Nocturnal temperature measurements of various infrared selective radia
tors performing radiative cooling have been carried out. Measured temp
erature differences between the radiators and ambient temperature were
about 10-degrees-C. Radiating surfaces have been prepared by applying
different kinds of paints on aluminium substrates. It was shown that
the addition of a BaSO4 extender in the paint dispersion increased the
cooling performance of the paint radiators. Comparisons between predi
cted cooling performances by calculations and measured ones are discus
sed in detail.