Thermal Performance Improvement of Window Drape Configurations

Abstract

Heat transfer through draped windows was studied to identify and test the insulative potential of drapery materials and configurations on a window in a test wall apparatus. Free flow of room air through the window-drape cavity was found to produce dramatic losses in the insulating properties of drapes. Variations of open-bag and wind-screen draping configurations made of conventional drape materials reduced window thermal transmittance values by 50%, a reduction equal to that expected from converting heat transfer from a free convective mode to a conductive mode at the window glass/room air interface. Materials with ideal properties for control of radiative and conductive heat flow were also used as draping elements to quantify the performance levels of the drapes configured to impede natural convection. Simulated drapery materials having radiation barriers configured to minimize air flow were as effective as double pane windows.

Guarded Window Test Apparatus for Determining the Insulation Value of Interior Window Coverings

“…Tomany's results are consistent with the results obtained from a guarded window test apparatus, in use in the JCPenney Merchandise Testing Center, for the winter percent reduction in heat loss as the result of installing roller shades [6]. In another study, Hassenboehler and Donoghue [4] discuss the importance of air flow around a window treatment and past the surface of their test window.…”

Passive solar heating through glazing: The limits and potential for climate change mitigation in the European building stock

“…This variation in the energy properties of an IGU can be achieved if we consider the entire window as a dynamic element. Blinds and shutters, thermal curtains or storm windows all provide varying insulation with considerable impact on building efficiency [26,27]. Thus, further research is needed to assess the passive solar heating potential of different types of window designs.…”

A Test Method to Establish R–Values of Materials Used in Energy Conserving Window Coverings

“…Some require actual installed window treatments, mockup windows, controlled conditions of shading and wind, cold outside conditions or perhaps refrigeration systems, etc. (Anderson, 1982;Fullarton & Mahan, 1983;Hassenboehler & Donoghue, 1981).…”

“…Consumers and specifiers therefore have no valid bases on which to make comparisons of the insulative effectiveness of various window products (Rymer, 1982). Methods of installation vary from site to site, as do the number of glazings, wind factors, and the human management of the treatments (Hassenboehler & Donoghue, 1981). So it is theorized that using one constant, single factor, R-value, for comparison of effectiveness is a logical approach.…”