This paper presents a three-dimensional numerical framework based on lattice Boltzman method combined with the energy equation for predicting the thermal properties of saturated fiber networks. Heat transfer in fiber suspensions during hot pressing in paper making process is investigated. The effects of efficient preheating on overall energy savings are discussed. The accuracy of the analytical solution based on the assumption of semi-infinite solid body is also investigated. The results show that the thermal properties change significantly depending on the wood fiber types. The effective thermal conductivities of fiber suspensions for three different fiber types are calculated. The predictions compare well with existing experimental and analytical data.