Investigation and Analysis on the Current Ventilation Situation of A General Hospital--Boxing Motexo Industries Co.,Ltd The functions and meanings of ventilation system in hospital are introduced with its design and pitfalls in operation and management ana-lyzed. Based on the investigation and analysis of the indoor air condition in a general hospital, it shows that the indoor air condition is universally terri- ble with high dust density and dissatisfactory rate of indoor disinfectant fluid smell and sick smell over 50%. Ventilation improvement relies not only on ventilation system and technology, but also governmental regulation on hospital ventilation design. Key words: hospital; ventilation system; subjective investigation; healthy ventilation; thermal comfortable ventilation; air pressure gradient; variable air volume system; constant air volume system

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Introduction
Under the situation of vigorously promoting green and low-carbon buildings,
my country has greatly improved the design requirements of residential and public
buildings. The indoor and outdoor wind environment of buildings has become one
of the important indicators for evaluating the greenness of buildings. For buildings,
the ventilation effect directly affects the comfort of the human body, and at the same
time, it also has a certain degree of impact on the energy consumption of the
building. Therefore, reasonable ventilation design is one of the effective means to
improve the greenness of the building and reduce the energy consumption of the
building.
As a regional or regional medical center, a general hospital is responsible for
many functions such as medicine, teaching, research, prevention, health care, and
health consultation. As a unique type of public building, the hospital has its own
unique features compared with general public buildings. , Hospitals are generally
large in scale, with mixed flows of people and logistics, large numbers of people for
diagnosis and treatment, complicated types of diseases, and complicated medical
procedures. The quality of the ventilation environment will not only directly affect
the people in the hospital, but may even cause cross infection of germs. Therefore,
the design of the ventilation system for special public buildings such as hospitals is
particularly important.
1 Hospital ventilation system
Ventilation system is a kind of building environment control method to
control the spread and harm of air pollutants by means of ventilation dilution or
ventilation elimination, and to achieve indoor and outdoor air environment quality
assurance. A complete set of devices including air inlets, exhaust outlets, air supply
ducts, fans, cooling and heating, filters, control systems and other auxiliary
equipment. The main functions and meanings of the ventilation system in the
hospital are as follows.
1.1 Function of the ventilation system
The hospital ventilation system has two functions.
One is healthy ventilation --- use outdoor fresh air to renew indoor dirty air and
keep indoor cleanliness to a certain level; the other is thermal comfort ventilation ---
use indoor and outdoor temperature difference and humidity The amount is
different, and the indoor waste heat and humidity are eliminated to achieve the
purpose of cooling and dehumidification.
1.2 Significance of ventilation system
Comprehensive hospitals have the following characteristics: large area,
complex internal layout, often forming large-area building inner areas, and cold
supply in winter; numerous departments and different departments have different
requirements for equipment and environment, such as surgery department, CT
room, ICU Wards and central supply rooms; susceptible persons are highly
concentrated, and multiple disease sources coexist; continuous operation, 24 hours a
day without interruption, need to provide services for patients in all directions and
around the clock. In view of this, the ventilation system of a general hospital is of
great significance.
(1) Guarantee indoor air quality: provide fresh air, dilute and remove odor
suspended bacteria dust and hazardous chemical and radioactive material pollution.
(2) Ensure the safety of indoor air: air organization plays an important role in
preventing cross-infection. There are strict requirements on the direction of air flow
between different departments and operating rooms, and the air gradient pressure
difference is controlled to maintain the most suitable for medical procedures. Health
and environmental safety.
(3) Reduce the energy consumption in the later operation: reduce the heat and
cold loss of unorganized infiltration, and reduce the air conditioning time.
(4) Convenient operation and management in the later stage: According to the
actual demand air volume of the room, unified and centralized control and
management are carried out to reduce operating costs, energy saving and
environmental protection.
