The study on the low-loaded cooling of well insulated houses in the warm-temperature regions

2004 Fiscal Year Final Research Report Summary

• Project/Area Number: 15560514
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Architectural environment/equipment
• Research Institution: Hokkaido Institute of Technology
• Principal Investigator: SUZUKI Kenzo Hokkaido Institute of Technology, Department of Architecture, Professor, 工学部, 教授 (70002235)
• Project Period (FY): 2003 – 2004
• Keywords: air conditioner / cooling / well insulated house / energy conservation / cooling room temperature / Coefficient of performance / inverter control / unsteady analysis program

Research Abstract

I have surveyed air conditioner operating conditions and indoor environment of houses in relation to their thermal insulation performance in Kansai (Kyoto, Kobe city), Tohoku (Aizu-wakamatsu city) and Hokkaido (Kitami city). In Aizu-wakamatsu and Kitami, air conditioners were used since morning when ambient temperature exceeded 25℃, and the average room temperature was 26〜27゜C. In Kyoto and Kobe, however, the utilization of air conditioners in the daytime was little, and they were used only during the period between the evening and pre-sleep time, and the average room temperature was 28〜30℃. The difference in such utilization by the thermal insulation performance was small because people in Kansai lived in their houses with their windows opened. They had the impression that high-insulated houses kept in the heat due to their insufficient ventilation performance even if a maximum room temperature was low.. In Kyoto and Kobe, habituation for a heat and apprehensions on the health concern ing air conditioner use, discomfort of top and bottom temperature gradient have reduced the utilization of air conditioners.
In Aizu-wakamatsu, air conditioners frequently repeated the on/off operation when each air conditioner in all rooms was utilized at the same time since such use resulted in the excessive capacity of electricity and exceeded the range of the inverter control.
I confirmed such air conditioner on/off operation leaded to the extreme drop in efficiency by the experiment. However, the on/off operation did not occur in Kitami since it has been air-cooled by 1 air conditioner in all rooms. From the viewpoint of its efficiency, it is desirable that a high thermal insulation house install an air conditioner in second floor hall etc. and it continuously keep the room temperature.
I developed "Room temperature and load fluctuation analysis program" in which the accuracy of the calculation of the external wall with vent layers was improved. It was clarified that adopting a higher thermal insulation performance than that defined in the energy saving standard to houses in warmer areas also resulted in period cooling load decrease.