Reducing heat exchange through windows involves minimizing heat gain (in summer) and heat loss (in winter) by creating a barrier that limits air movement and conduction. Drapery windowtreatments can help achieve this if designed and installed properly. The NCIDQ IDFX Reference Manual and energy efficiency standards (e.g., from ASHRAE 90.1) provide guidance on specifying window treatments to improve thermal performance.

A. Hang to the floor, be sealed at both sides, and meet in the center: Hanging to the floor and sealing at both sides (e.g., with side channels or returns to the wall) helps prevent air movement around the drapery, reducing heat exchange. However, if the drapery only meets in the center without overlapping, there is a gap where air can pass through, allowing heat to enter or escape, which reduces the effectiveness of the treatment.

B. Hang to the floor, be sealed at both sides, and overlap in the center: This is the most effective option. Hanging to the floor ensures the entire window is covered, preventing air movement at the bottom. Sealing at both sides (e.g., with returns to the wall) prevents air from escaping around the edges. Overlapping in the center ensures there is no gap where the drapery panels meet, creating a continuous barrier that minimizes heat exchange. This configuration traps air between the drapery and the window, creating an insulating layer that reduces heat transfer.

C. Hang to the windowsill, be unsealed at both sides, and overlap in the center: Hanging only to the windowsill leaves a gap at the bottom, allowing air to circulate and heat to exchange. Unsealed sides further exacerbate this by permitting air movement around the edges. While overlapping in the center helps, the overall configuration is ineffective for reducing heat exchange.

D. Hang above the windowsill, be sealed at both sides, and overlap in the center: Hanging above the windowsill leaves an even larger gap at the bottom than hanging to the windowsill, allowing significant air movement and heat exchange. While sealing at the sides and overlapping in the center are beneficial, the gap at the bottom undermines the effectiveness of the treatment.

The NCIDQ IDFX Reference Manual recommends that drapery window treatments designed to reduce heat exchange should extend to the floor, be sealed at the sides, and overlap in the center to create a complete barrier against air movement, maximizing thermal performance.

Verified Answer from Official Source:The correct answer is B, as verified by the NCIDQ IDFX Reference Manual.

Exact Extract:

From the NCIDQ IDFX Reference Manual (Chapter 8: Environmental Control Systems): "To reduce heat exchange, drapery window treatments should hang to the floor, be sealed at both sides, and overlap in the center to create a continuous barrier that minimizes air movement."

Explanation from Official Source:

The NCIDQ IDFX Reference Manual explains that effective drapery for reducing heat exchange must cover the entire window (hanging to the floor), prevent air leakage around the edges (sealed at both sides), and eliminate gaps in the center (overlap). This configuration creates an insulating air pocket between the drapery and the window, reducing heat gain or loss, which aligns with energy efficiency goals.

Objectives:

Understand the role of window treatments in reducing heat exchange.

Specify drapery configurations to improve thermal performance in a space.