Necessity Of Ventilation - Mitsubishi Electric Lossnay series Technical Manual

•
CHAPTER 1 Ventilation for Healthy Living
Ventilation air must be introduced constantly at a set ratio in an air-conditioning system. The ventilation air introduced is to be
mixed with the return air to adjust the temperature and humidity, supply oxygen, reduce odors, remove tobacco smoke, and to
increase the air cleanliness.
The standard ventilation (outdoor air intake) volume is determined according to the type of application, estimated number of
occupants in the room, room area, and relevant regulations. Systems that accurately facilitate these requirements are required
in buildings.

1. Necessity of Ventilation

The purpose of ventilation is basically divided into "oxygen supply" , "air cleanliness" , "temperature control" and "humidity control" .
Air cleanliness includes eliminating "odors" , "gases" , "dust" and "bacteria" . Ventilation needs are divided into "personal comfort" ,
"optimum environment for animals and plants" , and "optimum environment for machinery and constructed materials" .
Ventilation regulations are detailed in a variety of codes and standards applied to mechanical systems in buildings. Energy
efficiency codes also often apply to the design of ventilation systems.
1.1 Room Air Environment in Buildings
In Japan, the "Building Management Law" , a law concerning the sanitary environment in buildings, designates 11 applications
including offices, shops, and schools with a total floor area of 32,300ft
and ventilation, water supply, discharge management according to the Environmental Sanitation Management Standards is
obligatory.
The following table gives a specific account of buildings in Tokyo.
(Tokyo Food and Environment Guidance Center Report)
Specific Account of Buildings in Tokyo (March, 2003)
Offices
Shops
Department Stores
Schools
Inns
Theaters
Libraries
Museums
Assembly Halls
Art Museums
Amusement Centers
Total
Note: Excludes buildings with an expanded floor space of 32,300 to 58,820ft
Results of the air quality measurement public
inspection and the standard values that were
not met (percentage of unsuitability) for the
approximately 500 buildings examined in 1980
are shown in the chart at the right.
There was a large decrease in high percentages
of floating particles, but there was almost no
change in temperature and carbon dioxide. The
highest percentage of unsuitability in 2006 is
relative humidity with 36%, followed by carbon
dioxide at 28%.
U-2
2 2
(3,000m ) or more, as buildings. Law maintenance
Number of Buildings
1,467
309
63
418
123
86
12
11
63
8
27
2,587
2
(3,000 to 5,000m
Percentage Unsuitable Air Quality by Year
60
relative humidity
carbon dioxide
50
40
30
20
10
0
71 7375 76 77 78 79 80 81 82 83 84 85 86 87 8889 90 91 92 93 94 95 96 97 98 9900 01 02 03 0405 06
(From reference data in the 2006 edition of the "Water Supply
Division, Dept. of Localized Public Health, Tokyo Metropolitan
Government, Bureau of Public Health")
%
56.7
22.0
2.4
16.2
4.8
3.3
0.5
0.4
2.4
0.3
1.0
100.0
2
) in particular areas.
temperature ventilation
carbon monoxide floating particles
(tobacco smoke)
(year)