The thesis considers a stabilization of temperature of a wood fiber during production of medium close fibre boards MDF in a wood-processing industry. The original purpose to solve energetic optimalization of a kiln dryer has become a serious problem. It turned out that production suffers with a big heat loss which results in big heat loss gained during a kiln drying. Primary aim of this thesis is an examination of a cooling effect of environment on chosen parts of a production line and suggestion of acceptable proceeding to minimize heat loss and to rise temperature of the wood fiber to required temperature. Solution is aimed on the section of a production line between drying equipment and press. First part of the thesis introduces technology of production of fibre boards, introduction to heat transfer problems and also basics of computer modeling of heat flow and transfer using CFD simulation. The next part includes an evaluation of the heat loss of chosen parts of the production line in a current working condition and its comparison with computer simulations. Verification of accuracy of the results while using both approaches to solution is a first step to the improvement of the current situation. It is possible to use the verified calculation model for the following solution of effects on convective and radiation heating of a wood fiber layer. An important factor in the last period of a calculation is a real temperature of the fiber board-mat at the entrance to a press. The higher entering temperature in a set temperature range is reached, the lower time needed for pressing will be and simultaneously the whole industrial process will be cut short. The solution of a problem leads to an achievement of an energy saving and should become a solid basis from which it would be possible to evaluate an improvement of production of MDF boards. The conclusion of the thesis includes an analysis of findings which refers to a heating of wood fiber and it’s effectiveness for a practical use.