Low exergy building systems review

Low exergy building systems create more flexibility and generate new possibilities for the design of high performance buildings. Instead of maximizing the barrier between the building and the environment using thick walls containing large amounts of insulation, low exergy systems maximize the connection to the freely available dispersed energy in the environment. These connections to what we call "anergy sources" reduce exergy use and thus primary energy demand. This is achieved through the potential of new low temperature-lift ultra-high COP heat pumps. They achieve their low temperature-lift and subsequent high COP by providing low temperature heating with low exergy supply systems combined with a connection to a variety of technologies for capturing freely available renewable anergy sources. We present a review of these low exergy technologies being developed at the Chair of Building Systems at the ETH Zurich. These systems provide many methods for conditioning buildings using moderate supply temperatures and heat pumps that exploit more valuable anergy sources. This combination of low exergy systems maintains very low temperature-lifts, which can drastically increase heat pump performance from the typical COP range of 3-6 to values ranging from 8-15.