1. 1 general layout of the building (1): On the basis of realizing the building function, make full use of the sunshine in winter, avoid the dominant wind direction in winter, and use the natural ventilation in the cool period in summer to save energy in winter and summer. At the same time, the general layout should also consider the environmental impact in the building complex, such as the odor of the garbage transfer station, the burning smoke of the boiler room, the exhaust gas of the underground garage, the electromagnetic radiation of the substation and the noise of the surrounding traffic. , and reasonable layout of public and auxiliary facilities, to minimize the impact of pollution inside and outside the area. (2) Orientation: The main orientation of the building should choose the best orientation of this area. The main measure is to keep a proper amount of sunlight indoors in winter and minimize direct sunlight in summer. As far as Shanghai is concerned, it is necessary to reduce the east-west sunlight on buildings. The best orientation in different regions is slightly different. Shanghai due south to southeast 15, Beijing due south to southeast within 30, Guangzhou due south to southwest 515.

(3) Ventilation: The architectural layout has a great influence on the natural ventilation of the whole building complex. Generally speaking, staggered, oblique and freestyle building group layout is better than determinant and perimeter, and the wind resistance of buildings is small. The natural ventilation of single building has an important relationship with the location and opening area of external windows, which can lead the dominant wind into the room in summer and avoid the cold wind blowing directly into the room in winter. For some specific projects, professional wind environment simulation software can be used to simulate winter, summer and transitional seasons respectively to meet the requirements of ecological energy conservation. (4) Daylighting: Daylighting is not only affected by the area and location of the window, but also blocked by tall buildings in the area. The individual height in the building complex should be set in the pattern of high in the north and low in the south, so as to ensure that the whole window sunshine above 1h can be obtained from the winter solstice.

The shape coefficient of 1.2 has significant influence on building energy consumption. According to the statistics of hot summer and cold winter areas, if the shape coefficient is reduced from 0.4 to 0.3, the heat transfer loss of the envelope can be reduced by 25%, and the annual energy consumption of heating and air conditioning can be reduced by about 13% [2]. According to the characteristics of the corresponding building, it is suggested that the large concave and convex of the external wall should be reduced as much as possible without affecting the use function of the building, and the shape coefficient should be controlled as much as possible, which meets the strong requirements of national and local energy-saving design standards for public or residential buildings.

1.3 Building envelope The thermal design of buildings in China is divided into five areas: severe cold, cold in summer, cold in winter, hot in summer and warm in winter, and mild. The energy-saving potential of envelope structures in different regions is different, and the energy-saving contribution ability of envelope structures such as windows, exterior walls and roofs is also quite different. Therefore, the key points should be grasped when evaluating the energy saving of the envelope structure. For example, in hot summer and warm winter areas, the contribution rate of energy saving of envelope structure is external window > external wall > roof, and the focus of energy saving design is to consider the shading of external window first; In hot summer and cold winter areas, the order is external wall > external window > roof, and the focus of energy-saving design is first embodied in external wall insulation.

The energy assessment report shall clearly explain the thermal performance of area ratio of window to wall, windows, outdoor shading and roof greening, and clarify the thermal insulation practices of the envelope structure, the thermal performance of materials and the corresponding energy-saving technical measures. At the same time, the rationality and accuracy of the thermal calculation formula and results in the design text should be evaluated. In addition, the safety performance of fireproof materials should also be considered. In view of the thermal design index proposed in the text of the scheme design stage, it should be checked according to the corresponding energy-saving design standards of public buildings and residential buildings in this area. If some thermal performance indexes of the envelope can not fully meet the indexes specified in the current energy-saving standards, it needs to be weighed and judged according to the calculation software approved by the national construction administrative department; For the thermal design indicators that may be missing in the scheme text, clear compliance requirements should be put forward during the evaluation.

2 Analysis of the main points of performance evaluation of main building energy equipment system

Energy-saving design of energy-consuming equipment system in civil buildings is an important content to realize low-energy operation of buildings. At present, the evaluation content of energy-consuming equipment in HVAC, electrical system and other major buildings is relatively small, mainly staying in the description content consistent with the scheme design text, and there are few clear equipment energy efficiency indicators and quantitative energy consumption index estimation results, which can not provide reference for future building energy consumption monitoring. 2. 1 HVAC system HVAC system is a large energy consumer in buildings, and the load of HVAC equipment in various civil buildings accounts for about 43% ~ 52% [3]. According to the monitoring and statistical results of energy consumption of large public buildings in Shanghai, the energy consumption of HVAC accounts for about 40% ~ 60% of the total energy consumption of buildings [4], so it is not difficult to see that the energy-saving design of HVAC system is very important.

