The Great East Japan Earthquake and Tsunami which occurred on March 11, 2011 caused widespread damage and electricity shortage. So the Japanese government has directed large-scale electricity users to curb their consumption by 15 percent of what they used last summer. However, excessive saving electricity forces office workers to be patient, and it can lead to productivity decline. In this study, the field survey and questionnaire survey were conducted in six buildings saving on electricity to study the indoor environment, the workers' productivity and energy conservation. As a result, it was found that the rise of temperature leads to the sharp decline of productivity and comfort, and that power saving of lighting made less dissatisfaction for office workers and reduced more electric energy than turning up the air conditioning. Office workers can keep productivity if there are no dissatisfactions for them. Therefore, lowering illuminance is found to be more effective for saving electricity than turning up the air conditioning.
