Takao Sawachi, Shigeki Nishizawa, Hiromi Habara and Hisashi Miura
Bibliographic info:
The International Journal of Ventilation, Vol. 7 N°2, September 2008

The effectiveness of various methods for saving energy and improving the indoor environment in buildings depends upon the building conditions under which those methods are applied. To find better design solutions in such situations, designers or building owners need to make reference to quantitative information so that they can choose appropriate methods, which fit to the design conditions. These include data such as climate, surrounding environment, construction, occupants lifestyle and economic constraints. Passive cooling by natural ventilation is one of the promising methods to achieve thermal comfort, but its effectiveness should be clarified, especially in relation to saving energy. In this paper, an integration of research outputs on cross ventilation is made in order to determine the reduction of cooling energy that can be achieved. This is undertaken by considering a series of questions and, by reviewing existing knowledge, finding appropriate answers. Existing research outputs include the prediction of wind pressure and discharge coefficients as well as the behavioural model of window opening by occupants, the application of coupled heat and airflow simulation tools, and the actual energy efficiency of air conditioners under use. Through such integration it is possible to estimate the sensitivity of cooling energy resulting from errors in the discharge coefficient and the wind pressure coefficient and to determine the necessary accuracy for those two parameters.