Microclimate Fluctuations and Temperature Modelling of Naturally Ventilated Greenhouse Nurseries in Tropical Region

Abstract

Wood production from industrial plantations in Indonesia has increased from 18.8 to 49.6 million m³ (2015–2022). This requires an increase in the supply of seedlings in terms of both quantity and quality. Generally, seedling production involves the use of seeds and cuttings in greenhouses, followed by their relocation outdoors once they are nearly ready for planting. The success of greenhouse seedling production is often hampered by challenges related to temperature increases beyond the tolerance limits of the seedlings, which disrupts their growth. This study aims to identify temperature fluctuations inside greenhouses where Eucalyptus seeds are grown as a source for the pulp and paper industry and to develop a heat transfer model suitable for the conditions of these greenhouses. Climate conditions inside and outside the greenhouses were measured using automatic weather stations at 30-min intervals over five months. The developed heat transfer model explains how external climate changes affect the temperature inside the greenhouse. Based on the greenhouse conditions, differences in temperature between the floor and roof can be disregarded, resulting in a simpler heat transfer model. This model yields a coefficient of determination (R²) of 0.9051 and a root mean square error (RMSE) of 1.31°C. Temperature fluctuations inside the greenhouse are relatively more stable, with an average temperature 0.1°C lower and humidity 2.9% higher than those outside. A limitation of the model is its inability to accurately predict extreme outdoor temperatures. Therefore, this model requires further development, including considering the possibility of changes in heat transfer parameter values at more extreme temperatures.