Definition of Four-character Test for Building Facade

(1) Inspection Content: Building Facade Air Tightness, Water Tightness, Wind Resistance, and Plane Deformation Performance.

(2) Inspection Nature: Inspections conducted to determine if the curtain wall in the project meets the design requirements. Performance testing of the curtain wall should be carried out for every curtain wall project.

(3) Other Matters: Currently, the four-character tests for engineering curtain walls in China are only conducted on the samples of the curtain walls, with the test results being responsible for the samples only (Figures 1, 2).

(4) Timeline and Purpose of Four-character Testing: 1) Timeline: Generally, it should be conducted after the completion of engineering design, prior to the mass production, processing, and installation of facade components. 2) Purpose: To verify the correctness, rationality, processability, and cost-effectiveness of the facade design, to determine if it meets the design performance criteria; also, to provide a basis for improving the design, refining the processing, assembly, and installation methods; and to enable construction personnel to familiarize and master the operational procedures and methods through the processing, assembly, and installation of facade samples.

Glass Façade Four Properties Test: The four properties testing of glass facades includes wind resistance performance testing, air tightness testing, water tightness testing, and in-plane deformation performance test.

Glass Facade Wind Pressure Resistance Test: Refers to the ability of the facade to maintain normal operational functions and not sustain any damage under the action of wind loads perpendicular to it.

Air tightness performance test of glass curtain wall: refers to the ability to prevent air from passing through the curtain wall when the opening part is in a closed state under wind pressure.

Water-tightness Test for Glass Façade: Water-tightness is related to the functionality and lifespan of the facade, influenced by the building's importance, use, and the local climatic conditions. The grading is based on the average wind pressure over 10 minutes.

According to the relevant contents of the "Code for Acceptance of Construction Quality of Energy-saving Projects for Building Envelope" GB50411-2007, when materials and components for energy-saving curtain wall projects are delivered, their following performance should be re-inspected, and the re-inspection should be conducted through witnessed sampling and testing.

(1) Insulation Materials: Thermal Conductivity, Density.

(2) Curtain Wall Glass: Visible Light Transmittance, Thermal Conductivity, Solar Heat Gain Coefficient, and Dew Point of Insulated Glass.

(3) Insulating Profiles: Tensile Strength, Shear Strength.

(4) The air tightness performance of the curtain wall should meet the grade requirements specified in the design. When the area of the curtain wall exceeds 3000m² or 50% of the building's exterior wall area, materials and accessories should be sampled on-site, and test specimens should be installed and manufactured in a testing laboratory for air tightness performance testing (the test specimens should include typical units, typical joints, and typical operable sections of the curtain wall). The design of the specimens should be in accordance with the construction drawings for the curtain wall project. The design should be approved and confirmed by the project manager of the architectural design unit and the supervisor engineer, and the test results should comply with the grade requirements specified in the design.