U-2
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
2
(3,000m
2
) or more, as buildings. Law maintenance
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)
Specic Account of Buildings in Tokyo (March, 2003)
Note: Excludes buildings with an expanded oor space of 32,300 to 58,820ft
2
(3,000 to 5,000m
2
) in particular areas.
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%.
70
60
50
40
30
20
10
0
Percentage of unsuitable air quality (%)
Percentage of unsuitable air quality (%)
76 77 78 79 80 8171 72 73 74 75
82
83 84
85
86
87
88 89
90
91 92 93 94 95 96 97 98 99 00 01 02
76 77 78 79 80 8171 73 75
82
83 84
85
86
87
88 89
90
91 92 93 94 95 96 97 98 9900 01 02 03 0405 06
(year)
relative humidity
carbon dioxide
temperature
carbon monoxide
ventilation
floating particles
(tobacco smoke)
0
10
20
30
40
50
60
relative humidity
carbon dioxide
temperature
carbon monoxide
ventilation
floating particles
(tobacco smoke)
Percentage Unsuitable Air Quality by Year
(From reference data in the 2006 edition of the “Water Supply
Division, Dept. of Localized Public Health, Tokyo Metropolitan
Government, Bureau of Public Health”)
Number of Buildings %
Offices 1,467 56.7
Shops 309 22.0
Department Stores 63 2.4
Schools 418 16.2
Inns 123 4.8
Theaters 86 3.3
Libraries 12 0.5
Museums 11 0.4
Assembly Halls 63 2.4
Art Museums 8 0.3
Amusement Centers 27 1. 0
Total 2,587 100.0
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