Editing Heat recovery ventilation (section)

=== Phase change materials ===
The majority of research interest in PCMs is the application of phase change material integration into traditional porous building materials such as concrete and wall boards. Kosny et al.<ref>{{Cite book|title=Kosny J, Yarbrough D, Miller W, Petrie T, Childs P, Syed AM, Leuthold D. Thermal performance of PCM-enhanced building envelope systems. In: Proceedings of the ASHRAE/DOE/BTECC conference on the thermal performance of the exterior envelopes of whole buildings X. Clear Water Beach, FL; 2–7 December 2007. p. 1–8.}}</ref> analyzed the thermal performance of buildings that have PCM-enhanced construction materials within the structure. Analysis showed that the addition of PCMs is beneficial in terms of improving thermal performance.

A significant drawback of PCM used in a passive ventilation system for heat recovery is the lack of instantaneous heat transfer across different airstreams. Phase change materials are a heat storage technology, whereby the heat is stored within the PCM until the air temperature has fallen to a significant level where it can be released back into the air stream. No research has been conducted into the use of PCMs between two airstreams of different temperatures where continuous, instantaneous heat transfer can occur. An investigation into this area would be beneficial for passive ventilation heat recovery research.<ref name=":2" />