PLEA2006 - The 23rd Conference on Passive and Low Energy Architecture, Geneva, Switzerland, 6-8 September 2006
To create adequate conditions under high humidity levels, external temperatures requires to be decreased, and to be promoted internal air flow. Also the thermal inertia needs to be controlled specially during the afternoon.
3. BIOCLIMATIC STRATEGIES
3.1 Architectural Layout.
The entire building has 50.000 m2 distributed into three commercial levels, and two underground parking areas. The pedestrian corridors, plazas and café terraces are designed to be naturally cooled. Shops are supposed to solve their comfort needs using mechanical or air conditioned systems.
The commercial levels are connected vertically by open atriums, which include stairways and elevators. The centre is oriented east-west according to the urban and plot conditions.
In order to promote internal air flow, the building takes external air directly from open main entrances and open facades placed at café terraces (oriented facing to prevailing S.W winds). Additional air supply comes from underground pipes, using a vacuum pump to pull down air from the street level and releasing it at the bottom level - 1st floor. In the other hand, four high atrium areas make possible a high stratification of internal air mass. The curved roof and the wind skylights, promote the stack effect and heat release by convection forces. To control direct solar radiation coming from the west during the afternoon, were designed suspended metallic sunshades which are placed above the entrances. Also there are close exterior walls without openings. To control heat transmission trough the envelope, a double naturally ventilated hollow brick façade was created. To prevent direct heat gains by horizontal solar radiation at noon, there is a roof composed with double white metallic sheet ( sandwich deck) using as insulation a 5cm of mineral wool above strategies are illustrated in figure 2.
Figure 3: North- west main facades
4. COOLING RESULTS
Actually the entire core structure has been finished, including the external and internal walls, floors and the roof. Finishing details as solar shading devises, underground pipes, and sky roof ventilation blades will be installed during May 2006. Nevertheless, preliminary test results show the efficiency of the envelope and its internal main spaces as the atria, corridors and double facade space. The monitoring process was carried out during a special hot and humid day of March 2006. The monitoring tests focused on three cooling results:
The effect of atria and ventilated sky lights on internal air stratification levels.
The combined effect of ventilated sky lights and insulated roof in the diminution of maximum external temperatures.
The effect of the naturally ventilated double facade in the radiant internal temperatures
The figure No 4 shows the internal profile of humidity, indoor temperatures at the three main levels, and outdoor temperatures.
temperatue /humidity 22 /3/06
temp oC/RH %
1st floor interior temp
2st floor interior temp 3
st floor relative
Figure 4: Temperature and humidity measurements