earth-to-air heat exchangers

The energy efficiency and energy consumption of mechanical ventilation systems depend mainly on the heat and cool recovery efficiency and the operational costs of electric energy for air handling unit fans.

For free pre-heating of fresh air in winter and pre-cooling in summer and to protect the heat exchanger in the air handling unit against freezing earth-to-air heat exchangers (EAHEs) are used. For large demand of fresh air multi-pipe systems are used to diminish total pressure losses and provide required amount of thermal energy.

This study presents some results from a monitoring project with night ventilation and earthto- air heat exchanger. Both techniques refer to air-based low-energy cooling. As these technologies are limited to specific boundary conditions (e.g. moderate summer climate, low temperatures during night, or low ground temperatures, respectively), water-based low energy cooling may be preferred in many projects. A comparison of the night-ventilated building with a ground-cooled building shows major differences in both concepts.