ASHRAE Journal - September 2019 - 72

COLUMN PRODUCTIVITY-ASHRAE

these experiments. Five studies12,13,16,17,20 found SS
decreases in aspects of cognitive performance, when
CO2 concentrations were increased and, in some
instances, the performance decreases were quite substantial in magnitude. Concentrations of CO2 as low as
approximately 1,000 ppm, relative to 500 to 600 ppm,
significantly reduced performance.13,17 Four of these
five studies13,16,17,20 employed demanding tests of cognitive performance, either a 90-minute assessment of
decision making via a test system called the strategic
management simulation (SMS) or a 180-minute test of
pilots' performance in flight simulations. One of these
studies20 found an SS reduction in decision-making
performance at 1,200 ppm CO2 relative to 600 ppm, but
performance decreases were not found at 2,500 or 5,000
ppm CO2. Besides assessing performance in decisionmaking, this study also employed a battery of more
traditional cognitive performance tests and performance in this battery of tests was generally not affected
by CO2 concentrations. The exception was a general
trend toward reduced performance with 1,200 ppm CO2

with the reduction in speed at 1,200 ppm being SS. The
fourth study12 found a SS decrease in performance of
a proof reading task but not in other tasks, when CO2
levels were increased to 3,000 ppm, and proof-reading
performance decreased only in one of two experiments.
Five additional studies14,18,19,22,23 found that CO2 levels
had no SS effects on performance. Four of these studies14,19,22,23 used tests of task performance (e.g., arithmetic tasks, text typing, proof reading, memory) as well
as tests of reaction time and attention. In one study,23
CO2 levels as high as 5,000 ppm did not influence performance. One of these studies,19 was conducted at high
indoor air temperature of 95°F (35°C) and increased
CO2 did not modify responses attributable to increased
temperature. The fourth study18 found CO2 levels as
high as 15,000 ppm to not affect performance in the SMS
test. Overall, among the 10 studies, three13,16,17 provide
strong evidence of reductions in cognitive performance
with increased levels of CO2. Two additional studies12,20
provide limited evidence of cognitive performance
decreases with increased CO2 levels, but also include

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ASHRAE Journal - September 2019

Table of Contents for the Digital Edition of ASHRAE Journal - September 2019

Contents
ASHRAE Journal - September 2019 - Intro
ASHRAE Journal - September 2019 - Cover1
ASHRAE Journal - September 2019 - Cover2
ASHRAE Journal - September 2019 - 1
ASHRAE Journal - September 2019 - Contents
ASHRAE Journal - September 2019 - 3
ASHRAE Journal - September 2019 - 4
ASHRAE Journal - September 2019 - 5
ASHRAE Journal - September 2019 - 6
ASHRAE Journal - September 2019 - 7
ASHRAE Journal - September 2019 - 8
ASHRAE Journal - September 2019 - 9
ASHRAE Journal - September 2019 - 10
ASHRAE Journal - September 2019 - 11
ASHRAE Journal - September 2019 - 12
ASHRAE Journal - September 2019 - 13
ASHRAE Journal - September 2019 - 14
ASHRAE Journal - September 2019 - 15
ASHRAE Journal - September 2019 - 16
ASHRAE Journal - September 2019 - 17
ASHRAE Journal - September 2019 - 18
ASHRAE Journal - September 2019 - 19
ASHRAE Journal - September 2019 - 20
ASHRAE Journal - September 2019 - 21
ASHRAE Journal - September 2019 - 22
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ASHRAE Journal - September 2019 - 24
ASHRAE Journal - September 2019 - 25
ASHRAE Journal - September 2019 - 26
ASHRAE Journal - September 2019 - 27
ASHRAE Journal - September 2019 - 28
ASHRAE Journal - September 2019 - 29
ASHRAE Journal - September 2019 - 30
ASHRAE Journal - September 2019 - 31
ASHRAE Journal - September 2019 - 32
ASHRAE Journal - September 2019 - 33
ASHRAE Journal - September 2019 - 34
ASHRAE Journal - September 2019 - 35
ASHRAE Journal - September 2019 - 36
ASHRAE Journal - September 2019 - 37
ASHRAE Journal - September 2019 - 38
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ASHRAE Journal - September 2019 - 49
ASHRAE Journal - September 2019 - 50
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ASHRAE Journal - September 2019 - 53
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ASHRAE Journal - September 2019 - 55
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ASHRAE Journal - September 2019 - 60
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ASHRAE Journal - September 2019 - 70
ASHRAE Journal - September 2019 - 71
ASHRAE Journal - September 2019 - 72
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ASHRAE Journal - September 2019 - Cover3
ASHRAE Journal - September 2019 - Cover4
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