Vitaly Haslavsky  -  Azrieli College of Engineering 26 Yaakov Shreibom Street, Jerusalem, Israel .

The overall heat transfer coefficient of thermal screens is evaluated. Such screens are applied to improve the performance of combined heating/cooling and dehumidification system, invented by Avraham Arbel and mutually developed with DryGair Energies Ltd., providing the desired conditions in closed greenhouse. By significantly reducing fossil energy consumption, this design contributes to sustainability as well. Reduction of heat loss or gain is achieved by using several layers of thermal screens. In this work, a hot box methodology to measure heat flux through multi-layers insulation materials is implemented, while considering different types of thermal screens and their integration with greenhouse covers to estimate the overall heat transfer coefficient. The results indicate that with only one layer, the heat transfer coefficient is reduced by around 70% compared to covers without screens, while the contribution of additional layers may increase the performance to about 90%