Investigation of the potential of long wave radiation heating to reduce energy consumption for greenhouse heating

Abstract

A parametric study has been carried out to quantify the contribution of each of the components of a greenhouse to the energy consumption during heating. The greenhouse, located in Western Greece, is heated by water pipes. Steady-state thermal balances are developed under general heating conditions and an approximate expression to estimate heating efficiency is introduced. The results confirm the dominant contribution of convective and radiative heat losses through the greenhouse cover. For the present case study the estimated heating efficiency coefficient does not exceed 17%. Thermal performance of the same greenhouse by assuming direct heating of the plants by long wave radiation is achieved by exploiting the general formulations of the thermal problem developed. A significant potential for increasing heating efficiency by involving long wave radiation heating is demonstrated. Improvement starts from 45% and may appreciably increase depending on the heating time assumed.