The National Renewable Energy Laboratory (NREL) has a very informative presentation on Zero Energy Homes.
Link: NREL: Visitors Center – Presentations.
Zero Energy Homes: What, How, and Why (PDF 7.4 MB) December 19, 2007 by Paul Norton
http://www.nrel.gov/visitors_center/pdfs/norton_zeh_power_lunch_1207.pdf
