Analysis of heating energy of ventilation and underground heat exchanger in North European passive housesVoll, Hendrik; Seinre, Erkki; Sööt, MatiInternational journal of energy and environment2012 / p. 92-100 : ill https://www.academia.edu/100156656/Analysis_of_Heating_Energy_of_Ventilation_and_Underground_Heat_Exchanger_in_North_European_Passive_Houses