Window Coverings Energy Efficiency

We were aware that there were a lot of extravagant claims circulating, regarding the impact window coverings can have on energy bills. We commonly saw “Reduce energy bills by 80%, 70% or 40%“ and wanted to test the possible accuracy of these claims and use the results to develop and improve our understanding of how window coverings impacted on heat gain or loss and light block out. With this improved understanding we would be able to advise clients more effectively and improve our own product range.

We sought academic help in designing our experiment, anaylsing the data and writing the report VIEW WINDOW COVERINGS STUDY REPORT

We constructed a laboratory and equipped with 2 testing cells, one with an ‘ultimate window covering’ (UWC) – a polystyrene panel 60mm thick, used as a control and to set a benchmark. The other cell was used to measure and monitor the light and temperature of a variety of window coverings and in what turned out to be crucial, different colours.


At its most simple, the testing was done by creating two identical, thermally-stabilised ‘rooms’. The entire test environment was stabilised with 24-hour air-conditioning to 22C. Two simple heat sources were applied to the rooms with precisely the same amount of heat and a window covering was placed in one of the test rooms to test against the control room.

Testing was run for close to a two year period.

The UWC produced a reduction in heat gain by 39.7% which we knew from previous University of Newcastle research was close to the maximum possible of 40%. Generally heat gain or loss from an average house would be 40% through the windows.

The best performing internal window coverings to prevent heat gain were white western red cedar plantation shutters

And the best performing for light block out was black Eco frame Aluminium planation shutters

We found that colour had an enormous impact, white was much better at reflecting radiant heat ie heat generated from light and black was much better at absorbing light rays.


Product Development.

From this study we developed a z shaped frame for our internal Aluminium Plantation Shutters and included a rubber seal. This created a sealed unit when the blades were closed and prevented the movement of the heated air into the room.