What is the case of energy-saving renovation of existing buildings in hotels?

What is the specific content of the case of energy-saving renovation of existing buildings in hotels? Zhong Da Consulting will answer your questions below.

20091October 26th, the National Development and Reform Commission issued "China's Policies and Actions in Response to Climate Change-Annual Report for 2009", which outlined the new progress in China's response to climate change since last year. At the same time, the government of China has also announced the action goal of controlling greenhouse gas emissions-by 2020, China's carbon dioxide emissions per unit of GDP will be reduced by 40% ~ 45% compared with 2005. Energy conservation and emission reduction will become the focus of the government's next stage. At present, there are more than 40 billion m2 of existing buildings in China, and the number of new buildings is increasing at a rate of 2 billion m2 every year. More than 95% of existing buildings are high-energy buildings, and even new buildings, less than 20% can meet the mandatory energy-saving standards formulated by the state. High-speed growth and high energy consumption make the construction industry a major energy consumer alongside industry and transportation. Building energy saving is the most effective means to reduce building energy consumption. At present, many cases of energy-saving buildings have been built in China, but the energy-saving benefits of these buildings are not obvious; Or lack of practicality, which hinders the large-scale promotion of building energy conservation. At the end of 2008, Yuanda Air Conditioning Co., Ltd. began to carry out energy-saving renovation of Yuanda City, and has completed the renovation of eight buildings [2]. This paper mainly introduces the Ark Hotel, the representative building of 1, and the energy-saving technology and unique air conditioning system applied in the renovation, and makes statistics on the energy consumption of air conditioning. Judging from the energy consumption of the reformed air conditioner, its energy saving rate has reached the standard of 6 L room. 1 Project Overview Ark Hotel was built in 1994, located in Yuanda City in the eastern suburb of Changsha, and is mainly used to receive important customers. The building is divided into four floors: basement 1 1 is the company's switchboard and auxiliary room; 1 ~ 3 floors are hotel rooms. The building area is 1 684 m2, and the air conditioning area is 1 420 m2. Before the renovation, the building envelope was mainly composed of 240 mm thick brick walls and aluminum alloy single-layer glass windows. The main air conditioner is a small non-electric air conditioner, and the room is a traditional fan-coil system, so there is no fresh air, which is mainly taken by opening the window. From 2006 to 2008, the energy consumption of Ark Hotel was counted. According to statistics, the fuel consumption of refrigeration and heating in Ark Hotel is 354 kW-h/m2 (converted into primary energy, the same below), the power consumption of power transmission and distribution system is 45 kW-h, and the total energy consumption of air conditioning system reaches 399 kW-h, which is a typical high-energy building. 2 Air conditioning load analysis According to the characteristics of the building envelope and air conditioning system before renovation, the air conditioning load of Ark Hotel is calculated by Hongye load software, and its air conditioning load ratio is shown in Figure 2. It can be seen that the envelope load and fresh air load account for 79% of the total air conditioning load, while the indoor heating value (personnel, equipment and lamps) only accounts for 2 1% of the air conditioning load. Building envelope and fresh air load become the main factors affecting building energy consumption. 3 transformation method and application technology In June 2008 +065438+ 10, Yuanda Air Conditioning Co., Ltd. carried out energy-saving transformation on Ark Hotel according to the analysis results of air conditioning load, which was mainly divided into two parts: envelope transformation and air conditioning system transformation. It is estimated that the energy-saving rate of air conditioning system will reach 80% after transformation. 3. 1 Building envelope reconstruction The building envelope mainly includes five parts: external wall, roof, window, external sunshade and external door. 3. 1. 1 renovation of external walls and roofs The total area of external walls and roofs of Ark Hotel is about 1 700 m2. No energy-saving measures were taken before the renovation, which is the main heat dissipation part of the building. In the reconstruction, a thin plastering external thermal insulation system was adopted, and 150 mm expanded polystyrene board was pasted on the original external wall, and the heat transfer coefficient was reduced to 0.24 W/ (m-2K). The roof adopts 100 mm expanded polystyrene board for external insulation, and the heat transfer coefficient is 0.34 W/(m2-K). 3. 1.2 Energy saving in windows is more important than energy saving in walls. The heat transfer coefficient per unit area of single-layer glass is generally 3 ~ 4 times that of ordinary wall. Therefore, the energy-saving of external windows should first reduce the heat transfer coefficient of windows. The original exterior windows of Ark Hotel are all aluminum alloy single-layer glass windows with a heat transfer coefficient of 6.2 W/(m2-K) and poor sealing performance. In the renovation of windows, the first thing is to reduce the window area. The total window area of the original building was 298 m2, but after renovation, the window area was only 75 m2, and the window-wall ratio was reduced from 25% to 6.3%. Secondly, all the original aluminum alloy single-layer glass windows are replaced with three-layer glass fiber reinforced plastic frame windows, argon is filled between glass partitions, and sealing strips are installed between window frames and glass. The heat transfer coefficient of the window is 1.65 W/(m-2K). 