Uffizi Galleries in Florence: a comparison between two different air conditioning systems

Two measuring surveys were carried out, one in the winter and the other in the summer, in order to improve the microclimate in the Giotto and Leonardo rooms of the Uffizi Gallery in Florence. Thermohygrometric data (i.e., air and surface temperatures, relative humidity, specific humidity, dew point, atmospheric stability) were taken continuously, both automatically and manually, at regular intervals from before the rooms were opened to the public, to after closure. Continuous optical measurements (based on the Mie theory of aerosol scattering) of the spectral concentration of particles suspended in the air were also taken. The air conditioning in the two rooms examined was controlled by two different systems that functioned at different levels of sophistication. Marked thermohygrometric gradients were generated in the two rooms, and their configuration depended largely on how the air conditioning systems introduced cold air into the rooms and how the air was removed. Both systems led to dishomogeneous and unstable conditions. The circulation forced by the conditioners, the advection between rooms, and the movement of visitors caused turbulence which in turn affected the deposition rate of pollutants onto the works of art.