dc.description.abstract | Abstract Greenhouse is commonly used to protect plants from unexpected weather condition. In this research, natural ventilation's rate in a single span greenhouse owned by Faculty of Agriculture at Cikabayan IPB has been measured. Theoretical equations is used for this research's method to find the natural ventilation's rate than the findings are verified. This research also evaluated the block plan design. Temperature, humidity, wind velocity and direction, solar radiation, air pressure's data are measured using a weather station at two greenhouses building. The data were processed by a computer program using visual basic language. This research found that the neutral plane is located at 3, 5 meter up from greenhouse's floor; it means that these greenhouse's side walls are only functioned as an air inlet. It is found that in a wind speed >2 m/s, either in low radiation (<500 w/m2) and high radiation (> 500 W/m ), the natural ventilation's rate is very fluctuated inside the two greenhouses. This shows that the ventilation system has not been appropriate yet. Between the calculated and the measured natural ventilation's rate show an error not more than 30%, it means that the develop equation can be used to predict the natural ventilation rate inside a single span greenhouse. The micro climate inside greenhouse I and I1 are equal. It means that greenhouse's lay out has already been appropriate. | id |