JAUE2012-025: Basic Analysis of Soil Temperature Data Archives for the Use of Geothermal Energy

Abstract

Realizing a low-carbon society is our urgent necessity. In order to achieve this goal, in our branch of architecture dealing with a way of using energy, challenges are required to convert to use the renewable resources. Our aim is to establish a simple and easy prediction method for architects to estimate a prospective amount of geothermal energy. We found a collection of underground temperatures archives, which is compiled by Ministry of Agriculture, Forestry and Fisheries (MAFF) and Japan Meteorological Agent (JMA) in 1982. With this database (recorded 1932-1948), we reexamined hypotheses about underground temperature. We confirmed the followings.
- We could not find isothermal layer among 0 - 5 meters depth.
- Underground temperature was the deeper, the smaller in annual variation.
- The averages of underground temperature at each depth at each observatory were almost equal (average difference was 0.9 degrees).
- The delays of peak temperature appearance at 5 meters depth in comparison with the surface layer were 3.3 months in average.
- Average annual underground temperatures were higher than Average annual air temperatures (The differences was 1.7 degrees in average).