ASHRAE Journal - February 2011 - 36

Thus, a 4 cu ft quantity is the minimum ventilation requirement for closed spaces according to Tredgold and his contemporaries of 1836. Another work which was published a few years after the above reference also presents some interesting points when examining the rationale behind the minimum requirements for ventilation. This work was entitled The History and Art of Warming and Ventilating by Meikleham,2 which appeared in 1845 and, therefore, espoused the carbon dioxide contamination theory of Lavoisier. This author proceeded as follows. Inhaled air contains about 20% oxygen and the exhaled air only 11 to 12%. These values differ significantly from the information which we have today relating to the quantities of oxygen taken up in the bloodstream. Only about one-fifth of inhaled oxygen is sent through the bloodstream. Nevertheless, let us proceed with Meikleham’s reasoning. If the maximum amount of carbon dioxide gas permissible is 3.5%, then 8 to 9% exceeds the permissible amount by approximately 2.4 times. The average person breathes in about 600 cu in. per min and, therefore, renders unfit for breathing 2.4 times this amount, or 1440 cu in. each min. In addition to this, he takes into account that the human body gives off about 23 grains of water per min. Each cu ft of air at 64°F with 50% rh could carry off at most 2.48 grains of water. Therefore it would require 9.25 cfm of air to remove the body moisture. The sum of 9.25 cu ft for moisture dissipation and approximately 1 cu ft (1440

Figure 1: Typical minimum outdoor air requirement. igure T
Leveling Off of Requirement 30 Steadily Rising Requirement cfm 20 Revaluation Requirement 10 Accepted Requirement Subject to Revaluation Flugge’s Breakthrough (1905)

1800

1850

1900

1950

www.info.hotims.com/33861-32

cu in.) for carbon dioxide dissipation totals 10.25 cu ft which would then be the minimum ventilation requirement per min. It was not until 1862 that Max Von Pettenkofer,3 in Germany, first expressed the theory that carbon dioxide was no more responsible for making air unfit to breathe than was the depletion of the oxygen content. He stated that under normal conditions the carbon dioxide concentration will never reach levels where it will have any harmful physiological effects. Subsequent experience has shown that in well-constructed dwellings, oxygen content may fall from 21 to 20% and carbon dioxide may rise from 0.03 to 0.5%. Greater changes than these are not observed even in the most crowded and poorly ventilated rooms. Practical limits on construction techniques preclude elimination of all leaks to outdoor air; therefore, only a hermetically sealed structure can be said to be leak-free and, consequently, totally ventilation-free. A ventilationfree structure would be the only type of enclosure in which oxygen depletion and carbon dioxide build-up would be cause for concern. A decrease in oxygen concentration of 1 or 2% has no harmful physiological effects as witnessed by the fact that the body has no problem adapting to reduced oxygen partial pressures encountered at the higher elevations. In fact, many health resorts (e.g., the Tuberculosis Sanatorium at Tupper Lake, N.Y.) are located at higher elevations and are known to provide extremely healthful climates. Limited carbon dioxide content increases (up to 0.5%) have also been shown to produce no harmful effects. Only at carbon dioxide concentrations higher than those levels which could normally be expected to
	 	 February	 2011

