For installation in buildings or in solar energy applications, one will often have to mount the CNR 1 parallel to the surface that is being studied. This may be in a tilted, or a vertical position. The sensitivity of the radiometers will be affected, but only in a minor way. This is specified as the so-called tilt effect. From the specifications in chapter 2 one can see that the tilt effect (this is change in sensitivity) remains within 3 %.