Measurements and modelling of an earth-to-air heat exchanger for retail building ventilation

An earth-to-air pipe type heat exchanger (EAHE) is a simple and effective ventilation system component, used for preconditioning of the fresh air supplied to a building. This paper presents two sets of results of operational parameters long-term measurements and energy analysis of EAHEs, located under two different retail buildings of floor area over 1000 square meters each.  
In the second part of this paper there is described the mathematical model of the EAHE operating in a mechanical ventilation system of a retail building implementation into computer code, written in MS Excel and used for simulation of EAHE long-term operation (i.e. at least one year). The thermo-hydraulic phenomena inside the EAHE are simulated, as well as the calculation of transient three-dimensional (3-D) ground temperature field is performed with use of the method of elementary balances, in an open schema. 
The elaborated model allows to analyse the impact of control strategy of ventilation system on the energy efficiency of this exchanger. As a result of this investigation, the control algorithms in described real facilities were found to be not optimal. Changes in the control strategy, leading to improvement of energy efficiency of EAHE and ventilation system in the same way, were proposed.