Thermal improvements of box-window using shading attachments. Hot-box measurements

Abstract

This research explores shading potential for improving the thermal properties of a box-window. Two different types of shades along with three placements were considered. Ten configurations were tested in a hot-box apparatus and compared to base window performance. Condensation issues that may arise after shading installation were also studied.

Measurements showed that shading installed along with the original box-window has a positive impact on the window thermal performance. The highest U-value reduction by 35% (from 1.9 to 1.0 W/m2K) was achieved by a roller-shade with low-emissivity layer and constrained airflow on shade perimeter, installed inside the window recess. Temperature analysis showed a higher risk of condensation on the indoor window surface due to shade introduction on the indoor side of the window.

Shading placement within the box-window gave improvements of 34% (reduced U-value from 2.0 to 1.3 W/m2K) for reflective roller-shades placed between the window frames. Shades in this position do not increase the risk of condensation on the indoor surface of the window. The probability of condensation inside the box-window may be lowered by draught-proofing indoor frames and maintaining ventilation through the outdoor frame.

Shades proved to be effective at improving the thermal properties of box-windows.