2. 1. 1 evaluation points The main evaluation contents of HVAC system should include indoor and outdoor design parameters, cold and heat source system, transmission and distribution system, air conditioning terminal equipment, etc. When evaluating energy efficiency, it should be clear that the indoor and outdoor design parameters are in conformity with the building energy-saving design standards in this area; Analyze the applicability of air conditioning forms and architectural properties; Analyze the rationality of cold and heat source selection and capacity allocation, and whether the residual heat and energy resources in the region can be utilized. The main energy efficiency indexes of cold and heat source equipment include EER, COP and boiler thermal efficiency of chillers and air conditioners. Analyze the conformity between the transportation system and the architectural features, and make clear or suggest the energy efficiency indexes such as the transportation energy efficiency ratio of water system, the power consumption per unit air volume of fans, and the insulation measures of water pipes and air ducts. Analyze the applicability of air conditioning terminal equipment selection, the rationality of air supply temperature, and the feasibility of air supply and return air mode.

2. 1.2 energy consumption estimation method of air conditioning system Generally, there are three methods for energy consumption estimation of air conditioning system: load index method, empirical data method and equipment power method. The load index method is mainly estimated by the cooling and heating load index per unit air conditioning area and the energy efficiency index (COP, IPLV) of refrigeration equipment. The rule of empirical data is to estimate and accumulate item by item according to the monitoring statistical data of electricity consumption of each unit of building air conditioning system released publicly in recent years in this area; The law of equipment power is estimated by combining demand coefficient and load coefficient under the condition of fixed equipment selection and clear power. From the results of actual building operation monitoring, the accuracy of the first two estimation results is better than the latter. However, as far as the evaluation period is concerned, many projects are still in the stage of scheme design, and the equipment selection is not clear. Therefore, it is suggested to combine the load index method with the empirical estimation method to ensure the accuracy and credibility of the estimation results as much as possible.

An example of estimating the energy consumption of air conditioning in a large public building in summer is as follows: a building is the headquarters building of an international enterprise in Shanghai, and the air conditioning system in the office area adopts a centralized central air conditioning system with chillers and cooling towers. The energy consumption of air conditioning system in summer mainly includes the energy consumption of air conditioning host (cold source equipment), conveying system equipment (wind and water) and terminal equipment (fan coil unit, new fan, etc.). ). The cold source adopts two screw chillers, and the COP value is not less than 5.1w/w. The cooling load per unit area of the building office area is 120W/m2, the office area is 2 1784.0 1m2, and the average load factor of the air conditioner is 0.6 ~ 0.77. Energy consumption of air-conditioning main unit e = 0.7×120× 21784.01/5.1×120× 8×10-7 = 344,400 kw. K: The ratio of total power consumption of air conditioning system equipment to power consumption of refrigeration unit in summer is about 1.8 ~ 2.0. The data comes from the measured values of many practical projects. Summer in E office of this project = K E mainframe (K in this project is1.8) =1.8× 34.44 = 61.99 million kW h2.2 The focus of energy evaluation of electrical system is the rationality of energy-saving design of power supply and distribution system, which is mainly analyzed from the following aspects. 2.2. 1 Substation shall be located in the load center to reduce the line length and line loss on the low voltage side. In addition, the influence of noise and electromagnetic radiation on the surrounding environment should also be considered when setting up the substation.

2.2.2 Verification of accuracy of load calculation Under normal circumstances, the whole process of power load calculation is rarely clear in the scheme text. Therefore, the load data in the scheme text should be checked when it can be evaluated. On the basis of selecting reasonable unit load index calculation, the optimal load coefficient method should be adopted to determine the transformer capacity, so as to ensure the safety and reliability of the system and the economical operation.

2.2.3 When evaluating the reasonable performance of transformer selection, it should be suggested to give priority to the selection of transformers with high efficiency, low power consumption and low noise, so as to make the actual load of the transformer close to the designed optimal load, improve the technical and economic benefits of the transformer and reduce the energy consumption of the transformer. 2.2.4 Power transmission and transformation loss estimation Power transmission and transformation loss is an important part of energy-saving evaluation of electrical system and an indispensable part of building electricity. Power transmission and transformation losses include variable losses and line losses. Usually, the simplified formula can be used to estimate the variable loss in building engineering, but if the traditional simplified formula in Electric Power Design Manual is followed (δ P = 0.02 SJS, δ Q = 0. 1 SJS).

