Pilot study on the construction of several temperature-controlled multi-purpose rooms in a disused tunnel

Throughout the world, schemes for putting to use abandoned underground spaces are being pursued. We describe one such pilot scheme involving the utilization of a disused tunnel of an uncompleted railway line that has been revamped as a facility housing temperature-controlled multi-purpose rooms. In all, four rooms were constructed and installed with both indoor and outdoor air conditioning units. Testing of the facility was conducted over a 1-year period to establish operating criteria and to monitor for operating stability. The four rooms were finally maintained at different constant-temperature regimes: cold (5 °C), cool (13 °C), mild (21 °C), and warm (32 °C) with such low power consumption of 0.80 kW because of the nature of the subterranean site. Compared with typical surface facilities, this facility offers an obvious advantage in lower energy consumption. Monitoring of the humidity in the rooms revealed that preventing evaporation from the bare soil surface in the tunnel was the more important factor in controlling humidity in this facility.The heat transfer analysis of this facility was carried out through the computational analysis using a computational model constructed in this study. Computational analysis showed that the heat insulation property of the tunnel wall was reinforced by prolonged operation and the cost of operating facility became lower with the operation time. In addition, we demonstrated the procedure to estimate the overall heat transmission coefficients of the tunnel wall which was a great help in the design of similar facilities in underground spaces.The different rooms in the facility are expected to be used for manufacturing fermented foods and drinks depending on temperature and humidity requirements. Not only running costs but also initial costs are expected to be lower than those for surface facilities; for this reason, our system has been demonstrated to be economically viable as well as environment friendly.

► The successful operation of four constant temperature rooms in a tunnel with low power. ► The independence from outside seasonal temperature variations of each room. ► Easy humidity control by preventing surface evaporation in the rooms. ► Estimation of heat transfer in the underground facility by a computational analysis. ► Presentation of estimating procedure for suitable design of an underground facility.