Recycled wood has two important functions for sustainable development, as an industrial resource and as a means of longer storage of fixed carbon from carbon dioxide by photosynthesis. Recycled wood-based board, such as medium density fiberboard (MDF), is treated to produce a base material of floor heating system. The concept of functionally graded material (FGM) is introduced for the design of energy saving wood-based board. The heat transfer phenomenon of an FGM base plate used in a floor heating system is modeled and analyzed. The basic equation of the unsteady two-dimensional heat transfer problem and the analytical method for an FGM plate with wood material properties are proposed. The analytical method consists of the Laplace transformation and the perturbation method for arbitrary grading patterns. The results of the numerical calculation suggest that the optimum FGM wood-based board can save more energy than the homogeneous material. (C) 2006 Elsevier Ltd. All rights reserved.