Principles and practice of zero energy buildings in Estonia [Online resource]Arumägi, Endrik; Kalamees, TargoSustainable Built Environment : Transition Zero : conference publication of the Utrecht SBE16 Conference on 7-8 April 20162016 / p. 147-155 : illhttp://hu-conferenties.nl/getmedia.php?Media=sbe16/sbe16.pdf&Online=true