2 The status quo of indoor air quality in hospitals
When it comes to the air quality in the hospital, the first thing that comes to
mind is the pungent smell of disinfectant in the hospital. Generally, after staying in
the hospital for a period of time, I often feel dizzy, bloated, chest tight and other
uncomfortable symptoms. This environment will directly affect the patient’s mood
when visiting a doctor. It is very easy for patients to complain about the lax attitude of
the medical staff, depression, and low work efficiency. The following will subjectively
and objectively evaluate the air quality of a tertiary A general hospital. Investigation
and analysis of the status quo.
2.1 Hospital overview and survey methods
Ｉｎｖｅｓｔｉｇａｔｉｏｎ ａｎｄ Ａｎａｌｙｓｉｓ ｏｎ ｔｈｅ Ｃｕｒｒｅ
Abstract: Ｔｈｅ ｆｕｎｃｔｉｏｎｓ ａｎｄ ｍｅａｎｉｎｇｓ ｏｆ ｖｅｎｔｉｌａｔｉｏｎ ｓｙｓｔｅｍ ｉｎ ｈｏｓｐｉｔａｌ ａｒｅ ｉｎｔｒｏｄｕｃｅｄ ｗｉｔｈ ｉｔｓ ｄｅｓｉｇｎ ａｎｄ ｐｉｔｆａｌｌｓ ｉｎ ｏｐｅｒａｔｉｏｎ ａｎｄ ｍａｎａｇｅｍｅｎｔ ａｎａ－
ｌｙｚｅｄ． Ｂａｓｅｄ ｏｎ ｔｈｅ ｉｎｖｅｓｔｉｇａｔｉｏｎ ａｎｄ ａｎａｌｙｓｉｓ ｏｆ ｔｈｅ ｉｎｄｏｏｒ ａｉｒ ｃｏｎｄｉｔｉｏｎ ｉｎ ａ ｇｅｎｅｒａｌ ｈｏｓｐｉｔａｌ， ｉｔ ｓｈｏｗｓ ｔｈａｔ ｔｈｅ ｉｎｄｏｏｒ ａｉｒ ｃｏｎｄｉｔｉｏｎ ｉｓ ｕｎｉｖｅｒｓａｌｌｙ ｔｅｒｒｉ－
ｂｌｅ ｗｉｔｈ ｈｉｇｈ ｄｕｓｔ ｄｅｎｓｉｔｙ ａｎｄ ｄｉｓｓａｔｉｓｆａｃｔｏｒｙ ｒａｔｅ ｏｆ ｉｎｄｏｏｒ ｄｉｓｉｎｆｅｃｔａｎｔ ｆｌｕｉｄ ｓｍｅｌｌ ａｎｄ ｓｉｃｋ ｓｍｅｌｌ ｏｖｅｒ ５０％． Ｖｅｎｔｉｌａｔｉｏｎ ｉｍｐｒｏｖｅｍｅｎｔ ｒｅｌｉｅｓ ｎｏｔ ｏｎｌｙ ｏｎ
ｖｅｎｔｉｌａｔｉｏｎ ｓｙｓｔｅｍ ａｎｄ ｔｅｃｈｎｏｌｏｇｙ， ｂｕｔ ａｌｓｏ ｇｏｖｅｒｎｍｅｎｔａｌ ｒｅｇｕｌａｔｉｏｎ ｏｎ ｈｏｓｐｉｔａｌ ｖｅｎｔｉｌａｔｉｏｎ ｄｅｓｉｇｎ．
Key words: ｈｏｓｐｉｔａｌ； ｖｅｎｔｉｌａｔｉｏｎ ｓｙｓｔｅｍ； ｓｕｂｊｅｃｔｉｖｅ ｉｎｖｅｓｔｉｇａｔｉｏｎ； ｈｅａｌｔｈｙ ｖｅｎｔｉｌａｔｉｏｎ； ｔｈｅｒｍａｌ ｃｏｍｆｏｒｔａｂｌｅ ｖｅｎｔｉｌａｔｉｏｎ； ａｉｒ ｐｒｅｓｓｕｒｅ ｇｒａｄｉｅｎｔ； ｖａｒｉａｂｌｅ
ａｉｒ ｖｏｌｕｍｅ ｓｙｓｔｅｍ； ｃｏｎｓｔａｎｔ ａｉｒ ｖｏｌｕｍｅ ｓｙｓｔｅｍ
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2. Survey indicators Dissatisfaction rate%
Hot and cold feeling 39.51
Blowing feeling 29.63
comfortability 45.68
Disinfectant 55.56
Smell 62.96
Tiredness, headache 41.98
Allergic itching 22.22
noise 83.95
Particle size ≥0.3μm ≥0.5μm ≥1μm ≥3μm ≥5μm ≥10μm
Average value
of monitoring
points
875 79 22
Night-background
value
70130 28070 4232 550 29 2
Average
/background value
2.8 4.1 4.8 1.6 2.7 10.8
Table 2 Hospital indoor air particle diameter count value (particles/2.83L,
Segmented particle
size
0.3-
0.5μm
0.5-
1μm
1-3μm 3-5μm
5-
10μm
≥10μm
Average value
of monitoring points
79421 94110 19525 796 57 36
Night-background
value
23838 3682 521 27 20
Average/
background value
1.9 3.9 5.3 1.5 2.1 1.8
Table 3 Numerical value of segmented particle size of indoor air particles in hospitals
(particles/2.83L, min)
The hospital’s ward building has 12 floors above ground and 2 floors
underground. Floors 1-12 are inpatient departments, of which floors 3 and 9 are special
care units; floors 1 and 2 are diagnosis and treatment departments, and 2 floors
underground are radiotherapy machine rooms. The fan coil unit and fresh air are used,
