PLEA2006 - The 23rd Conference on Passive and Low Energy Architecture, Geneva, Switzerland, 6-8 September 2006
Passive cooling for complex buildings in a humid tropical area- Study case Colombia
Agustin Adarve G Arch
Professional consultant, Adarve Arq, Bogota, Colombia
ABSTRACT: The presented case study relates to a naturally ventilated complex commercial building located in Colombia. The goals of this project are: a balanced integration between architectural features, bioclimatic requirements, cost-benefice relations and constructive needs. The strategies involved are: 1) The use of a combined stack and horizontal flow pattern in order to produce a high level of heat release at maximum interior air speeds. 2) The integration of a double envelope hollow brick façade to promote an effective solar control and radiant gains trough the interior building. The use of 14 solar towers help to exhaust heat, avoiding heat transfer to the internal concrete structure, producing an effective control of the thermal inertia. 3) The improvement of shading devices to avoid that direct solar gains go into open spaces (commercial main malls, meal spaces etc.) 4) The use of adequate insulating materials specially on the roof, in order to decrease interior temperatures due to solar radiation transfer at mid day. To achieve the requirements, some creative or “innovative” strategies were designed: These strategies include the use of “ventilated sky lights” (operating as wind towers) at the top of the roof, combined to a fresh air exchanger at the basement, to increase the temperature difference.
Keywords: natural cooling, tropical architecture, comfort
In Colombia, as in many tropical countries, passive cooling for complex buildings needs to be carefully integrated to the architecture if we want to solve comfort needs into an economical, technical and aesthetical way.
The commercial building Unicentro- Villavicencio is an example in the improvement of different cooling devises able to allow thermal comfort.
This paper presents the bioclimatic strategies, cooling results, conclusions and recommendations to take into account for a similar design process in developing countries located in humid tropical areas. The strategies that were used take special care of the local climate factors regard comfort stress, building specific needs, such as ventilation openings, solar and thermal control devises.
After monitoring the core building, the results shows some conclusions to be discussed forward:
Vertical air flow is essential to assure effective air movement, if the height of the open atrium produces a good heat stratification.
The convection flows produced by a good stratification have a better performance if ventilated sky lights are placed directly in the top of the mall atrium.
When there are no sky lights, a good insulated and reflective roof produces expected results.
Double facade walls are essential to control mass inertia, so that the interior walls temperatures remain lower.
The adopted cooling strategies guarantee structure and insulation economies, because it does not represent additional building costs. In addition, ventilated sky lights offer natural day lighting.
Villavicencio is a provincial capital located at 4 °N latitude, on the eastern planes between Colombia and Venezuela. It represents a typical hot humid area with external temperatures and humidity pattern away from de comfort zone during the day.
Figure 1: climatic data- over heated period (grey). R.M Aynsley  adjusts the comfort zone range between 24 °C – 30 °C at latitudes less than 30 °.