The objective of this work is to understand and successfully control the phenomena found at the openings when the enclosure is subjected to a linear heat source. The enclosure is not adiabatic. The control and understanding of its phenomena will be carried out by differential static pressure measurements. These measurements were carried out in calm weather using a Furness control micro-manometer in 20 points at positions x+ = 0, y+ = -0.5 and along the vertical z+. We have studied four enclosure configurations. Each configuration has two or four or six openings. The openings have identical characteristics, height h = 34 mm and width l = 210 mm. The height of the enclosure is H = 520 mm and the length is equal to the width L = l = 210 mm. We have shown the influences of the reduced Grashof number (Gr*), the number and the position of the openings on the differential static pressure with and without dimension and compared the experimental results obtained with those of cases 11 and 12 of Koueni Toko (2019). It appears that the values and forms of the static pressure and the values of the neutral height can vary according to Gr* and number and the position of the openings.