the minimum fresh air volume is 30m3/(person·h), the ventilation method is natural
ventilation, and the average daily reception volume of the hospital is 1,500.
The subjective survey uses questionnaire surveys, and the survey population is
divided into outpatients, inpatients, and medical staff. A total of 500 copies of the
questionnaire survey indicators are shown in Table 1. The survey indicators are
selected by the surveyed personnel and divided into satisfaction and dissatisfaction.
Random questionnaires were selected during the peak period of visits from 09:00-11:00
and the general period from 14:00-17:00. The survey site was divided into outpatient
department and inpatient department. A total of 490 questionnaires were collected and
485 valid questionnaires were collected. The objective investigation was conducted in
accordance with the methods specified in the relevant management regulations [2-4]
issued by the Ministry of Health. Extract the centralized air conditioning and
ventilation systems of 5 general departments, and each system will extract 1 to 2
cooling towers and condensing parts, and select 1 to 5 representative parts for each
inlet pipe, air outlet and main air duct of the fresh air for sampling Detection. Each
sampling point is tested twice during the day and night, at 10:00 during the day and
22:00 at night.
2.2 Survey results and analysis
Table 1 Results of a subjective questionnaire survey of
indoor air quality in a hospital
It can be seen from Table 1 that, on the whole, people are dissatisfied with
the air quality in the hospital. Among the 8 items in the survey, there are 3 items
with a dissatisfaction rate of more than 50%; among them, except for noise, the
other 7 items They are directly related to indoor ventilation, especially the
dissatisfaction rate of indoor disinfection water and peculiar smell is 55.56% and
62.96%; 45.68% feel chest tightness, 41.98% have uncomfortable reaction, feel
tired and headache, the air quality in the hospital is worrying .
From a subjective point of view, the factors affecting hospital indoor air
quality are as follows:
(1) Volatilized odors such as disinfectants permeate the air. Disinfectant is
one of the commonly used medicines in hospitals. Due to its high volatility, if
the indoor volatile gas is not discharged in time, the indoor odor concentration
will rise sharply.
(2) The patient's personal hygiene is poor. The patients' own hygiene
concepts and qualities are uneven. The patients have poor personal hygiene due
to their own reasons, inconvenience, or health conditions. Some patients may
spit on the spot, and the clothes are not changed in time, and they do not take a
bath. The patient's bedpan is not cleaned in time, which causes poor indoor air
quality in the hospital.
