The utilization of geothermal energy is constantly increasing for economic and environmental advantages that this brings. Use of horizontal ground-heat exchangers (GHEs) can reduce installation cost and compromise between efficiency and cost. Among many kinds of horizontal GHEs, slinky and spiral-coil-type GHEs show higher thermal efficiency. This paper presents the results of experiments on the heat exchange rates of horizontal slinky, spiral-coil and U-type GHEs installed in a steel box (5 m x 1 m x 1 m). A commercial dry sand was used to fill the steel box, and thermal response tests (TRTs) were conducted for 30 h to evaluate heat-exchange rates according to various GHE-types. The U-type GHE showed the highest heat exchange rate per pipe length, about two and two and half times higher thermal efficiency than that for the horizontal slinky and spiral-coil-type GHEs, respectively. Furthermore, the heat exchange rates per pipe length with a relatively long pitch interval (pitch/diameter = 1) were 100-150% higher than those with a relatively short pitch interval (pitch/diameter = 0.2), in both spiral-coil and horizontal slinky-type GHEs. A cost-efficiency analysis was also performed, and it revealed that the U-type GHE was most economical under conditions of providing equivalent thermal performance. (C) 2015 Elsevier B.V. All rights reserved.