Articles
HEAT CONSERVATION IN GLASSHOUSES WITH ALUMINISED THERMAL SCREENS
Article number
76_40
Pages
275 – 278
Language
Abstract
Glasshouse compartments fitted with thermal screens of aluminised polythene and aluminised polyester laminated to clear polythene, both of which had high reflectivity to infra-red radiation required 55% less heat at a wind speed of 2 m/s than when not screened.
Under the reflective screens there was a 95% reduction in the radiation loss from the canopy of a tomato crop with a consequent increase in canopy temperature of 1°C; the influence of wind on heat loss from the glasshouse was reduced to a non significant level.
The screen reduced the rate of air leakage from the glasshouse by an average of 40%. The temperature of the reflective screen was usually above the dew point of the air beneath, so condensation on it rarely occurred.
The relative humidity under the screen was similar to a non-screened compartment until the crop was fully grown when it increased by 10–15%. Calculations show that use of a reflective thermal screen by a UK tomato grower could reduce heating costs by 40–45%.
Under the reflective screens there was a 95% reduction in the radiation loss from the canopy of a tomato crop with a consequent increase in canopy temperature of 1°C; the influence of wind on heat loss from the glasshouse was reduced to a non significant level.
The screen reduced the rate of air leakage from the glasshouse by an average of 40%. The temperature of the reflective screen was usually above the dew point of the air beneath, so condensation on it rarely occurred.
The relative humidity under the screen was similar to a non-screened compartment until the crop was fully grown when it increased by 10–15%. Calculations show that use of a reflective thermal screen by a UK tomato grower could reduce heating costs by 40–45%.
Authors
B. J. Bailey
Keywords
Online Articles (60)