Recently, issues for environmentally friendly architecture and energy reduction have also been raised. Currently there are various regulations on energy consumption in different countries all over the world. There are still difficulties in dealing with problems associated with increasing energy demand, especially those during peak electricity demand. To solve these problems, technologies enabling the application of new renewable energy have been emerged. Of them, geothermal heat pumping system has been expected to realize an effective saving in heating and cooling energy because it would exploit the geothermal power that is stable all year round. However, comparatively high cost associated with the installation of such facilities and limited sites for such installation have slowed the propagation of such facilities, especially, in small-size buildings. Therefore, it is necessary to develop small-size ground heat exchanger with low cost and quick installation. Therefore, in this research, in order to reduce the initial cost, the unit-type ground heat exchanger was developed. In this paper, the system performance according to design factor was analyzed by the integrated simulation with ground heat transfer model, ground heat exchanger model and ground surface heat flux model. In addition the verification experiment was performed based on simulation results, possibility of introduction were analyzed through the comparison conventional vertical closed loop system with Initial cost. This paper of the contents of this study are as follows.
? As a result of heat extraction according to pipe distance of underground heat exchanger and distance of heat exchanger, it was confirmed that the distance of heat exchanger had greater influence on the heat exchange rate rather than the pipe distance of ground heat exchanger.
? The effect of installation depth was analyzed. Result of the analysis showed the difference about 19% in heat exchange rate according to installation depth.
? As the results of characteristic of heat extraction according to grouting materials, using Cement - Silica sand - Graphite(case 3) showed 16% higher performance of heat exchange than using Bentonite - Silica sand - Graphite (case 2).
? As the results of characteristic of heat extraction according to pipe diameter of underground heat exchanger and distance of heat exchanger, the heat exchanger rate per unit length increases up to around 40% as heat exchanger rate per unit length is longer and around 62% as pipe diameter is bigger in same soil condition.
? In the result of verification experiment, COP of cooling experiment was 5.47 and experiment of heating was 4.13.
? In the result of economic assessment, it shows a about 45% saving effect on construction cost compared with the vertical closed loop heat exchanger system.