The electrical energy-saving design of existing buildings can not be sacrificed at the expense of building functions and damage to the needs of use, nor can it blindly increase investment and save energy for â€œenergy savingâ€. Therefore, the author believes that the principles of electrical energy-saving design should include the selection of transformers, power supply and distribution systems and circuit design, improve system power factor, lighting energy saving, motor energy saving, and selection of power-saving low-voltage electrical appliances. This article will only further explain the lighting energy savings of large-area offices.
2 Lighting Energy Overview
Due to the large amount of architectural lighting, the potential for energy saving in lighting is great. The lighting energy-saving design needs to select the illuminance standard value according to different places, different functional requirements and different standards; select high-efficiency energy-saving light source, lamps and electrical accessories; reasonably select the lighting mode and lighting control mode. Select the lighting power density value in accordance with the national GB50034-2004 "Architectural Lighting Design Standards".
(1) Scientific selection of electric light source
The scientific selection of electric light sources is the primary issue in lighting energy conservation. At present, the luminous efficiency, life and color rendering performance of domestically produced electric light sources are constantly improving, and energy-saving electric light sources are constantly emerging. In terms of the light effect of the light source, the gas discharge light source is higher than the heat radiation electric light source. In the past design, the incandescent lamp that we used to use is a heat radiation source, and the light effect is low, the life is short, and the power consumption is high. Among all kinds of lamps, T8 thin tube fluorescent lamps and compact fluorescent lamps that we are promoting now are 5% higher than ordinary fluorescent lamps, and thin tube fluorescent lamps are 10% more energy efficient than ordinary fluorescent lamps. Because of its high luminous efficiency, fast start-up, and good color rendering, it is mainly used for indoor lighting, except for incandescent lamps in places such as electromagnetic interference and frequent switching. Of course, the use of metal halide lamps in tall spaces is a good choice. Mercury and sodium lamps are used for outdoor lighting, or they can be combined for mixed lighting. This design has high luminous efficiency, low power consumption, realistic light color, coordination and visual comfort. When designing, we must use a suitable light source to meet the requirements of energy saving.
(2) Select high-efficiency lamps
In addition to the need for decoration, high-efficiency lamps with high direct light flux ratio, reasonable light control performance, high reflection or transmission coefficient, and stable light distribution characteristics should be preferred; asymmetric light distribution lamps are used, which have the characteristics of reducing the reflection glare in the working area. Under certain illumination, the visual conditions can be greatly improved, so that higher performance can be obtained; lamps made of materials with slower metamorphism, such as glass lampshades and enamel reflectors, can be used to reduce the rate of light energy decay; The efficiency of the luminaire should not be lower than 70% (not less than 55% when equipped with a blackout grid), and the efficiency of outdoor luminaires should not be lower than 40% (the outdoor floodlight should not be lower than 55%).
(3) Reasonable lighting method
Appropriate use of general lighting, local lighting and hybrid lighting three ways, when a light source can not meet the requirements of illumination, etc., can use two or more sources of mixed lighting, which improves the light efficiency and improves the lighting quality. In the general working area, if the working surface density is not large, local lighting can be installed on the working surface to reduce the waste caused by the large-area increase of lighting fixtures; the high-intensity gas discharge lamp has the characteristics of large luminous flux. The way of lighting, so as to avoid the problem of uneven illumination and glare, and improve the quality of lighting to achieve energy-saving effects.
(4) Reasonable selection of illuminance standard value
When designing lighting, the illumination should be determined according to the needs of work and study. The illuminance value is reasonably determined according to the level of the building and the function of each room; the lighting power density value is determined according to the functional requirements of the lighting place. And should comply with the current national standards "architectural lighting design standards" GB50034-2004.
(5) Reasonable use of lighting control
Make full use of natural light, according to the change of illumination of natural light, the sub-components control the opening and closing of the lamps. Appropriately increase the lighting switch point during design, that is, the number of each switch control luminaire should not be too much for management and energy saving; for the lighting design of large-area places, the partition control mode is adopted, which can increase the flexibility of the lighting branch circuit control. It is beneficial to save electricity when the lighting is not turned on. If there are conditions, the electric lighting can be controlled by dimmers, time switches and power-saving switches. In public places, the lighting can be controlled by centralized control, and the automatic control device with delay can be installed. The rocker switch control can be set on the socket panel. When the electrical equipment is not used, it can easily cut off the power supply of the socket and eliminate the no-load of the equipment. Consumption, to achieve the purpose of saving electricity.
(6) Other lighting energy saving measures
Replace the inductive ballast with an electronic ballast, because the electronic ballast itself has a low power consumption of about 15% of the luminaire efficiency and 95% of the power factor, so it is essential in energy-saving design. . In addition, in the power distribution, try to make the load three-phase balance.
3 case analysis
3.1 Design principles
When we are designing, we can't blindly pursue high standards of illumination or blindly reduce the value of illumination for energy saving. Both of these consequences are wasteful. Designers should use realistic lighting density values â€‹â€‹for each building based on the user's perspective and development based on national lighting design specifications. Nowadays, some customary practices in lighting design are often not to use illuminance calculation. Simply use the power density value to calculate the number of lamps required. This method does not exceed the standard for the vast majority of indoor space, but the actual illuminance value. However, it exceeds the illuminance value specified in the standard, which is contrary to the actual energy-saving design principle. To this end, in early 2008, the Beijing Municipal Planning Commission issued the â€œBeijing Building Energy Efficiency Design Calculation Document Preparation Requirementsâ€ (Notification No.: Municipal Regulation  No. 112), which required the illumination of typical rooms to be listed in the construction drawing design. The power density calculation table (see Table 1) is used to regulate the design of lighting energy savings.