(3) Since most of the nursing staff in my country have not been trained in professional
skills, nursing staff cannot provide patients with better health services and guidance
during the nursing process.
Dust is raised during floor cleaning and bed making, making the general ward
environment more unbearable, and even causing cross-infection between patients [5].
2.3 Objective investigation and analysis
In order to more intuitively reflect the air quality level of the hospital in the case of
high crowd density, and exclude the influence of other factors on the test results, the
background value is first taken before sampling the data of each monitoring point,
and the hospital has a relatively low night crowd density. The measurement result of
the indoor air particle diameter data is used as a benchmark to compare the air
quality level under high density. Table 2 and Table 3 show the results of air particle
diameter counting and segment counting.
It can be seen from the above table that the number of particles in each particle
size range in general departments far exceeds the background value measured at night
when the flow of people during the day is large, and the number of particles ≥0.3μm is
2.8 times the background value. The particle concentration in the 0.3 ~ 0.5μm particle
size range is 1.9 times the background concentration. The number of particles in the
other particle size ranges is also 3.9, 5.3, 1.5, 2.1 of the background value. , 1.8 times,
which shows that the dust concentration in general hospitals is generally higher and
the air quality is poor.
3 Hospital ventilation forms and
disadvantages
3.1 Disadvantages of ventilation design
Due to the imperfect design specifications of hospital
buildings, the conventional design usually treats general
departments as general comfort air conditioners. The original
"General Hospital Architectural Design Code" JGJ 49-88 has very
few provisions on HVAC, and the requirements are very broad. It
no longer meets the special requirements of modern hospitals. In
our country, ordinary comfort air conditioners are often seasonal
air conditioners. , Use temperature and humidity parameter
adjustment to achieve thermal comfort, adjust the cooling
(heating) amount of the system according to changes in indoor
sensible heat load,
Investigation and analysis of the status quo of ventilation in a general hospital
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The corresponding amount of dehumidification also keeps the indoor relative
humidity at an appropriate level. However, when the air conditioning unit is running
under partial load, the indoor sensible heat load decreases, and the cooling (heat)
supply decreases, which makes it difficult to meet the dehumidification
requirements, resulting in high indoor relative humidity, which provides a breeding
ground for indoor bacteria and viruses to breed and multiply [6].
3.2 Drawbacks of Operation Management
According to foreign experience, the energy consumption of hospital buildings
is generally 1.6 to 2.0 times that of office buildings. Since hospitals are large energy
consumers, there are often requirements for ensuring ventilation in clean areas such
as operating rooms and intensive care rooms. No fresh air or only part of the fresh air
is turned on to reduce the energy consumption of the hospital. In the wards and
outpatient clinics of large general hospitals, there are often a large number of patients
with weak resistance. It is possible for patients with infectious diseases to go to various
departments. Therefore, there are hidden dangers of cross-infection in each
department. The restriction of fresh air volume has aggravated the pollution of the air
environment, causing the concentration of bacteria and other microorganisms to
exceed the standard. This kind of operation mode of "switching on and limiting
electricity" sacrifices the original healthy environment, and the air cannot be updated,
increasing the risk of nosocomial infection and cross-contamination, which patients
often have to accept passively.
4 A new system for hospital ventilation
In the early days, most hospitals in our country adopted the fan-coil mode.
With the advancement of technology, the development of the hospital air-
conditioning system is constantly making new attempts to achieve a certain balance
between improving indoor ventilation effects and energy saving. Mainly include: full
air constant air volume air conditioning system CAV, variable air volume air
conditioning system VAV, multi-line VRV+ fresh air system. The above new air
conditioning and ventilation technologies have been partially adopted in major
hospitals in my country in recent years. The following is a brief summary of the
characteristics of various new systems Introduction.
