Basic Knowledge of Door and Window Design

Doors and windows are indispensable components of a building. How can we design them to be both aesthetically pleasing and fully compliant with architectural requirements and functional needs? Below, we outline some fundamental principles and perspectives.

High-quality doors and windows must meet a variety of functions, including natural lighting, architectural aesthetics, ventilation, rain protection, thermal insulation, and soundproofing, thereby providing occupants with a comfortable and tranquil indoor environment.

I. Architectural Design of Doors and Windows

1. From the perspective of architectural aesthetics, the grid pattern of window and door facades should conform to aesthetic principles. When designing the grid, the following factors should be taken into account:

(1) The vertical grid of doors and windows should strike a balance between regularity and variation, seeking order within diversity. The spacing and density of the grid lines should be carefully calibrated: uniform, evenly spaced divisions convey rigor, solemnity, and formality, while irregular, free‑form divisions evoke rhythm, liveliness, and dynamism.

(2) Coordination of the grid proportions. For each individual glass panel, the length-to-width ratio should ideally approximate the golden ratio; it is inadvisable to design panels as perfect squares or as elongated rectangles with a length-to-width ratio exceeding 1:2. The muntin height is typically set at 1/4 to 1/5 of the frame height, and should neither be excessively large nor overly small.

(3) At a minimum, the horizontal division lines of doors and windows within the same room and on the same wall should be aligned as closely as possible on the same horizontal plane, and the vertical lines should be kept as parallel as possible.

(4) When designing the elevation of doors and windows, it is essential to consider the building’s overall aesthetic requirements, such as the interplay between solid and void, light-and-shadow effects, and symmetry.

2. Selection and coordination of door and window colors (including the colors of glass and profiles) 　

The selection and coordination of door and window colors is a crucial factor in shaping the final aesthetic of a building. Door and window hues should be harmonized with the building’s architectural character, and their color scheme should be jointly determined through consultation among the architect, the owner, and other stakeholders.

3. Customized Design of Doors and Windows

Unique window and door facade designs can be created to suit customers’ diverse tastes and aesthetic preferences.

4. The transparency of doors and windows

Within the line-of-sight height range of the primary viewing plane of the door and window facade. (Approximately 1.5 m to 1.8 m) It is best to avoid installing horizontal and vertical mullions to prevent obstructing the view. Some doors and windows require high‑transmittance glass or a wide, unobstructed field of vision to facilitate viewing the outdoor scenery.

5. Daylighting and Ventilation of Doors and Windows 　　

The ventilation area of doors and windows, as well as the number of operable sashes, shall meet the building’s ventilation requirements; meanwhile, the daylighting area of doors and windows shall also comply with the “Architectural Daylighting Design Standard.” In accordance with the provisions of GB/T 50033-2001 and the requirements of the architectural design drawings, Article 4.2.4 of the “Energy Efficiency Design Standard for Public Buildings” (GB 50189-2005) stipulates that the window-to-wall area ratio for each orientation of exterior windows shall not exceed 0.70. When the window-to-wall area ratio is less than 0.40, the visible light transmittance of the glazing shall not be less than 0.4.

II. Safety Design of Doors and Windows

1. Wall thickness requirements for aluminum profiles used in doors and windows 　

The wall thickness of aluminum profiles for windows complies with the current national standard’s high-precision grade, and the minimum wall thickness of load-bearing members is… ≥1.4 mm. Load-bearing members of doors and windows (such as the sash rebate, center post, lower sliding sash with transom, upper sliding sash with transom, and double‑sided mullion) must undergo rigorous compressive strength calculations. When profiles serve as load-bearing elements, their wall thickness shall be determined by calculation based on the service conditions. Load-bearing components of aluminum alloy doors and windows shall be verified through testing or calculation.

2. Safety Design for Door and Window Glass

(1) Glass selection: The glass thickness shall be determined by calculation and shall not be less than 5 mm. Safety glass (tempered glass or laminated glass) must be used for doors and windows in the following areas of the building:

(a) Outward-opening windows on buildings of seven stories or more;

(b) Window glass with an area greater than 1.5 m²;

(c) Floor-to-ceiling windows with a glass bottom edge less than 500 mm from the finished floor surface;

(d) Inclined windows with an angle of inclination less than 75° relative to the horizontal and located more than 3 m above the indoor floor level.

(e) Framed glass doors with a glass area greater than 0.5 m²;

(f) Frameless glass doors shall be constructed with tempered glass having a thickness of not less than 10 mm.

(2) The overlap dimension between the glass and the groove, as well as other mating dimensions, shall comply with the requirements specified in Tables 5 and 6 of “Aluminum Alloy Windows” (GB/T 8479).

(3) The glass shall be in flexible contact with the aluminum alloy frame groove via rubber gaskets.

(4) Glass shall undergo mechanical edge grinding, with the abrasive wheel having a grit size of 180 mesh or higher.

3. Selection and Design of Hardware Accessories

(1) When selecting hardware accessories, prioritize products with proven quality. The quality grade of the hardware should match that of the doors and windows, its structure and shape should be compatible with the profile, and its color should be harmonious and aesthetically pleasing. Additionally, it should offer proper functionality, smooth operation, and easy installation.

(2) Hardware fittings shall be fully installed, conform to standards, be securely fastened, and positioned accurately. Following installation, doors and windows shall exhibit an aesthetically pleasing appearance, open smoothly and conveniently, and must not exhibit any deformation, obstruction, or impact.

(3) Exposed fasteners for hardware accessories shall, as a priority, be made of stainless steel.

(4) For casement windows and doors, as well as large sliding windows and doors, multiple locking points should be used when closed; otherwise, the airtightness will be significantly compromised under negative pressure differentials. To ensure ease of operation, it is preferable to use multi-point locking handles or actuators.

In short, designing doors and windows requires a holistic approach that balances aesthetics, safety, and functionality. The exterior should be visually appealing, while the products themselves must be meticulously engineered across multiple dimensions, including profile thickness, glass thickness and area, and hardware components.