<p>Method for vacuum drying a material, particularly timber, where a low temperature is maintained in the material until a predetermined moisture level is achieved, after which the temperature of the material is increased. Material is placed in a drying chamber and produced steam from the drying material is discharged from the drying chamber and compressed by a compression device comprising at least two compression units for raising the heat energy of said steam. This heat energy is transferred from at least part of the compressed steam to the drying chamber through a condenser unit. Steam is added to the compression device, where this additional steam is being heated by external energy before entering the compression unit.</p>