(1) Variable air volume system: When the load is less than the peak load, it can
save the energy consumption of the fan by changing the processed air flow. If the
peak load of each air-conditioning area does not occur at the same time, this system
can sometimes reduce the size of the fan compared with the full-air constant air
volume system, which can achieve energy saving, flexibility, comfort, etc., but the
initial investment is higher. This form will destroy the hospital step pressure
Therefore, some regulations prohibit the use of variable air volume systems for air
conditioning in rooms with positive pressure control requirements.
(2) Full-air constant air volume system: It has relatively low control
complexity, and its initial investment and annual maintenance costs are relatively
low, and its life cycle cost is equivalent to that of a variable air volume system. It can
provide stable air flow organization. Compared with the variable air volume system,
because the energy input of the fan cannot be reduced during the low load period, it
usually requires a higher operating cost.
(3) Multi-online VRV system: It has been developed for many years and the
technology is mature. It is a high-efficiency refrigerant air-conditioning system that
timely meets the indoor cooling and heating load requirements by controlling the
refrigerant circulation of the compressor and the refrigerant flow into the indoor
heat exchanger. Its working principle is: the control system collects the indoor
comfort criteria, adjusts the compressor air volume by means of frequency
conversion or digital scroll, and controls all controllable components such as the fan
and electronic expansion valve of the air conditioning system to ensure the comfort
of the indoor environment Performance, make the system work stably in the best
condition. The most obvious advantage lies in the ease of design, construction and
operation. Of course, there are also some problems, such as pipe length restrictions,
outdoor unit layout and other issues. In recent years, the development trend has been
relatively fast, and VRV is even considered to be the development trend of ward air
conditioning.
(4) Fan coil + fresh air system: It is a semi-centralized air conditioning
processing equipment, which is the most widely used in hospital air conditioning in my
country, and it also exposes some problems to be solved. Due to the low price of fan-
coil units in my country and too many crude products, the wet-coil units are prone to
bacteria and cause secondary pollution. Some hospitals even consider fan-coil air
conditioners to be a symbol of backwardness.
(5) Return air circulation: The pathogenic microorganisms enter the air through
the return air outlet through the particle carrier, and are sent to the air conditioning
unit through the return air duct to be mixed with other fresh and return air (mainly
cooling or heating), and then sent back to each The indoor environment causes the
movement, spread, and diffusion of bacteria-carrying particles from the contaminated
area to the clean area, which can easily cause infection in the hospital for susceptible
people. In fact, this type of ventilation system has become an important route for
airborne nosocomial infections (not just respiratory infectious diseases).
(6) Non-exhaust system: only use the gaps between doors and windows to
exhaust air, which may cause excessive indoor pressure and the fresh air cannot be sent
into the room; in addition, unorganized exhaust air poses a safety hazard and increases
the risk of cross-infection in various sick rooms.
5 Conclusion
A subjective investigation and analysis of the air quality in a
hospital showed that the indoor air quality in the hospital was poor,
especially reflected in the subjective perception of the human body.
The dissatisfaction rate of indoor disinfection water and peculiar smell
exceeded 50%; the objective survey results showed that the hospital
indoor dust concentration On the high side. The above phenomenon is
universal in domestic hospitals. This is closely related to the
inappropriate ventilation form of domestic hospitals at this stage. For
example, the design of hospital ventilation system is not highly
standardized, and the design procedure does not consider the
particularity of the hospital as a type of public building. This leads to
poor indoor air quality in hospitals, poor ventilation safety, and high
cross-infection probability; indoor air environment protection facilities
are simple and backward, and energy consumption is high. Therefore,
to further improve the indoor ventilation effect of hospitals in our
country, not only depends on the ventilation system and technological
innovation, but also requires government departments to further
regulate the hospital ventilation design regulations, and fully consider
their particularities to improve the comfort of the hospital indoor air.
And safety, to create a good medical environment for the majority of
patients.
Investigation and analysis of the status quo of ventilation in a general hospital
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