Based on the energy-saving evaluation training materials of the National Development and Reform Commission, it is suggested that the determination of active and reactive losses of high-efficiency energy-saving transformers can be calculated according to the following simplified formula after checking by mathematical operation [5]: active loss δ P = 0.01sjs; Reactive power loss Δ q = 0.07 sjs. Because the line loss is related to the choice of cable length and cross section, it is often difficult to determine in the scheme stage, so in the energy evaluation stage, it can be estimated approximately according to "line loss ≈ 1.0 ~ 1.2 variable loss", and the sum of the two is the total power loss of the power transmission and transformation system. The results can also be obtained according to GB/T 16664 "Energy-saving Monitoring Method for Power Supply and Distribution System of Enterprises".

2.2.5 Energy-saving evaluation of lighting system The lighting power consumption of civil buildings accounts for about 25% ~ 35% of the total energy consumption of buildings [6], and there is often serious energy waste in the lighting of public buildings and residential buildings. Therefore, from the perspective of building energy saving, lighting has certain energy saving potential. The energy consumption of lighting system is mainly affected by the power of lighting equipment and the service time of equipment. The evaluation of lighting system can be mainly considered from the following aspects: (1) ensuring the rationality of the design of lighting power density value that meets the energy-saving index specified in the building lighting design standard; (2) The rationality of lighting control system design, which can reduce the lighting waste in public areas by realizing automation and intelligence of control mode; (3) Rationality of lighting source and lamps selection. Under the premise of ensuring lighting quality, try to use efficient and energy-saving lighting products, which can not only reduce the energy consumption of lighting system, but also reduce the energy consumption of air conditioning system.

3 Analysis of key points of energy consumption estimation

The estimation result of total energy consumption is the quantitative embodiment of building energy-saving design and the basis of total energy consumption control in the project area. The building energy consumption mentioned in the energy assessment report refers to the building energy consumption in a narrow sense, that is, the annual energy consumption of equipment after the building is put into use. The energy consumption categories of civil buildings are relatively simple, mainly including electricity, water and gas. For buildings that use central heating, central cooling and waste heat resources, input heat and cooling capacity should also be considered in energy consumption estimation.

3. 1 the electricity consumption of electric buildings can usually be estimated by unit index method or unit area power method. The unit index method is suitable for buildings (groups) with different functional properties or different functional units in the same building (group), such as commercial buildings and mixed residential quarters. The unit of electricity consumption index is usually W/ household, W/ station, W/m2, etc. For example, office buildings can be calculated as 30 ~ 70W/m2, and commercial buildings can be calculated as 60 ~120w/m2 [3]; For another example, according to the construction area of new residential buildings in Shanghai, the electricity consumption index can be 8kW/ household and 12kW/ household respectively, and the super-large residential buildings and villas can be 80W/m2 and100 W/m2 respectively [7].

The power per unit area rule is to classify and estimate different electric loads in buildings, and accumulate them item by item, such as lighting, sockets, elevators, water supply and drainage, ventilation, air conditioning equipment, etc. The corresponding load index can be reasonably selected by referring to the national technical measures for energy saving in civil building engineering design-electrical and building lighting design standards. The unit index method and the unit area power method can be used separately or in combination. The former is more suitable for the scheme design stage, especially for the construction project with only architectural scheme and incomplete professional scheme of public and auxiliary equipment, and the estimation result is relatively accurate. The latter is more suitable for estimating the electricity consumption of a class of load equipment in a certain building, and it is more accurate in the use time of specific equipment. This method conforms to the principle of building energy consumption measurement, and its results can be verified in future building energy consumption monitoring.

The formula for estimating power consumption is as follows: Wy = AAV PC TN (1), where Wy is the annual power consumption,10000 kW h; ; Aav is the annual average active load coefficient, generally 0.7 ~ 0.75; Pc is active power, kw; Tn is the actual working time of one year. In addition, the total electricity consumption of the building should also include the power loss in the power supply system, that is, transformer loss and power supply line loss. 3.2 Water consumption of buildings related to water is usually reflected in the scheme design text, but the results should be checked and used when it can be evaluated. Supplement and improve the types of water used in construction projects, including greening, road sprinkling, underground garage flushing water, air conditioning make-up water, etc. At the same time, it is suggested to adopt the water-saving quota index in GB 50555-2010+00 "Design Standard for Water-saving in Civil Buildings".

