Evaluation of comfort of low-temperature local airflow during natural ventilation and its application to air-conditioning using airflow

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14888
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 23020:Architectural environment and building equipment-related
• Research Institution: Tokyo Polytechnic University
• Principal Investigator: YAMAMOTO Yoshihide 東京工芸大学, 工学部, 准教授 (50823738)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 自然換気 / サーマルマネキン / 非等温気流 / 気流活用空調

Outline of Final Research Achievements

The purpose of this study is to clarify the relationship between local non-isothermal airflow and thermal comfort, assuming natural ventilation. Experiments in an active-controlled multi-fan artificial climate chamber have determined multiple low-temperature and local airflow patterns that reproduce the indoor airflow environment during natural ventilation. Furthermore, we measured the heat loss of the human body using a thermal manikin and proposed a formula for estimating the heat loss of the human body.
In the subject experiment, thermal comfort during local airflow exposure was investigated. Because of local airflow, even at a room temperature of 22℃, subjects reported feeling cold and uncomfortable. Conversely, even when the room temperature was 28℃ or higher, the comfort side was reported. Using these results, we presented a chart showing the room temperature comfort range when local airflow is generated in airflow-utilizing air conditioning.

Free Research Field

建築環境工学

Academic Significance and Societal Importance of the Research Achievements

自然換気システムはBCP対策やZEB実現を目指す非住宅建築物において近年積極的に採用され、自然風の気流感による快適性向上も期待されている。しかし、機械空調を前提とした現代の建物においては自然換気システムの省エネルギー効果が十分に発揮されていない事例も確認されている。自然換気による省エネルギー効果を最大化するには取り入れ外気の温度を可能な限り低くすることが望ましいが、低温の気流が換気口に近い居住者への不快感に繋がり、運用停止に至る事例も複数見られる。そこで、本研究では、自然換気システムの持続的活用に向けて、自然換気口からの局所的な低温気流と温熱快適性の関係について明らかにすることを目的とした。