Effect of covering materials on greenhouse energy consumption and microclimate, and on growth and development of stocks and snapdragons

The objective of the present study was to provide an extensive energy, microclimatic and agronomic assessment of single glass (GL) and several double anti-fog polyethylene (PE) cladded greenhouses. The effects of thermal screen (TS) and supplementary lighting under four covering materials on energy consumption and plant growth were also studied.;The outside layer of double inflated PE houses was standard PE. For the inside layers, anti-fog 1-year (AF1), anti-fog 3-year (AF3) and anti-fog thermal (AFT) PE films were installed for three identical compartments, respectively. All films were maintained for three years. The single glass cladding was always combined with the use of thermal screen during the night, while thermal screen in the PE houses was deployed two out of four weeks for comparing its effectiveness. There were two light regimes in each compartment: ambient and ambient + supplementary lighting. Supplementary lighting (60 ;From this three year study, we can conclude that the greenhouse covered with double polyethylene with AFT layer was the most effective in terms of energy savings (reduction of 11 to 23% in whole day energy consumption compared to GL + TS). The thermal properties of the greenhouse with an AF3 was similar to or slightly better than GL + TS. AF1 had a greater heat loss coefficient and showed a greater relative decrease in energy consumption due to a thermal screen than other PE cladded houses. This study also showed that the contribution of supplementary lighting to the total greenhouse heating demand is not negligible. The proportion of useful heat supplied by the lamps increased with the temperature difference between inside and outside air (;Among the PE materials, anti-fog 3-year film was the most transparent to PAR. PD in the double plastic houses was 0.2kPa lower than under GL in the winter season. The difference in RH between various anti-fog films was not significant. The use of a thermal screen in a double PE greenhouses caused no significant modification in greenhouse humidity. There was only a slight difference in the growth and development of stocks and snapdragons grown under single glass and double anti-fog PE coverings. (Abstract shortened by UMI.)...