The use of LEDs (Light Eraser Diodes) for facade lighting was relatively rare a few years ago, still considered a novelty, but it has become quite common now. This is due to economic development and the inherent advantages of LEDs. This article introduces the use of LEDs in facade lighting for reference by industry professionals. 1. Project Overview The Huaye Rose Oriental project is located at No. 25, Yanjingli Middle Street, Chaoyang District. It comprises eight buildings with a total construction area of ​​approximately 250,000 m2. Buildings 1, 2, and 3 are high-rise residential buildings, 18 stories high, with a height of over 50 meters. Building 8 is primarily a public building (Huaye International Center), with a podium below the third floor, approximately 127 meters long east-west and 70 meters wide north-south. Above the fifth floor are two partially high-rise buildings, both 17 stories high, with a building height of 66 meters. The entire above-ground portion of the building features a concealed-frame glass curtain wall. The eastern end of Building 8 and some of the high-rise buildings are located near the East Fourth Ring Road. 2. Facade Lighting Overview 1) After several rounds of bidding and scheme comparison, only facade lighting for Building 8 was finalized. Specifically, 200mm x 200mm LED white dot lights will be installed at the intersections of the stained glass windows on the second floor and above on the east, south, and north sides of Building 8. Each LED light will have a capacity of 7W or more. The installation location of the facade lighting lights and the relationship between the stained glass and the floor slab are shown in Figure 1; the position of the facade lighting lights within the stained glass is shown in Figure 2; and the shape of the facade lighting lights is shown in Figure 3. 2) Advertising lighting will be installed on the roof of the east tower on the east, south, and north sides of Building 8, facing the East Fourth Ring Road. The advertising lighting will use a floodlight scheme. 3) Facade lighting and advertising lighting will be controlled separately. Facade lighting will not require individual or partial control; a full-on/full-off control method will be adopted. The control of both facade lighting and advertising lighting will be centralized in the building control room on the first floor of Building 8. 3. LED Lighting Solution Demonstration The initial plan for this project was to install facade lighting for both residential and public buildings. Our company's tender proposal did not specify the light source, but all the lighting companies participating in the bidding unanimously adopted LED lighting for Building 8. From a cost-saving perspective, our company was initially not optimistic about the LED solution. A Shenzhen company proposed installing fluorescent lights on the rooftops of each floor near the glass curtain wall, which was favored by some (see Figure 4). This solution was good in terms of both the aesthetic effect of facade lighting and cost savings, but it had a fatal flaw: light pollution for residents whose homes were equipped with fluorescent lights. As long as there were residents in Building 8, it would cause light pollution to them. Residents might complain or even deliberately damage the fluorescent lights installed in their homes. When repairing or replacing fluorescent lamp tubes, maintenance personnel must bring ladders to the residents' homes to complete the work. Erecting the ladders may require moving residents' furniture, potentially leading to refusals or resentment, especially when residents are frequently away on business or abroad. The inability to repair damaged lamps can prevent the overall facade lighting from functioning effectively for extended periods. If Building 8 were entirely for office and commercial use, light pollution would not be a concern. Therefore, the prerequisite for using fluorescent lighting was confirming that Building 8 would be entirely for office and commercial use. However, after determining that Building 8's function would be partly or mostly hotel-style apartments, the fluorescent lighting plan was abandoned, and a plan to install LEDs or other light sources behind stained glass was adopted. After repeated research and comparison, the LED light source plan was selected. See Figure 5 for the LED plan's effect diagram, Figure 6 for the facade lighting installation diagram, and Figure 7 for the system diagram. [ALIGN=CENTER] [/ALIGN] 4. Characteristics of LED Lights : LEDs are semiconductor light-emitting devices that transmit very little current, converting almost all of it into visible light. 1) High luminous efficacy: LEDs have a luminous efficacy of 50-200 lm/W, a narrow spectrum, and good monochromaticity. Almost all emitted light can be utilized, and colored light is emitted directly without filtering. 2) High energy efficiency: LEDs feature low voltage, low current, and high brightness. The light energy emitted by a 10-12 W LED light source is equivalent to that of a 35-150 W incandescent bulb. For the same lighting effect, LEDs save 80%-90% more energy than traditional light sources. 3) Multiple light colors: White or colored light can be selected, including red, yellow, blue, green, yellow-green, and orange-red. Multi-color combinations and cyclic color-changing lamps can be manufactured as needed. 