Energy saving and economic benefit evaluation of t

Energy saving and economic benefit evaluation of intelligent building

Abstract: This paper analyzes the energy-saving problems of intelligent building from the aspects of building sustainable development strategy, engineering technology recording and economic analysis of output control signal value, discusses the content and method of energy-saving benefit evaluation, and puts forward the calculation method of energy-saving coefficient of air-conditioning system, combined with the intelligent project example of Beilun port international container terminal complex building of Ningbo Port Authority. Energy conservation and economic benefit evaluation of intelligent buildings

key words: Untitled Document of energy conservation benefits of intelligent buildings

1 energy consumption profile of commercial buildings

according to relevant statistics, the energy consumption of air conditioning, lighting, elevators and other systems in commercial buildings such as office buildings and hotels is roughly as follows: ① air conditioning: the average proportion of air conditioning energy consumption of office buildings in the total energy consumption is 60%, the lower limit is 50%, and the upper limit is not higher than 70%; The energy consumption of hotel HVAC (heat, ventilation and air conditioning control) accounts for 44% of the total energy consumption. ② Lighting: the lighting energy consumption of office buildings accounts for 23% - 55% of the total energy consumption, with an average of 26%; The energy consumption of hotel lighting accounts for 29% of the total energy consumption. ③ Elevator: energy consumption of office buildings France introduced high-strength epoxy resin composites, accounting for 8% of the total energy consumption, and the energy consumption of hotel elevators accounts for 10% of the total energy consumption

2 energy saving measures for intelligent buildings

2.1 improve the accuracy of indoor temperature and humidity control

the change of indoor temperature and humidity is closely related to building energy conservation. According to the statistics of the National Bureau of standards, if the set point temperature is reduced by 1 ℃ in summer, the energy consumption will increase by 9%. If the set point temperature is increased by 1 ℃ in winter, the energy consumption will increase by 12%. Therefore, controlling indoor temperature and humidity within the accuracy range of the set value is an effective measure for air conditioning energy saving. Europe and the United States and other countries require indoor temperature and humidity control accuracy: the temperature is ± 1.5 ℃, and the humidity is 60 ± 5%

due to the absence of building automation system in traditional buildings, the room temperature is often supercooled in summer (lower than the standard setting value) or overheated in winter (higher than the standard setting value). This is not only inappropriate for human health and comfort, but also a waste of energy. The intelligent building with building automation system can not only automatically adjust the indoor temperature and humidity according to the setting, but also change the setting of indoor temperature according to the outdoor temperature and humidity and seasonal changes, so as to make it more meet people's needs and give full play to the function of air conditioning equipment. The higher the temperature control accuracy of the air conditioning system, the better the comfort and the more obvious the energy saving effect

2.2 fresh air volume control

according to health requirements, everyone in the building must ensure a certain amount of fresh air. However, too much fresh air will increase the energy consumption of fresh air. Taking Hotels in Shanghai as an example, under the design conditions (outdoor temperature in summer is 26 ℃, relative temperature is 60%, room temperature in winter is 22 ℃, and relative humidity is 55%), the cooling capacity required to process a kilogram of outdoor fresh air is 6.5kwh. Because the material has a high density heat of 12.7kwh, on the premise of meeting the requirements of indoor hygiene, reducing the fresh air volume has a significant energy-saving effect

the fresh air volume should be determined according to the indoor allowable CO2 concentration, which is generally 0.1% (1000ppm). It is not accurate to adopt the method of fixed fresh air volume, because with the change of season and time and the air pollution, the CO2 concentration in the outdoor air changes, and the change of indoor personnel naturally changes the demand for fresh air, so the most reasonable way is to automatically adjust the fresh air volume according to the CO2 concentration in the indoor or return air, so as to ensure the freshness of indoor air, The building automation system with perfect control function can meet these control requirements

2.3 optimal start and stop control of electromechanical equipment

for offices, shopping malls and other buildings, air conditioning is not required at night. Naturally, it is not necessary to turn on the air conditioning at night. In order to ensure the comfort of the indoor environment at the beginning of the work, it is necessary to precool and preheat the building in advance. In addition, the indoor temperature is a controlled object with great inertia. Turning off the air conditioning in advance can also ensure that the indoor temperature does not change much within a certain time, Through the calculation and control of the optimal start and stop time of air conditioning equipment, building automation system can shorten the unnecessary start and stop tolerance time of air conditioning on the premise of ensuring the comfort of the environment, so as to achieve the purpose of energy conservation; At the same time, when precooling and preheating, closing the outdoor fresh air valve can not only reduce the equipment capacity, but also reduce the energy consumption of cooling or heating caused by obtaining fresh air

in commercial buildings, the energy consumption of lighting accounts for a large part of the whole energy consumption, among which public lighting is the most prone to energy waste. The implementation of timing switch control for these lighting devices, and even the pre-set dimming control and window dimming control according to the work and rest time and outdoor light, can greatly reduce the energy consumption

in areas where various electricity prices are implemented, building automation system can be used to remove some relatively unimportant electromechanical equipment to reduce peak load, or put emergency generator into operation and release stored cooling capacity during peak power consumption by cooperating with ice storage equipment and emergency generator, so as to realize peak avoiding operation and reduce operating costs

2.4 air conditioning water system balance and variable flow management

the energy-saving control algorithm of air conditioning system is the core of intelligent building energy conservation. Through scientific and reasonable energy-saving control algorithm, not only the automatic control of temperature environment can be achieved, but also considerable energy-saving effects can be achieved

the essence of heat exchange in air conditioning system is that a certain flow of water exchanges energy with the fan driven supply air flow through the surface cooler. Therefore, the efficiency of energy exchange is not only related to the influence of wind speed and surface cooler temperature on thermal efficiency, but also related to the flow of cold and hot water supply and thermal efficiency. Usually, when effective air conditioning water supply system balance and variable flow management are not adopted for the air conditioning system, the conventional practice is to set the air conditioning control algorithm in the way of constant supply and return water pressure difference, resulting in poor temperature and humidity control accuracy and energy wave. 2. Pressing the "calibration" key is also extremely obvious. This is because under the constant supply and return water pressure difference, the self balancing ability is very poor, and the flow value is far from the actual heat exchange demand, which often leads to out of control temperature and humidity, energy waste and equipment damage

through the measurement parameter analysis of the flow and control effect of the air conditioner at the farthest end and the nearest end of the air conditioning system (relative to the water collector for the supply and return of the air conditioning system) under different energy supply states and different operation states, it can be seen that the air conditioning system has obvious dynamic characteristics. In the operation state, the building automatic control system