A thorough understanding of the concept of green medical building is the prerequisite for good design. At home and abroad, there is no complete and unified definition of green medical building. From the connotation, green medical building belongs to the category of "green building", reflecting the basic characteristics of green building. Moreover, hospitals have their own specificity, which not only include elegant and comfortable, safe, reliable and harmless green environment, but also include green development strategy, green medical treatment and diagnostic services, green humanistic concept, green management and other aspects, i.e., energy saving and environmental protection are not at the expense of patients' recovery and health care personnel's work efficiency, but rather, they are the buildings with the most fundamental purpose of guaranteeing medical safety, preventing the spread of diseases and improving the level of health and wellness. level as the most fundamental purpose of the building group.
Theory of energy-saving technologies and microclimate design
What is a low-power and low-energy energy-efficient building? To design a building so that the indoor air temperature is maintained as close as possible to the comfort range throughout the year without the use of any heating or cooling equipment. The indoor air temperature of a building that only takes into account the influence of climatic conditions is called the free indoor temperature or the natural indoor temperature. The less time the free indoor temperature is outside the comfort range, the less energy is consumed and the less adjustment of the temperature difference is required. This is a clear indication of the primary task of heating and cooling equipment, which is to assist in adjusting the natural indoor temperature to within the comfort range. With the availability of local hourly weather data throughout the year, it is possible to calculate the free indoor temperature of any building to arrive at the time and magnitude of the necessary indoor temperature corrections throughout the year.
The requirement for energy efficiency can be found in hospital building design briefs and various competition documents. Not only that, but ease of maintenance is often included in the requirements, and in fact, there are many methods that have been used very effectively. For example, the use of fa?ade insulation wherever possible, the use of sun shading panels, double glazing and new non-condensing glazing products are also widely publicized. In addition to equipment and material factors, the building itself can also produce energy saving effects, which is the "self-regulating microclimate" of the stomach and lungs. The use of self-regulation of the building itself, the design of a good microclimate environment, involving a reasonable hospital site selection, master plan planning, layout, physical conception, sectional design, fa?ade design, detailed construction, greening and water landscape treatment and other aspects, such as multi-storey hospitals, combined with the layout of outdoor courtyards, which can greatly enhance the climate of the hospital building's own ability to adjust, and the formation of a good natural lighting and ventilation.
HVAC energy-saving professional design points
1 strengthen the management of designers, accelerate the implementation of equipment engineers registration system HVAC project, there should be a more detailed calculation of hot and cold loads and take some energy-saving measures
Currently, many designers are using the proposed budget indicators repeatedly increased, so that the cold, heat source hosts long-term in the low load, low efficiency.
2 HVAC indoor design temperature determination
By Chongqing, Shanghai, Guangzhou and other areas of practice has proved that the indoor temperature in summer is 1 ℃ lower or 1 ℃ higher in winter, in addition to the HVAC project's investment increased by 6%, the energy consumption increased by 8%, increase the indoor/outdoor temperature difference is not in line with the requirements of hygiene. Comfort air conditioning summer air conditioning summer more ideal indoor temperature is lower than the outdoor ambient temperature of 5 ℃ for good.
3 air conditioning hot and cold sources
Central air conditioning energy consumption generally includes three parts, air conditioning hot and cold sources; air conditioning machine end equipment; water or air delivery system. These three parts of energy consumption, cold and heat source energy consumption accounts for about half of the total energy consumption, is an important element of air conditioning energy saving. Considered solely from the point of view of energy consumption in summer refrigeration: centrifugal, screw chiller is the highest, steam two-effect LiBr absorption chiller is the smallest; winter heating: screw, piston heat pump chiller and water heater is the highest, the lowest electric water heater, that is, the highest energy consumption.
4 air-conditioning units and end equipment
Set fan air volume, air pressure should be selected to match the reasonable, less leakage, air delivery system number of large units. Fan coiler from the overall level of similar products abroad compared to about the same, but compared with the advanced level of foreign countries, the main gap is the power consumption, coiler weight and noise.
5 air-conditioning water system
General air-conditioning water system transmission and distribution of electricity, in the winter heating period accounted for about 20-25% of the power of the entire building power; summer cooling period accounted for about 12-24%, so the water system energy saving is of great significance. Selection of water pumps should be each water loop should be hydraulic balance calculation, the pressure difference between the circuit to take effective borrowing, to avoid hydraulic, thermal imbalance phenomenon. Designers should pay attention to the water system design, and actively promote frequency conversion speed pumps, winter and summer double-speed pumps and other energy-saving measures.
6 cooling tower
Refrigeration system cooling water inlet temperature of the host has an important impact on the power consumption, generally projected in the amount of water in a certain situation, the inlet temperature is higher than 1 ℃, the electric compression host power consumption increased by about 2%, lithium bromide water chiller fine energy consumption is 6% higher. At present, the main problems of domestic fiberglass cooling tower are as follows: low cooling efficiency, not up to the cold amplitude specified in the product samples. Drift water is serious, it not only pollutes the environment, but also a waste of water. Noise, noise affects the environment of the surrounding residents living.
