Yukio Ishikawa

Division of Architecture, Graduate School of Engineering, MIE University, JAPAN
1577, Krima-machiya-cho, Tsu-city, Mie-prefecture, 514-8507, Japan
Corresponding Author, ishikawa@arch. mie-u. ac. jp

Abstract

The author has been investigating passive cooling systems in buildings with their environment controlled biomimetically and autonomously by simulating the physiological functions of animals and plants. The author directed his attention, making an attempt to apply it to evaporative cooling in buildings, to the perspiration function, one of the functions of heat dissipation of human bodies. A perspirable building with a perspiration function in its walls and roofs has been researched and developed. Those walls and roofs can absorb and desorb water autonomously, depending on their temperatures, water absorption below a certain specific sense — temperature, desorption above it. This paper describes the details of the perspirable building, development of the improved perspirable roof and experimental results of thermal performance of the roof. Further the seasonal passive cooling effects and energy saving effects are predicted by the theoretical simulation of room temperature and thermal load in a typical Japanese detached house perspirable. Also described are the areal optimum specific sense-temperatures of the perspirable roof.

Keywords: perspirable building, evaporative cooling, thermo-sensitive hydrogel, biomimetics

1. Introduction

There has been a growing tendency to attain a desirable living environment in buildings by energy saving and low global emission with the use of natural energy resources and natural environment.

Since we need both heating and cooling in Japan, it is necessary to investigate passive cooling in summer as well as passive heating in winter. From this viewpoint, the author has been investigating passive systems in buildings where the environment is controlled biomimetically and autonomously by simulating the physiological functions of plants and animals. As an energy saving building in the next generation, the building called as an environment-harmonized biomimetic building, has been developed, which simulates the environment physiology mechanism of a human body and other organisms. The human physiology mechanism such as perspiration, respiration, gooseflesh and shiver is simulated and applied to environment symbiosis and environment control in buildings. According to the concept, the building wall (roof and external wall) which can autonomously vary thermal insulation performance and the window which can autonomously vary the insolation shading performance, for example, were developed[1,2]. As one of the approaches, following the previous paper[3], this paper introduces research and development of a perspirable building which simulates heat dissipation by

perspiration as a thermo-control mechanism in the human body physiology. To begin with, an outline of a perspirable building is described, and the experimental result of thermal performance of the improved perspirable roof is shown. In addition, estimating the areal optimum specific sense temperature of the perspirable building by theoretical simulation, in which the autonomous perspiration (water absorption and desorption) of wall and roof becomes possible at a certain temperature (the specific sense temperature), the areal thermal effect of the autonomous perspirable building is shown, compared with the one of non-perspirable.