4) High safety: LED light sources use low-voltage 12VDC driving, providing stable light emission, no pollution, no 50 Hz flicker, no UVB band, a chromaticity/color body R value close to 100, and a color temperature of 5000 K, closest to the solar color temperature of 5500 K. 5) Diverse Design Shapes: LED light sources are composed of many individual LEDs, allowing for a wider range of shapes compared to other light sources. This makes it easier to design the shape and size of the light source to suit specific user needs. The LED lamp shape adopted by the lighting company bidding for our project is shown in Figure 3. 6) Long Lifespan: LEDs utilize solid-state semiconductor chips to convert electrical energy into light energy, encapsulated in epoxy resin, enabling them to withstand high-intensity mechanical shocks. A single LED has a lifespan of 100,000 hours; even working 12 hours a day, the lifespan is over 20 years, resulting in low maintenance costs. 7) Fast Response: LEDs have a very short response time, ensuring smooth switching between multiple light sources or different areas of a single light source. When powered by a dedicated power supply, the time to reach maximum illuminance is less than 10ms. [ALIGN=CENTER] Figure 7 System Diagram[/ALIGN] Note: 1- The power distribution control box is located in the electrical conduit shaft on the 1st floor. The floor gate distribution box is installed in the electrical conduit shaft on each floor. The main power line of the floor is installed in the high-voltage cable tray inside the conduit. 2-LED light distribution circuits are all protected by leakage current switches. 3-YJV-3mm×10mm is used from the first-floor distribution control box to the floor distribution box; BV-2mm×4mm is used from the floor distribution box to the LED lights. 8) Reasonable lamp structure: LED lamps will completely change the structure of lamps. According to different professional usage requirements, the structure of LED lamps, while improving the initial brightness, further enhances the brightness through rare earth elements. Through the improvement of optical lenses, its luminous brightness is further improved. 9) Low operating cost: Other light sources consume only 2 to 10 times more power than LED light sources, and currently, some need to be replaced almost every month, wasting a lot of valuable time for maintenance engineers. Moreover, the more light sources are used, the greater the cost in terms of component replacement and labor. The initial investment savings are quickly offset by daily maintenance and repair costs. Therefore, choosing long-life LED light sources is very economical in the long run. 5. Performance Comparison Compared to traditional lighting sources such as energy-saving lamps, metal halide lamps, tungsten filament lamps, magnesium-neon lamps, fluorescent lamps, neon lamps, and cold cathode lamps, what are the advantages of LED light sources? The attached table compares the performance of LED light sources and common light sources under normal circumstances. 6. Comparison of LED and Neon Lamps 1) Light Source Comparison Neon lamps are low-pressure cold cathode glow discharge light sources. The lamp tube is made by coating a glass shell with phosphor, sealing it at high temperature, and then sintering it with inert gas and mercury after vacuum filling. Unlike hot cathode lamps, it does not have a tungsten filament, has better shock resistance, higher luminous efficiency, and a longer lifespan (theoretically up to 30,000 hours). The light source can be frequently turned on and off without affecting the lamp tube's lifespan, and it offers rich and vibrant colors. This light source is currently still in the semi-automated, semi-manual, or purely manual production stage. LED light sources are solid-state light sources that do not require gas filling or a glass shell. They have good impact resistance, shock resistance, and are not easily broken, making them easy to transport. The light source unit is small, allowing for a wide range of applications. They also have higher luminous efficiency, are more energy-saving, and have a longer lifespan, theoretically reaching 100,000 hours. The light source can be frequently switched on and off without affecting its lifespan. They offer rich and vibrant colors and are mercury-free, making them an environmentally friendly light source. 2) Power Supply Comparison: LED light sources use low-voltage DC power, making insulation easier. They typically use low-voltage 24V or 12V switching power supplies, offering high flexibility, wide application range, and convenient and safe installation. 3) Control Technology Comparison: Because LED light sources use low-voltage DC power, they have the characteristics of low load and weak interference; neon lights use high-frequency, high-voltage power, resulting in high load and strong interference. 4) Market Status Comparison: In recent years, due to power shortages and the government's high emphasis on energy-saving light sources, the annual growth rate of LED light source usage in various fields has reached 30% to 40%. Markets traditionally dominated by neon lights, such as landscape engineering, advertising lighting, and decorative lighting, have been squeezed out to varying degrees by LED light sources. In interior lighting projects, LED light sources, due to their small unit size and ease of control, are trending towards replacing neon lights and may become the dominant light source for interior decoration. A few thoughts: In the early days of reform and opening up, floodlights were used to renovate many facades that previously used incandescent bulbs for outline lighting. At that time, almost all facade lighting adopted floodlights; in fact, "floodlighting" became synonymous with facade lighting. Floodlights are more energy-efficient, have a longer lifespan, and are easier to control than incandescent outline lights. Replacing the previously used incandescent outline lights with floodlights was the right thing to do at the time. However, floodlights are installed on low ground or shelves to project light onto buildings, causing light pollution to pedestrians on the ground and people inside the illuminated buildings—this is their fatal weakness. Therefore, such designs have decreased in recent years. In recent years, Lishan Lighting has emerged in Beijing, installing fluorescent lights within the glass curtain walls of each floor of taller buildings. This type of facade lighting is a good solution in terms of aesthetics and cost savings. Compared to floodlights, it reduces or eliminates light pollution to the ground and pedestrians, but it does cause light pollution to residents inside the building. This can lead to conflicts between residents and property management, potentially resulting in adverse consequences. When using LED lights for facade lighting, because the LED lights are installed on the glass curtain wall at the floor level and shine outwards (see Figure 1), they do not cause light pollution to residents. Furthermore, LED lights have a long lifespan and require minimal maintenance; even occasional repairs to residents' homes do not require ladders or other tools, minimizing disruption. This should be a priority for facade lighting. A process of understanding is needed to address this. Facade lighting is an important project for beautifying cities, buildings, and enhancing the image of buildings and developers. On this point, the goals of the government, developers, and residents are aligned. However, achieving this goal requires considering the interests of all parties, taking into account the building's appearance, function, structure, and environment. Simultaneously, human-centered design should be emphasized, selecting the best solution from multiple options. LEDs do not rely on filament heating to emit light, resulting in extremely high energy conversion efficiency. Theoretically, they can achieve energy consumption only 1/10 that of incandescent lamps. Compared to fluorescent lamps, LEDs can achieve 50% energy savings. LEDs use solid-state packaging, resulting in a robust structure and a lifespan of 100,000 hours, which is 10 times that of fluorescent lamps and 100 times that of incandescent lamps. In terms of environmental protection, a special survey conducted by the Office of the Project Promotion Office for Replacing Fluorescent Lighting with LEDs revealed that my country's annual green lighting electricity consumption exceeds 300 billion kWh. Replacing all or part of incandescent lamps with LEDs, saving one-third of lighting electricity, translates to a saving of 100 billion kWh, equivalent to the annual power generation of the Three Gorges Dam project, with a total investment exceeding 200 billion yuan. This is undoubtedly of great significance to my country, a country facing severe energy shortages. Countries around the world attach great importance to the research and development and production of LEDs: the United States' "Next Generation Lighting Initiative" (NGLI), formulated in 2000, was included in the Energy Act, with the plan to replace 55% of incandescent and fluorescent lamps with LEDs by 2010, forming a semiconductor lighting industry market with an annual output value of more than $50 billion; the European Union's "Rainbow Project" was launched in July 2000, promoting the use of LEDs through special subsidies from the European Union. In 2003, my country established the "National Semiconductor Lighting Engineering Coordination Leading Group," a cross-departmental, cross-regional, and cross-industry organization led by the Ministry of Science and Technology. During the "10th Five-Year Plan," a major project on key technologies for the industrialization of semiconductor lighting was urgently launched. During this period, in conjunction with the formulation of the National Medium- and Long-Term Science and Technology Development Plan and the "11th Five-Year Plan," an overall strategy and implementation plan for the development of China's semiconductor lighting industry were researched and proposed. The "construction of a resource-saving society" will drive the rise of numerous "resource-saving industry" concept stocks. As the market rapidly bottoms out, a rebound is likely at any time. The new energy sector, after its surge, has entered a period of adjustment, and the LED energy-saving lighting sector, with its greater development potential, is expected to take over the leading role. Currently, LEDs are mainly used in landscaping and public utilities, and they have a clear advantage among various energy-saving light sources. With the Beijing Olympics and the Shanghai World Expo approaching, LED applications will not only illuminate landmark buildings and countless windows, but will also illuminate a multi-billion dollar industry.