A mathematical model consisting of algebraic equations was developed for greenhouse heating integrated with a heater exchanger. The works on the principal of utilizing the waste heat from the biogas fuel engine. The equations were used by MATLAB program for four components of the greenhouse, cover, inside air, plant and soil. It was assumed that the greenhouse air is well mixed. Thermal properties of construction materials are constant and solar radiations pass through cover without absorption. The analysis is based on the energy balance equations for different components of the greenhouse. The model is developed to calculate the hourly temperatures of greenhouse components under climatic parameters. Experimental validation of the developed model is carried out in Ostobary, Shibin El-Kom, Minofiya latitude angle is 30^o 54^' north during November 2009 to March 2010. The results of computer model (predicted data) were compared with the experimental results. The minimum correlation coefficients between values were 0.970, 0.975, 0.970, 0.977 and 0.818 for air, soil, cover, plant and relative humidity respectively. The minimum temperatures were 13, 12.77, 13.57 and 15.8 ^oC for air, cover, plant and soil. Good agreement between the predicted and measured values was obtained during the entire modelling period. This means that the model can be used to predict a thermal performance of the greenhouse elements in a wide range of solar radiation and temperatures. Using waste heat as an input for greenhouse operations is a new mechanism for reducing operating costs.