36	

ASHRAE	Journal	



ASHRAE Journal - February 2011

Table of Contents for the Digital Edition of ASHRAE Journal - February 2011

ASHRAE Journal - February 2011
Contents
Commentary
Industry News
Letters
Meetings and Shows
Feature Articles
Thermal Coupling of Cooling and Heating Systems
10 Common Problems in Energy Audits
Hall of Fame Feature: History of the Changing Concepts in Ventilation Requirements
A Guide to Wireless Technologies
Building Sciences
Solar NZEB Project
Emerging Technologies
People
Special Section
InfoCenter
Commissioning
Products
Washington Report
Classified Advertising
Advertisers Index
ASHRAE Journal - February 2011 - ASHRAE Journal - February 2011
ASHRAE Journal - February 2011 - Cover2
ASHRAE Journal - February 2011 - 1
ASHRAE Journal - February 2011 - 2
ASHRAE Journal - February 2011 - Contents
ASHRAE Journal - February 2011 - Commentary
ASHRAE Journal - February 2011 - 5
ASHRAE Journal - February 2011 - Industry News
ASHRAE Journal - February 2011 - 7
ASHRAE Journal - February 2011 - Letters
ASHRAE Journal - February 2011 - 9
ASHRAE Journal - February 2011 - 10
ASHRAE Journal - February 2011 - 11
ASHRAE Journal - February 2011 - 12
ASHRAE Journal - February 2011 - 13
ASHRAE Journal - February 2011 - 14
ASHRAE Journal - February 2011 - 15
ASHRAE Journal - February 2011 - Meetings and Shows
ASHRAE Journal - February 2011 - 17
ASHRAE Journal - February 2011 - Thermal Coupling of Cooling and Heating Systems
ASHRAE Journal - February 2011 - 19
ASHRAE Journal - February 2011 - 20
ASHRAE Journal - February 2011 - 21
ASHRAE Journal - February 2011 - 22
ASHRAE Journal - February 2011 - 23
ASHRAE Journal - February 2011 - 24
ASHRAE Journal - February 2011 - 25
ASHRAE Journal - February 2011 - 10 Common Problems in Energy Audits
ASHRAE Journal - February 2011 - 27
ASHRAE Journal - February 2011 - 28
ASHRAE Journal - February 2011 - 29
ASHRAE Journal - February 2011 - 30
ASHRAE Journal - February 2011 - 31
ASHRAE Journal - February 2011 - 32
ASHRAE Journal - February 2011 - 33
ASHRAE Journal - February 2011 - Hall of Fame Feature: History of the Changing Concepts in Ventilation Requirements
ASHRAE Journal - February 2011 - 35
ASHRAE Journal - February 2011 - 36
ASHRAE Journal - February 2011 - 37
ASHRAE Journal - February 2011 - 38
ASHRAE Journal - February 2011 - 39
ASHRAE Journal - February 2011 - 40
ASHRAE Journal - February 2011 - 41
ASHRAE Journal - February 2011 - 42
ASHRAE Journal - February 2011 - 43
ASHRAE Journal - February 2011 - A Guide to Wireless Technologies
ASHRAE Journal - February 2011 - 45
ASHRAE Journal - February 2011 - 46
ASHRAE Journal - February 2011 - 47
ASHRAE Journal - February 2011 - 48
ASHRAE Journal - February 2011 - 49
ASHRAE Journal - February 2011 - Building Sciences
ASHRAE Journal - February 2011 - 51
ASHRAE Journal - February 2011 - 52
ASHRAE Journal - February 2011 - 53
ASHRAE Journal - February 2011 - 54
ASHRAE Journal - February 2011 - 55
ASHRAE Journal - February 2011 - 56
ASHRAE Journal - February 2011 - 57
ASHRAE Journal - February 2011 - 58
ASHRAE Journal - February 2011 - 59
ASHRAE Journal - February 2011 - 60
ASHRAE Journal - February 2011 - 61
ASHRAE Journal - February 2011 - Solar NZEB Project
ASHRAE Journal - February 2011 - 63
ASHRAE Journal - February 2011 - 64
ASHRAE Journal - February 2011 - 65
ASHRAE Journal - February 2011 - 66
ASHRAE Journal - February 2011 - 67
ASHRAE Journal - February 2011 - 68
ASHRAE Journal - February 2011 - 69
ASHRAE Journal - February 2011 - Emerging Technologies
ASHRAE Journal - February 2011 - 71
ASHRAE Journal - February 2011 - 72
ASHRAE Journal - February 2011 - 73
ASHRAE Journal - February 2011 - 74
ASHRAE Journal - February 2011 - 75
ASHRAE Journal - February 2011 - People
ASHRAE Journal - February 2011 - 77
ASHRAE Journal - February 2011 - InfoCenter
ASHRAE Journal - February 2011 - 79
ASHRAE Journal - February 2011 - 80
ASHRAE Journal - February 2011 - 81
ASHRAE Journal - February 2011 - 82
ASHRAE Journal - February 2011 - 83
ASHRAE Journal - February 2011 - 84
ASHRAE Journal - February 2011 - 85
ASHRAE Journal - February 2011 - Commissioning
ASHRAE Journal - February 2011 - 87
ASHRAE Journal - February 2011 - 88
ASHRAE Journal - February 2011 - 89
ASHRAE Journal - February 2011 - 90
ASHRAE Journal - February 2011 - Products
ASHRAE Journal - February 2011 - Washington Report
ASHRAE Journal - February 2011 - Classified Advertising
ASHRAE Journal - February 2011 - 94
ASHRAE Journal - February 2011 - 95
ASHRAE Journal - February 2011 - Advertisers Index
ASHRAE Journal - February 2011 - Cover3
ASHRAE Journal - February 2011 - Cover4
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