaE-mail: