Experimental and numerical investigation of the thermal transmittance of PVC window frames with silica aerogel

The poor thermal performance of windows can largely be attributed to their frames, which typically have higher thermal transmittance than the glazing portions. This study investigates an innovative polyvinyl chloride (PVC) window frame modified by inserting silica aerogel granules in the frame cavities. Experimental tests done in a hot box are described and compared with numerical modeling results. The direct object of the comparison was the difference in thermal transmittance of the frame, obtained by insulating frame cavities with aerogel. Both types of tests have confirmed that even with a simple PVC frame, it is possible to achieve at least 30% decrease of its thermal transmittance. The investigations allow discussing the importance of different frame cavities and of the frame orientation. Infrared imaging of the frame within the hot box enables analyzing the significance of the aerogel particle distribution and the edge effects. This paper supports experimentally the results obtained with numerical simulations. The research concludes that filling most of the existing cavities with aerogel granules would reduce the thermal transmittance of the case study frame to 0.80 W/m2K. Finally, this study confirms the feasibility of enhancing window frames with aerogel granules within the frame cavities.