Passive ventilation system that incorporates a pitched roof constructed ofbreathing walls for use in a passive solar house

This paper describes a natural ventilation system that incorporates a pitch ed roof constructed of Breathing Walls for use in a passive solar house. Th e Breathing Wall is expected to solve the inherent contradiction that exist s for a building that is open to the outside air, in which a balance in the indoor air/moisture conditions is maintained, but energy efficiency is low . In other words, the use of Breathing Walls can provide a healthy and comf ortable environment at higher energy efficiency in a passive solar house. I n the present study, we experimentally evaluate the effects of roof pitch a n the heat recovery capability and the occurrence of internal condensation within the Breathing Wall, using a simulation of the ventilation rate of a natural ventilation system. The effective opening area per unit area requir ed to provide sufficient air change capability, i.e., 0.5 AGH, even for zer o wind velocity, was determined to be 10 and 5 cm(2)/m(2) for pitches of 26 .5 degrees (Pitch 1) and 45 degrees (Pitch 2), respectively. Furthermore, a t the maximum predicted wind velocity of 10 m/s for Pitch 1/2, even though the outdoor air temperature is 5 degrees C, the temperature of the indoor-m ost air reaches 13.2/12.5 degrees C, corresponding to a heat flux of;approx imate to 128/158 W/m(2). No internal condensation occurs, even at the maxim um pressure differential, which corresponds to a wind velocity of 10 m/s ac ross the wall of the Pitch 1/2 model, when a Breathing Wall having an openi ng area per unit area of 11.3 cm(2)/m(2) was installed in the ventilation s ystem. (C) 1998 Elsevier Science Ltd. All rights reserved.