7 strengthen the management of central air conditioning
Strengthen the training of air-conditioning operators, improve the quality of management personnel, the implementation of air-conditioning operators operating license system. Central air-conditioning system to implement independent power consumption accounting system. Overcome the power to eat "pot rice", to do waste of electricity penalty, saving electricity award system. In addition, it should be based on specific projects. Actively promote the water loop heat pump, the use of heat recovery, variable air volume, variable water volume system and other energy-saving technologies.
Green strategies for HVAC design of green medical buildings
1 Reasonable use of natural cooling and heating sources
Ground source heat pump is a kind of energy-efficient and environmentally friendly air conditioning system that utilizes shallow underground geothermal resources for both heating and cooling. It can realize the transfer of energy from low-temperature heat source to high-temperature heat source by inputting a small amount of high-grade energy. The use of ground source heat pump system, on the one hand, eliminates the boiler room, there is no combustion and exhaust gas, reducing greenhouse gas emissions and protecting the environment; on the other hand, using renewable geothermal heat as a source of cooling and heating, heating in winter and cooling in summer, which greatly reduces the power consumption of the traditional water chiller, and it is a low-carbon and energy-saving green technology. In addition, air source heat pump, sewage source heat pump, solar energy refrigeration is also a green measure that cannot be ignored. But these systems are not suitable for each project, must be based on the actual characteristics of the project to be weighed, compared, in the conditions allow the premise can be used.
2 rational use of ice storage technology
Ice storage technology can reduce the city's summer peak electricity load, with low temperature, small air volume of high-speed air supply, in general public **** building application has been very common, is an optimization of resource allocation, protection of the ecological environment of technological innovation, can produce good social and economic benefits. With the urban power supply tariff policy reform, the hospital electricity prices have also begun to implement peak and valley tariffs, cold storage technology is gradually implemented in the medical building. There are engineering examples of cold storage technology applied in hospital ward buildings, and will be adjustable fresh air volume associated with it, practice has proved that the effect of this green strategy is very obvious, can significantly save operating costs. Moreover, the use of ice storage system to the air conditioner 0 ℃ -3 ℃ low-temperature water, the use of low-temperature air supply, expanding the temperature difference between the air supply, reduce the amount of air supply, while reducing the delivery medium consumed by the pump energy, thus making up for the higher initial investment in the cold storage system, to improve the performance coefficient of the whole system.
3Reasonable use of natural ventilation
Reasonable natural ventilation is one of the strategies to realize the greening of the building, which can provide fresh air and achieve cooling in the transition season, and in the air conditioning cooling season can also be used at night ventilation, reducing the heat storage of the envelope and furniture, and reducing the next day's air-conditioning start-up load. Under the effect of indoor and outdoor wind and heat pressure, the use of natural ventilation can reduce the fan system and save electricity. Without the pollution of fan noise, the ward building appears more green and pleasant, more conducive to the patient's quiet recovery.
4 reasonable use of new energy-saving equipment
In the case of suitable conditions, the use of new energy-saving equipment can also play a multiplier effect. A hospital in Xinjiang, air conditioning area of 40,000 square meters, the project adopted a dry condition fan coil + independent air conditioning system, the new air using three-stage evaporative cooling air conditioning system; the cold source of indirect evaporative chiller; independent of the new air, the new air to bear the latent heat load and part of the sensible heat load, the temperature of the air can be up to 16 ℃, reducing the chiller's cold: due to the increase in the amount of fresh air, which improves indoor air quality, more suitable for patients to convalesce and recover. As the volume of fresh air increases, the quality of indoor air is improved, which is more suitable for patients' convalescence and recovery. At the same time, the indirect evaporation chiller improves the COP value of the cold source, and the dry operation of the fan coiler avoids the generation of condensate, eliminates the cost of condensation and dehumidification, and reduces the breeding of bacteria. Therefore, applying this pay-type energy-saving equipment is a good choice for realizing a green hospital.
5Reasonable air heat recovery
In the air conditioning load of ordinary public **** building, the fresh air load accounts for about 20%-30%, and medical buildings have higher air quality requirements, and the fresh air load is relatively larger. Therefore, the use of residual cold or heat in the exhaust air in medical buildings to treat fresh air, reduce the fresh air load, reduce the energy consumption of fresh air treatment, and improve the economy of air conditioning system has become an important way of energy saving in green medical buildings. Different functional areas in the hospital have different levels of cross-contamination risk, and in terms of risk size, the outpatient clinic is the largest, the medical technology is smaller, and the ward is the smallest. It is important to choose reasonable air heat recovery devices for functional areas with different risks. Therefore, when designing the air heat recovery system for medical buildings, not only should the heat exchange efficiency of the heat recovery device be strictly controlled, but also its structure, material, leakage rate, cleaning surface, head-on wind speed, etc., should be strictly required, and pressure control should be utilized to reduce the risk of cross-contamination. As long as the design is reasonable and appropriate, the use of air-to-air heat recovery technology is a green strategy for achieving energy efficiency in medical buildings.
Green medical building both medical building and green building dual identity, the construction of green hospital has an extremely deep and wide connotation and extension, far beyond the building indoor and outdoor scenery of the blend, natural lighting and ventilation, solar energy utilization and other ideas. Further innovation of design means and design strategy, need the continuous efforts of all professional designers, HVAC design in the green medical building in the road ahead is a long way to go.
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