Indoor environmental quality and workers’ productivity in electricity-saving offices –through the experience of the Great East Japan earthquake in 2011

Owing to the enormous damage caused by the Great East Japan Earthquake of 2011, electricity-saving measures are promoted in offices today for both environmental and safety reasons. This paper aims to reveal how much indoor environmental quality (IEQ) has changed, and the extent to which this change impacted subjective evaluations of IEQ and productivity. The authors have conducted continuous fieldwork and questionnaire surveys in seven electricity-saving office buildings in the summers of 2011–2013. The results show that excessive indoor air temperature, such as 28^oC, was avoided; however, indoor air quality did not change significantly. On the other hand, desk-level illuminance greatly decreased, from 750lux to around 400lux, after the earthquake. Moreover, the average change rate for self-estimated productivity improved from -6.6% during the earthquake year to almost 0% after the earthquake. People learned to implement electricity-saving measures in a proper way that did not spoil workers’ comfort and productivity. Furthermore, we calculated the importance of each of the environmental satisfaction metrics for the integration of environmental satisfaction by using post-earthquake data. The result shows that thermal environment and indoor air quality should be improved preferentially. We need to create energy-friendly and worker-friendly office environments based on these results.