How curtain wall achieves thermal insulation performance?
Time: Jun 13, 2022

The thermal performance of a monoblock curtain wall is a function of the architectural and perimeter details behind the glass panes, moldings, opaque areas (vaults and pillar coverings).

Curtain wall frame conductance is a function of frame material, geometry and fabrication, as is thermal break.

Aluminum has a very high thermal conductivity. It is common practice to thermally break low conductivity materials, conventional PVC, neoprene, polyurethane and more recently nylon reinforced polyester, to improve thermal properties. Due to the temperature difference, the outer aluminum moves differently than the inner aluminum. Some "poured and clean" polyurethane hot cracks will shrink and form stresses at the location of the hot cracks. An alternate mechanical connection is recommended for the two halves of the frame (eg jumping off the bridge or "t-in-a box"). True thermal break has a minimum thickness of ¼" and can reach 1" or more, polyester reinforced nylon varieties. Some façade systems integrate partitions of less than ¼, which allows an "improvement of thermal performance". Deeper thermal break can improve the thermal performance and condensation resistance of the system.

Some curtain wall systems use "pressure bars" (also known as "pressure plates") attached to the outside of the vertical frame to retain the glass. These systems often include spacers that are placed between the pressure bar and the vertical frame to act as a thermal break and aid in sound insulation. These systems require special care in terms of design and construction to ensure the continuity of the spacers in the horizontal and vertical transition. A liner is also used to dampen the glass on its inner and outer surfaces. The problem with gaskets is that they tend to stretch during installation and shrink to their original length in a short amount of time; They also retract with age and exposure to UV rays. After contraction, spacers in the corners often have empty spaces. The system is well designed that the water entering the system, at the corner of the washer, will flow through the outlet hole of the pressure cap. To reduce gasket shrinkage at corners, it is recommended to use vulcanized corners and angled cutting and splicing.

The thermal performance of the opaque area of ​​the facade is a function of the thermal insulation and the air/vapour barrier. Due to the lack of indoor air near opaque facade areas, temperature and humidity fluctuate significantly in these areas, which requires careful design of insulating materials and air/vapor barriers to minimize condensation. Some curtain wall systems include condensate drain units, such as condensate chutes, designed to collect and drain condensate from the exterior wall area; Such condensate chutes and flow chutes are a violation of the curtain wall air barrier unless they are located on the outside of the rear tray. See the rear tray discussion below.

At the perimeter of the curtain wall, maintaining air barrier continuity reduces airflow around the curtain wall. Peripheral flash integration helps ensure curtain wall waterproofing and connection to adjacent wall elements. Proper placement of insulation around the curtain wall reduces energy losses and potential condensation problems. Insulation of the vertical frame in the vault area can cause excessive condensation in cold climates unless it is also ensured that moist air from inside never comes into contact with the vertical frame. The rainbow area is usually not heated, so the interior environment does not heat the walls and counteracts the migration of cold temperatures to the deeper walls. In the visual area, the internal heat helps to alleviate the cold and prevents condensation. Therefore, do not insulate between the inner part of the vertical and the adjacent wall building.

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