The discussion about the appropriateness of underground spaces for office use has been intensified during the past few decades due to the problem of growing population density and rising land prices, especially in Japan. However, the human reactions towards underground spaces as working environment are not yet well understood. Furthermore, most of the previous studies have been carried out in western countries.

The present study was a qualitative analysis of underground and above ground office employees' conceptualization of office environments. First, existing literature in the area is reviewed,presenting previous research both for and against underground work places. The empirical study consisted of interviews with 10 employees, and a multiple sorting task comprising 48 employees (25 employees in the underground and 23 employees in the above ground office).

The results of the free sort showed that the conceptual systems of both the underground and above ground workers were rather similar.The conceptual systems of employees in both conditions formed four major groups: work related, window and atmosphere related,temperature related and negative aspects.

However, the results of the instructed sort into essential, hindering and neutral aspects of the work environment showed a clear difference between the underground and above ground employees. According to the conceptual systems of the underground subjects, a fourth region, comprising concepts relating to windows, emerged apart from the three instructed groups. This is believed to be the result of the underground workers' awareness of being underground and lacking windows, thus resulting in a more concentrated thinking about windows, or a more accentuated wish for them.

It is, therefore, concluded, that windows should be provided in work places, thus the use of underground and windowless spaces for offices should be avoided.