What is considered the most energy-efficient movable window type?

The casement window is widely recognized as the most energy-efficient type of movable window. This efficiency is primarily due to its design and method of operation. Casement windows are hinged at the side and open outward, which allows for a tighter seal when closed compared to other window types. This tight seal minimizes air leakage, helping to maintain indoor temperatures and reduce energy loss.

Another factor contributing to the energy efficiency of casement windows is their ability to catch breezes and promote natural ventilation more effectively. Being able to open fully, they can enhance cross-ventilation in a home, which can reduce the need for air conditioning on mild days.

In contrast, sliding windows, while easy to operate, often have gaps at the meeting rail, leading to potential air leakage. Awning windows, which open outward from the bottom, can also be efficient but aren’t as tight-sealing as casement windows. Hinged windows, similar to casement windows, can be efficient, but they typically do not achieve the same level of airtightness, especially if they are larger or not maintained properly.

Therefore, the design and operational mechanics of casement windows make them the most effective choice for energy efficiency among movable window types.