The Hygrothermal Environment and Potential for Mold Growth within a Straw Bale Wall

Abstract

The present study is the first investigation in Japan to monitor the interstitial hygrothermal environment of a straw bale wall at various depths and heights. Extensive interstitial monitoring has been conducted on a straw bale building in Kyotango City, Kyoto Prefecture known as "Shinrinnobokujo-tango". The purpose of the present study is three-fold: (1) Determine if the interstitial hygrothermal environment of Shinrinnobokujo-tango's south straw bale wall is homogenous, (2) elucidate the interstitial hygrothermal environment of the south wall, and (3) evaluate the potential for mold growth. As a result of the study, the interstitial hygrothermal environment was found to vary by height and depth. In winter, the interstitial area with the lowest temperature and highest relative humidity was the upper, exterior portion of the wall. In summer, the area with the lowest temperature and highest relative humidity was the lower, interior portion of the wall. Mold growth was predicted within the straw bale wall, with the greatest risk being the upper, exterior portion of the wall in winter and lower, interior portion of the wall in summer. These results suggest the need to control moisture in straw bale walls in Japan.