Behind the rapid construction of Leishenshan Hospital, the second hospital dedicated to the treatment of patients with novel coronavirus pneumonia in Wuhan, the wisdom and strength of architects and engineers are condensed. As a temporary respiratory infectious disease hospital, how to ensure that the air-conditioning and ventilation design in the hospital provide a safe and comfortable medical and working environment for patients and medical staff, and how to avoid cross-infection caused by air circulation? How to set and select filtration, sterilization and purification devices in the ventilation system? HVAC engineers need to consider all aspects. The HVAC engineers of Zhongnan Architectural Design Institute who participated in the design of the Leishenshan Hospital will interpret for you how to design ventilation and air conditioning in this infectious disease hospital in a special period and under special conditions.

01   Background
On the occasion of the New Year's Eve in 2020, a sudden epidemic spread from Wuhan to the whole country. Life is more important than Mount Tai, and the prevention and control of the epidemic affects everyone's heart. Since the start of the anti-epidemic work, Zhongnan Architectural Design Institute has resolutely implemented the various work arrangements of the Party Central Committee, the Hubei Provincial Party Committee and the Provincial Government, and Zhongnan Design Group.The main leaders took the lead in establishing an emergency design response mechanism at the first time, and with the mission and responsibility of the state-owned enterprise compound, give full play to the advantages of design expertise, and go all out to participate in the fight against the epidemic. The epidemic is like a fire, and it is urgent. The HVAC design team of the Central South Hospital of Leishenshan Hospital received the task from the evening of January 24, started the drawing design, and began to accept it on February 5. It raced against time for 10 days and 10 nights without slack. Deliver all construction drawings in 3 days, cooperate with the construction on the project site throughout the process, break through the routine, and optimize the drawings in time according to the actual needs of the site until it is transferred to the stage of operation and maintenance cooperation services.

02   Introduction
The construction land area of Leishenshan Hospital is about 220,000 m2, and the total construction area is about 79,000 m2. The overall planning is designed in accordance with the standards of infectious disease hospitals, and is designed to treat patients diagnosed with pneumonia caused by new coronavirus infection. According to the land use, the east and west districts are planned as isolated medical areas and medical living areas respectively, and are equipped with relevant operation and maintenance rooms. The total number of hospital beds is 1,600 beds, which can accommodate about 2,300 medical staff. The total construction area of the isolated medical area is 52,200m2. It is a new one-storey temporary building with sanitary passage unit, ward nursing unit, medical technology unit, and reception area. The nursing unit is a container spliced building, the external dimensions (length × width × height) are 3m × 6m × 2.6m, and the indoor net height is 2.4m; the medical technology area is a steel structure prefab building with a building height of 4.5m. On the north side of the isolation medical area, there are sewage treatment stations, microwave disinfection rooms, temporary waste storage, waste incineration rooms, liquid oxygen stations, positive and negative pressure station rooms and other supporting facilities.
┃ Overlooking renderings of Leishenshan Hospital

┃ Overlooking the real picture of Leishenshan Hospital


03   Design Principles
Air conditioner design parameters
The design of the outdoor parameters of the air conditioner mainly considers the winter meteorological conditions in Wuhan during the outbreak and the expected climatic conditions. Referring to relevant national regulations, the interior design temperature of the main rooms in the ward area, medical care area, and medical technology area is 18-22 °C in winter, and the design temperature of the main patients and medical care passages is not lower than 18 °C. Air conditioning ventilation system
In order to avoid cross-infection, the main rooms in the ward area, medical care area, and medical technology area are equipped with heat pump type split air conditioners. The negative pressure inspection, negative pressure ICU, and negative pressure operating room of the medical technology area are operated with fresh air from the direct-expansion all-air purification air-conditioning unit, and the air supply duct is equipped with an electric heater. The electric heater is set to be adjusted in stages and take protection measures for no wind and power failure.
Germs that are floating in the air or attached to dust particles can attach to the coils of the air conditioning unit and are discharged with the condensed water, and these viruses can make people sick. Therefore, the condensed water of the air conditioner should not be separately discharged to the outdoors, but should be collected in a centralized manner in each area, and should be collected together with the sewage and wastewater discharge in each area.
In the design of ventilation and air-conditioning, we should strive to adopt orderly pressure gradient control measures to reasonably control the airflow direction. The pressure gradient settings in different pollution levels should comply with the principle of directional airflow organization, and ensure that the airflow changes from clean area to semi-polluted area to polluted area. direction flow. The medical and nursing area has a positive pressure relative to the infectious area. Control the negative pressure in the negative pressure isolation ward and negative pressure laboratory to avoid the intersection of clean air and polluted air, reduce the probability of mutual infection, effectively block the spread of the virus, and ensure the safety and health of medical staff. The minimum ventilation frequency in the negative pressure isolation ward is 12h-1, the minimum ventilation frequency in the polluted area is 6h-1, and the minimum ventilation frequency in the clean area is 3h-1.
All regional air supply systems are equipped with coarse, medium and high filtration to ensure the cleanliness of air supply. At the same time, effective air purification and disinfection measures should be taken to minimize the impact of exhaust air in negative pressure isolation wards and other polluted areas on the surrounding environment. The pressure difference detection and alarm devices are installed before and after the air supply filter unit and the exhaust air high-efficiency filter. When the pressure difference value exceeds the set value, the sensor alarms, and the equipment is replaced accordingly.

G2 Coarse Efficiency Filter

F7 Medium Efficiency Filter, H13 High Efficiency Filter

Equipment and Materials
In view of the short construction time and high requirements of the current emergency temporary hospital, and the supply of some equipment and materials does not meet the requirements of the construction period, it is our key consideration to do a good job in the design of HVAC according to local conditions. During the design process, the team sent special personnel to connect with major equipment suppliers, and tried to use mature and reliable equipment with large inventory, fast transportation, and donated equipment from manufacturers to save time for product procurement and delivery. At the same time, it is convenient for the construction unit to quickly install and debug. The selected ventilation and air-conditioning pipes meet the requirements of the construction period, are simple to manufacture and install, and have good air tightness. Through the above measures, the construction period has been greatly shortened on the premise of ensuring the reliable operation of the system.



┃ Some manufacturers donate equipment