Thermal characteristics of screenhouse configurations in a West-African tropical climate.

Raghavan, G. (Supervisor) The Biological Control Program (BCP) for Africa operates from Cotonou, Benin, which is part of the International Institute of Tropical Agriculture (IITA). Its present mandate includes the provision of Biological Control Labs to African National Biological Control Programs. Thirty tropical countries are targeted. The challenge presently faced by the BCP is to develop biological control structures adapted to the climatic and economic conditions of those countries. Specifically, structures such as greenhouses, screenhouses and growth chambers must provide, at reasonable expense, protection of experimental material against insects and airborne pathogens, as well as close to ambient temperature and sunlight. A recent innovation, the "screenhouse", is a promising technology with respect to its inherent capacity of providing near-ambient conditions by passive cooling (natural ventilation, radiation absorption and evaporative cooling) alone. However, overheating is still a problem in many conditions. In order to characterize the thermal performance of such structures, and to optimize their cooling performances, various screenhouse architectural configurations, screen types and water cooling options were evaluated during three seasons at the IITA, BCP research station. Le Programme de lutte biologique (PLB) pour l'Afrique de l'Institut international d'agriculture tropicale (IITA), base a Cotonou (Benin), a notamment pour mandat de fournir des laboratoires de recherche sur la lutte biologique aux programmes nationaux de lutte biologique des pays africains. Trente pays tropicaux sont vises. A l'heure actuelle, le PLB est confronte au défi du développement de structures de lutte biologique adaptées aux conditions climatiques et économiques de ces pays. Plus précisément, les structures telles que les serres, les serres grillagées et les chambres de croissance doivent protéger, à des coûts raisonnables, le materiel experimental contre les insectes et les pathogènes véhiculés par l'air, tout en présentant des temperatures proches de la temperature ambiante et tout en laissant passer les rayons du soleil. La nouvelle technologie des "serres grillagées" semble prometteuse en ce qu'elle fournit des conditions proches des conditions ambiantes grace au refroidissement passif (ventilation naturelle, absorption des radiations et évapotranspiration). Cependant, la surchauffe reste un problème dans de nombreuses conditions.