| Summary: | There is global effort to reduce the emission of greenhouse gases that causes global climate change, of which significant percentage is related to buildings. Uses of passive and low-energy strategies for indoor thermal environmental control are being explored by researchers to reduce the operational energy consumption in bUildings. One of these options is the use of thermal mass of the ground as a heat source or heat sink for cooling and heating of indoor spaces in bUildings. Earth-air heat exchanger (EAHX) is a subterranean ventilation system that can be used to pre-coollpre-heat building ventilation air supply. Due to the ground's thermal mass, the daily fluctuation of ambient extremes is dampened with increasing depth below the ground surface. Therefore soil temperature at 1 m depth and below is always lower than ambient temperature in summer and higher than ambient temperature in winter. The application of EAHX and knowledge of their performance is scarce under UK climatic and soil conditions. This research therefore aims to evaluate the potential of using EAHX in the UK for cooling buildings in summer. Critical literature review has been undertaken on the performance of EAHX in different climatic conditions and the various approaches to the thermal analysis of EAHX. It reveals that the system has potential for building cooling applications in a variety of conditions. A standalone simulation tool has been developed using the Transient System Simulation Environment (TRNSYS). Building models using different mechanical ventilation strategy have also been developed to enable integrated evaluation of the performance of EAHX on indoor thermal comfort conditions and building cooling loads. Data of climatic and soil parameters required for the thermal analysis of EAHX have been determined for different regions in the UK. Integrated thermal simulations of EAHX system have been conducted using the developed building models and the determined soil and climate conditions. Monitoring data from an existing project incorporating EAHX have been analysed and results have been discussed. Parametric study of EAHX has been carried out for three locations, representing the regional climate span of the UK, in order to evaluate the range of thermal performance of the system. Data of various performance indicators have been established to provide the necessary information for the evaluation of the system potential in different locations. This research has established the thermal performance and the characteristics of the important parameters for the design of EAHX system in the UK. The outcomes are significant in contributing to a better understanding of the system's thermal behaviour and in predicting the thermal performance for building cooling application. As a future work, based upon the data generated by this research, there is a need to develop a full database of the performance data for different configurations of EAHX and at different locations around the country. There is also a need for integrated design tool to evaluate the dynamic thermal performance of EAHX system when integrated with other ventilation strategies.
|
|---|
