1. Engelund Thomsen , K. ; Wittchen , K. B. ; EuroACE 2008 .European national strategies to move towards very low energy buildings. Aalborg : SBi, Statens Byggeforskningsinstitut . 33 p.
2. Feist , W. 2007 . PHPP: far more than just an energy calculation tool . [Online] Passive Building Institute, Darmstadt [accessed 17 June 2011]. Available from Internet:http://www.passivhaustagung.de/Passive_Building_E/PHPP.html
3. IWEC source data 2001 . International Weather for Energy Calculations (IWEC) . [Online] American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), Atlanta [accessed 20 April 2011]. Available from Internet:http://apps1.eere.energy.gov/buildings/energyplus/weatherdata_sources.cfm#IWEC