This paper presents a generalized Weber-Feehner's Law.It shows that this law can be used in assessing lighting,acoustical andthermal environment of building.The room articulation funetion,the li-ghting clarity funtion and the thermal comfort function are derived fromthis law.The ealeulated results of these funetions are coincident withthe experimental data obtained by some famous researchers in the world.It can be thought to be a universal law.