All works of art, from paintings, frescoes, sculptures, to monuments and buildings, are affected by diurnal and seasonal variations of the local microclimate, which induce interactions with the environmental atmosphere. Heat and vapor exchanges cause fluxes of heat and mass between the surface and the atmosphere, and may favor the aggressivity of environmental pollutants. Condensation-evaporation cycles are recognized as being very important processes which adversely affect the life of the work of art. The need to control the microclimate or to stop condensation processes has been resolved by means of a dew-point signaller especially designed to overcome this problem. This paper discusses the characteristics of this device as well as the environmental philosophy which should be followed when conserving works of art.