Providing a feasible energy retrofitting technique based on polyurethane foam injection to improve windows performance in the building stock

Abstract

Energy renovation of existing buildings represents an outstanding potential field for providing efficient, viable and easy-to-produce retrofitting techniques that allow addressing energy targets under a global warming scenario. Aiming to fulfil a current research gap on promoting feasible passive techniques to improve thermal performance in the building stock, this research contributes with the design, procedure and in situ application of a novel energy retrofitting solution based on the injection of polyurethane foam insulation in carpentry profiles of existing aluminium windows, which implies relevant insights towards energy efficiency and ensures more comfortable indoor environments through a quick, non-destructive and affordable solution. This innovative plan has been experimentally tested in social housing, with a monitoring campaign during summer conditions, allowing to obtain thermal results before and after the insulation injection treatment. The key outcomes highlight a favourable indoor thermal balance after the foam injection, increasing the thermal jump up to 25 % or more than 4 °C net, as the daily maximum temperature difference recorded between outdoor and indoor simultaneously. Conclusions incorporate key implications to technicians, manufacturers and construction firms, on introducing new possibilities for improving energy efficiency in existing aluminium windows with low investment, linked towards an efficient management of the built environment.