Statistical behaviour of wind energy at a single site is derived by considering simultaneous variations in the pressure, temperature and wind speed measurements. The main purpose is to approximate the probability distribution function of the wind energy and consequently, provide a basis for assessing the risk and reliability associated with the energy assessments. The statistical parameters, namely, the mean value and variance of wind energy, are found in terms of simple statistical parameters of temperature, pressure and wind speed. The elegance of these parameters is that they are distribution free. These parameters provide a means for defining the wind energy distribution function by employing the Chebyschev's inequality. Necessary simple charts are given for the risk and reliability assessments. Two procedures are presented for such assessments in the wind energy calculations and the application of these procedures are provided for a wind energy potential area within the northeastern part of Turkey. Copyright (C) 1996 Elsevier Science Ltd.