昼光変動緩和のための人工照明調節方式に関する検討（その１）：昼光変動に対する生活者の意識と照度変化に対する評価

<p> The co-use of daylight and artificial lighting is important from the perspective of reducing energy consumption. However, as the illuminance in a room frequently changes when only using daylight, this may cause habitants to feel inconvenience when carrying out daily activities. In this report, we implemented a questionnaire on daylight fluctuations in rooms, actual measurement of the daylight fluctuations, and an impression evaluation under the environment where illuminance change, to investigate the necessity of illuminance control for temporary fluctuations in daylight in rooms.</p><p> From the questionnaire results, it is considered that many people want to actively use daylighting, and are, in fact, using it, but a large majority of them have felt discomfort regarding the fluctuations and brightness in daylight. 74% of people have noticed daylight fluctuations, and 40% of them have felt discomfort with daylight being too bright and in regard to fluctuations in illumination. In addition, some people feel discomfort with automatic dimming of artificial illumination.</p><p> Measurement of daylight illuminance was conducted for 8 days on August and September 2014. Global illuminance, illuminance from unobstructed sky, and horizontal illuminance in a room were measured for 1-second intervals. The cumulative relative appearance frequency of illuminance change ratio from 0.83 to 1.20 is 88.9%, and that 0.67 or less or 1.50 or greater is 2.3%. The illuminance change continuation time at 80 minutes or longer exists, however cases at 2 seconds or shorter share 32.9 %.</p><p> We grasp the ratio of discomfort in relation to temporal illuminance changes in a room where the light environment only monotonically increases or decreases using the subject of an experiment. In such space, we implement the illuminance change ratio by 0.71 or less or 1.41 or greater, which deems to be a comparatively large change for daylight fluctuation. The larger the illuminance change ratio increases, the greater the ratio of discomfort increases, as the change continuation time increases, the lower the discomfort ratio decreases. Additionally, when the illuminance level increases, if the illuminance level is high before the change, the discomfort ratio is high, whereas if the illuminance decreases and the illuminance level were high before the change, the discomfort ratio is low. The discomfort ratio in regard to temporal illuminance fluctuations with a change continuation time of 8 seconds and illumination change ratio of 2 times or 0.50 times was 5.3-58%. Most of these figures are lower than the questionnaire results about cases in which discomfort was felt with the fluctuation.</p><p> From these a questionnaire, actual measurement, and an impression evaluation, it was shown that as even if the appearance ratio is low, discomfort occurs in relation to comparatively large daylight fluctuations, controlling to mitigate fluctuations in the illuminance due to daylight may contribute to the quality of the lighted space. Further, we will clarify, how workability and atmosphere are evaluated when illuminance changes in addition to discomfort concerning temporal illuminance change. Furthermore, assuming cases when illuminance is supplemented with artificial lighting to maintain fixed level of illuminance on a desk by daylighting, we will clarify the impression of a room when adjusting the illuminance using artificial lighting.</p>