Editing Heat recovery ventilation (section)

=== Run-around systems ===
Flaga-Maryanczyk et al.<ref>{{Cite journal|last1=Flaga-Maryanczyk|first1=Agnieszka|last2=Schnotale|first2=Jacek|last3=Radon|first3=Jan|last4=Was|first4=Krzysztof|date=January 2014|title=Experimental measurements and CFD simulation of a ground source heat exchanger operating at a cold climate for a passive house ventilation system|journal=Energy and Buildings|volume=68|pages=562–570|doi=10.1016/j.enbuild.2013.09.008|bibcode=2014EneBu..68..562F |issn=0378-7788}}</ref> conducted a study in Sweden which examined a passive ventilation system which integrated a run-around system using a ground source heat pump as the heat source to warm incoming air. Experimental measurements and weather data were taken from the passive house used in the study. A CFD model of the passive house was created with the measurements taken from the sensors and weather station used as input data. The model was run to calculate the effectiveness of the run-around system and the capabilities of the ground source heat pump.

Ground source heat pumps provide a reliable source of consistent thermal energy when buried 10–20 m below the ground surface. The ground temperature is warmer than the ambient air in winter and cooler than the ambient air in summer, providing both a heat source and a heat sink. It was found that in February, the coldest month in the climate, the ground source heat pump was capable of delivering almost 25% of the heating needs of the house and occupants.<ref name=":2" />