ソーラーチムニーと地中ピットとを組み合わせた自然換気システムの性能に関する4年間の実測調査: 第1報-システムの運用状況と自然換気作用時の給排気風量

摘要

北九州市の大学校舎建築に導入されたソーラーチムニーと地中ピットとを組み合わせた自然換気システムを対象とし，運用下におけるその性能を把握することを目的として開校後4年間に渡って実施した実測調査の結果を述べる．本報では実測対象建物の自然換気システムと補助空調システムの概要，本システムの運用状況，自然換気rn作用時の給排気風量の実測結果について報告する．自然換気が作用する時間は開校3年目まで増え続け，2年目から4年目の自然換気作用時間は冷房期間の33～61％を占めた．自然換気作用時間の80％程度が夜間であった．自然換気作用時の給排気風量は，年間の全時間平均で，地中ピットからの給気量は6,000m~3/h程度，ソーラーチムニーからの排気量は4,000m~3/h程度であり，4年間を通してほぼ安定していた．この差は主に排気フアンによる影響であり，ソーラーチムニーからの排気量は風量の多い便所排気フアンの運転停止に左右されていた．給排気風量は，中間期に増加し，夏期に減少する傾向が見られた．%The specific features of the natural ventilation system combined with solar chimney and underground pit installed in the new university buildings in Kitakyushu City are described together with the measured results of supply/exhaust air volumes, when the natural ventilation took place, for four years after the school opening. The period of natural ventilation increased to cover 33-61% of the cooling period from 2nd to 4th year, being amounted to 80% at night hours for four years. During the period of natural ventilation, the supply air volume through underground pit to the occupied spaces was found about 6,000 m~3/h and the exhaust air volume from the occupied space to solar chimney about 4,000 m~3/h on annual average, beingrnquite stable for four years. The rate of supply and exhaust air volumes through the grilles installed between the corridors and the vertical shafts were estimated from the air velocity across the grilles measured by the special device developed for this purpose. It was found that the exhaust volume from the occupied space to the solar chimney shaft and that from the solar chimney to the outside air were coincided as a whole. The tendency of supply/exhaust air volumes was found to increase in the intermediate seasons and decrease in summer. Exhaust air volume from solar chimney was affected by the operation mode of toilet exhaust fan with a rather large air volume to a considerable extent. The maximum amount of air change rate by natural ventilation based on outside air intake volume through the underground pit was estimated to 1.3 h~(-1) during the daytime and 1.0 h~(-1) during night time while the toilet fan operating.