Contrary to heat pipes, plate heat exchangers (recuperators) and rotary heat exchanger (regenerator) no junction of the air flows is required at the bildings energy recovery system for coil energy recovery loop systems. Through the absolute separation of extract air flow and outdoor air flow the coil energy recovery loop system is the firs choice for buildings with high hygienic demands. As the several heat exchangers are connected to each other by a heat transfer fluid (brine), feed-in and feed-out of thermal energy in the coil energy recovery loop system is possible.