Earth-Tube System to Control Indoor Thermal Environment in Residential Buildings

Abstract

Earth-Tube systems are used in residential buildings as a passive heating & cooling technique to reduce the over-all active energy utilization in buildings. The Earth-Tube systems tend to warm up the residential buildings during winter & cool them down in summer, using the temperature difference phenomenon between the atmosphere and beneath the earth surface. Seasonal variations in temperature drop off with depth and disappear below 4 to 5 m due to thermal inertia. This research through experimental study, explored the use of earth–air heat exchanger (EAHE) system in an economic way to control indoor air temperature by using local materials. An EAHE was built near the meeting room of Department of Architectural Engineering and Design, University of Engineering & Technology, Lahore, Pakistan. Outdoor and indoor day-time temperature was recorded for seven days in the month of May and June. On average, system was able bring the indoor temperature to 30oC as compared 40oC outdoor. Efficiency of EAHE system was determined as 88% which can be considered as more than acceptable. Payback period analysis was conducted on the data based on cooling the room with air-conditioning alone and with air-conditioning and EAHE system together. It was found that the EAHE system will payback its installation amount in less than six years through electricity saving. The research is highly significant keeping in view Pakistan’s severe energy crises and environmental issues arising from fossil fuels to produce electricity. The research finding will be helpful to introduce a cost effective environmentally friendly non-hazardous tubing system and will provide necessary guideline for Architect and Engineers to implement this passive thermal controlling technique in residential entities.