Sunshade plays an increasingly important role in the field of modern building energy conservation. Relevant data shows that window shading saves about 10% to 24% of building energy consumption, but the investment in buildings used for shading is less than 2%, and the benefits are obvious.
With the increasing maturity of building technology, modern building shading has become a development trend, and its functions are also developing in a composite manner. Specifically, it is manifested in three main development directions: the externalization of shading, diversification, and integration with architectural design.
The purpose of shading is mainly to block direct sunlight from entering the room through glass, prevent excessive sunlight from shining and heating the building envelope, prevent glare, and reduce the amount of solar radiation heat entering the room, in order to eliminate or alleviate indoor high temperatures and reduce the power consumption of air conditioning. Therefore, adopting appropriate and reasonable shading measures for different orientations in field design is an effective way to improve indoor environment, reduce air conditioning energy consumption, and improve energy efficiency.
Due to the fact that the building surface is no longer a simple division of internal and external spaces, its functions have become increasingly complex, requiring functions such as shading, lighting, ventilation, and moisture retention. According to the skin division of the shading layer, one is the external shading, which can be divided into horizontal, vertical, comprehensive, etc. Fixed shading is often considered more commonly, in addition to concrete shading.
The advantage of external shading is that the heat generated by solar radiation on the shading layer stays outside the building, which has good heat dissipation. The disadvantage is that it is difficult to protect and maintain. Specifically, the surface of current architectural shading design has had a significant impact on the architectural design. External shading can effectively reduce building heat gain, but the effect is closely related to shading structure, materials, color, and there are also certain defects. Due to direct exposure to the outdoors, not only is it easy to accumulate dust and difficult to clean during use, but also the corrosive effects caused by wind, rain, and other factors should be considered.
In terms of internal shading, there are many available styles, but the effect is not as good as external shading. The internal shading decoration reflects some sunlight, absorbs some sunlight, and penetrates some sunlight, while the external shading only directly reaches the outer surface of the window glass through that part of the sunlight, and some may form a cooling load. Although the internal shading can also reflect some sunlight, the absorbed and penetrated parts become indoor cooling loads, It only delays and attenuates the peak of heat gain. However, as the components are located indoors, they are easy to maintain and clean. In addition, the widely used double skin often places the sun shading layer between two building skin layers. The air layer formed between the double glass layers and the adjustable sun shading layer work together to meet the requirements of building sun shading, natural ventilation, and natural lighting. In a double skin structure, the sunshade is protected by the outer layer of glass to prevent erosion by wind and rain.