In this paper, heat loss is precisely computed by a proposed code considering different climates. Estimating the costs of different central heating system, unit heaters were selected as the most feasible system. Finally, considering heating capacity and unit heater’s dimensions a CFD model was developed to find optimized configuration of unit heaters in a typical greenhouse. Using this model, required thermal load for a greenhouse based on daily temperature of Arak city in 2017 was computed with a smart control system. It was found that savings in energy consumption was about 5447 m3 of natural gas in each year.