3. 1.3 Shading transformation Solar radiation enters the room through glass, which is one of the reasons for the high energy consumption of air conditioning. The ark hotel is east-west, and the windows are concentrated in the east-west, so solar radiation can directly enter the room, resulting in an increase in energy consumption of air conditioning. The building was originally equipped with internal sunshade, but it can't prevent the solar radiation heat from entering the room, and it is easy to be absorbed by sunshade components, so the heat insulation effect and energy saving potential are far less than those of external sunshade. In order to achieve the maximum energy-saving effect, external shading was installed outside the east and west three-story glass windows. The external shading is in the form of electric cloth roller blinds, which can adjust the shading area according to the outdoor weather conditions and the viewing needs of indoor personnel to control the solar radiation entering the room. For the south-facing external window, because the sun is oblique most of the time, it is only necessary to install a fixed sun visor to meet the requirements of shading in summer and heating in winter. 3. 1.4 Renovation of the Outer Door The original outer door of Ark Hotel was a single-layer glass sliding door with large heat transfer coefficient, and there was frequent indoor and outdoor air circulation when people often came in and out. In the transformation, the original canopy outside the gate was used to form a hall, and a layer of wooden door was added outside. The top and both sides of the ceiling are insulated with150 mm. The wooden door is specially made of 60 mm polystyrene board. The reformed gate consists of two doors, and the middle part forms a buffer zone as a transition zone, which effectively prevents the loss of cold energy. 3.2 Air conditioning system transformation In the load calculation, the fresh air load of Ark Hotel accounts for 46%, which is the maximum load. In order to ensure indoor air quality, fresh air is the most common phenomenon, which directly leads to the increase of energy consumption of air conditioning. 3.2. 1 In the transformation of air conditioning system, the original air conditioning system was completely dismantled and a new heat recovery fan and centralized coil system were adopted (as shown in Figure 9). An efficient heat exchanger is installed in the new heat recovery fan, and its heat exchange efficiency is 70% in summer and 90% in winter. The air treatment process in cool season is shown in Figure 10. After exchanging heat with the heat in the exhaust air through the heat exchanger, the outdoor fresh air is processed from the state point W to the state point W', and then mixed with some indoor return air to reach the state point C. The mixed air is finally cooled to 18℃ by the air conditioning coil and sent indoors, which is close to the dew point (17.6℃). The whole building adopts two new heat recovery fans, the fresh air volume is 1, 500m3 /h, and the fresh air exchange frequency reaches 1.5 times/h.3.2.2 The air conditioning load in the transition season is mainly indoor calorific value. When the ambient temperature is low, the envelope with low heat transfer coefficient can prevent indoor heat loss and reduce the heating demand. On the contrary, when the ambient temperature is different from the indoor temperature by several degrees, the envelope with low heat transfer coefficient is not conducive to internal heat dissipation, which leads to an increase in indoor temperature and requires refrigeration. This often happens in the transitional season and summer nights. Adopting a brand-new air system, the exhaust air does not exchange heat with outdoor fresh air, and directly uses outdoor low-temperature air as a natural cold source, which can achieve a good energy-saving purpose. Outdoor fresh air is introduced into the new heat recovery fan by the fan, the bypass valve in the new fan is opened, and the fresh air is directly sent into the room through the bypass valve; The exhausted air is directly exhausted through the heat exchanger under the action of the exhaust fan (as shown in figure 1 1). Fresh air and exhaust air will not be mixed through different paths to realize brand-new air. Because the fresh air does not pass through the heat exchanger in the new heat recovery fan, the fan resistance is reduced, and the fan air supply volume can reach 1.2 times the rated value. 3.2.3 Energy-saving control strategy of air-conditioning system The building automation system is installed in the whole air-conditioning system, and its control strategy is shown in Table 2. The control process is mainly to realize the linkage of the air conditioning host, the new heat recovery fan and the bypass valve by detecting the outdoor temperature. Take the fresh air mode as an example. When the outdoor temperature is 10 ~ 25℃, the air conditioner is turned off, and the fresh air recovery fan adopts fresh air mode. By tracking the exhaust air temperature, the fan frequency is adjusted to make the room temperature 18 ~ 26℃, which not only saves energy but also meets the indoor fresh air demand. In cooling or heating mode, the new heat recovery fan can control the volume fraction of CO2 in indoor air below 1 000- 10-6 by adjusting the fan frequency. 4 Benefit Analysis of Energy-saving Renovation The appearance of the renovated Ark Hotel is the same as that of ordinary buildings, but the operation of comprehensive energy-saving technology has brought great economic and environmental benefits.

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