3.3 The units that use gas in civil buildings are mainly kitchens, canteens and boiler rooms. At present, most of the gas used in China is urban natural gas, artificial gas or liquefied petroleum gas. As far as housing is concerned, the residential gas is usually single-family gas cookers and gas water heaters, and the rated gas flow is usually 2.5m3/h. The residential gas consumption can be estimated according to the actual daily use time of the family, or the residential gas consumption index in the statistical yearbook of the project location can be adopted. For example, according to "Table 5.4- per capita energy consumption in major years" in Shanghai Statistical Yearbook 20 12, the annual average domestic gas consumption index in Shanghai in 201year is: natural gas 37. 12m3/ person a, and gas 23.6000.000000000005 For large public buildings, boiler room is usually used as the heat source of central air conditioning system and domestic hot water system. When estimating the gas consumption of boiler room, it is necessary to estimate the annual heat consumption of air conditioning and domestic hot water system first, and then calculate the annual gas consumption of boiler room according to the heat loss rate of pipe network, boiler thermal efficiency and gas calorific value. As for the gas consumption of commercial restaurants in large public buildings, we can make an analogy analysis and estimation by investigating the data of commercial gas consumption of similar buildings in the same area.

4 Benchmarking Analysis of Building Comprehensive Energy Saving Level

The comprehensive energy-saving level of buildings is a benchmark to measure the energy-saving design of buildings. Because the energy evaluation of a building project basically belongs to the scheme design stage, there are some changing factors in the corresponding scheme, and the thermal performance index of the building envelope is not clear. Therefore, it is difficult to implement the trade-off calculation between the design building and the reference building, and the energy efficiency index of the architectural design energy saving rate is also unclear. In view of this, the building energy efficiency indicators referred to in energy assessment are usually quantitative indicators such as comprehensive energy consumption per unit building area (kgce/m2), electricity consumption per unit building area (kW h/m2), water consumption per unit building area (m3/m2) and itemized energy consumption per unit building area (kW h/m2, air conditioning, electricity, lighting, etc.). ). Although equivalent values are used in the classification of energy assessment documents, at present, China's statistical departments all use equivalent values when counting the total energy consumption in the region. Therefore, for the consistency of benchmarking platform, the building energy efficiency index should use the equivalent value data in the energy assessment report, and the impact of project energy consumption on regional energy consumption increment should also be implemented according to the equivalent value.

When benchmarking the energy efficiency level of civil building projects, we should first distinguish between public buildings and residential buildings. For example, by the end of 20 10, the energy consumption of public buildings and residential buildings in Shanghai was 49.24kgce/m2 and13.94 kgce/m2 respectively [9]. In the actual energy assessment, the energy consumption levels of different types of public buildings are quite different, and the high-end communities in residential buildings are also quite different from ordinary houses. The assessment projects often integrate multiple functional types. Therefore, it is not appropriate to conduct general benchmarking of building energy efficiency level, but to conduct independent analysis according to different types of buildings or regions such as offices, businesses, schools, medical care and hotels, and the corresponding benchmarking values can be obtained from local statistical survey data or literature.

5 conclusion

Since the implementation of 20 10 Interim Measures for Energy Conservation Assessment and Review of Fixed Assets Investment Projects (Order No.6 of the National Development and Reform Commission), energy assessment, as an important measure to "adjust and optimize the industrial structure and reasonably control the total energy consumption" [10], has developed rapidly in various provinces and cities, providing a positive and effective reference for the decision-making of government investment departments, but at the same time, due to the energy assessment work, In recent two years, the National Energy Conservation Center has also issued 20 10 and 20 1 1 annual energy assessment guidelines. However, the content, depth and quality of energy assessment reports are uneven in actual work. Overall, the preparation level of energy assessment reports in various places is slowly improving. In this paper, starting with the important concerns in the process of compiling and reviewing energy assessment, such as "building energy-saving design, building energy equipment system, total energy consumption classification and estimation, and energy efficiency index benchmarking", the specific actual compilation process is emphasized, hoping to provide some reference and guidance for the vast number of energy assessment workers.

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