ASHRAE Journal - June 2019 - 75

COLUMN IEQ APPLICATIONS

another:7 working memory, inhibition and task switching. Working memory refers to our ability to hold information in mind and manipulate it. Inhibition refers to
our ability to control attention, behavior, thinking and
emotions to override habits or impulses. Task switching
refers to our ability to ﬂexibly switch between tasks with
different demands. An example of a working memory
test is the operation span (OSPAN),8 in which people
solve math problems under time pressure while simultaneously remembering an increasing list of letters or
words for later recall.
An example of an inhibition test is the Stroop test,9 in
which people respond to what color words (i.e., names
of colors) appear in as quickly as possible. Sometimes
the words and names are congruent (RED written in
red), and sometimes incongruent (BLUE written in red),
requiring inhibition of automatic responses.
An example of a task switching test is the magnitude/
parity task,10 in which people switch between identifying whether digits are greater vs. less than ﬁve and
whether digits are even vs. odd.
Tests of all three executive functions should be given at
the same time, because environmental conditions may
affect one type of executive function, while not affecting
others, a phenomenon we have seen in our Well Living
Lab research. This is important to understand, as it will
lead to effectively designing environments for speciﬁc
tasks. For example, working memory is very important
for brainstorming,11 while work that involves multitasking or regaining focus after interruption (e.g., in emergency departments12) requires task switching. We cannot
design effective environments without understanding
how conditions impact relevant cognitive functions.
Measures of executive functions can be supplemented
with speciﬁc measures of cognitive functions relevant to
intended tasks. For example, spatial cognition, including the abilities to visualize and mentally manipulate
objects and to understand spatial relationships, is very
important for success in physical science, math, computer science and engineering.13 If the goal of a project
is to understand how an ofﬁce environment impacts the
cognitive performance of engineers, adding a task measuring spatial cognition would be appropriate.
We suggest a few best practices for cognitive performance measures: Use valid tests grounded in current
knowledge from cognitive and behavioral sciences.
Understand what cognitive function the test you are

using measures, and how it works. And ﬁnally, combine
tests measuring different cognitive functions to get a
complete picture of how an environment impacts cognitive performance.

How Does the Indoor Environment Impact Performance?
The indoor environment can support people's cognitive performance, task performance and productivity, or
actively erode it.
In general, performance can be linked to comfort:
people tend to perform better when physically comfortable. An environment that is actively uncomfortable can
be distracting, drawing attention away from the task at
hand, and requiring effort to ignore. For example, in a
study of combinations of environmental conditions in
a living lab ofﬁce, we found that uncomfortable environmental conditions increased distraction and effort,
affecting people's self-reported ability to work.14
Providing a comfortable thermal, lighting, and
acoustic environment with good air quality can support people's performance.5 For example, a too-cold
or too-hot thermal environment can be disruptive to
performance.15 Access to daylight and views can support
people's performance,4 and access to views of natural
elements can provide a link to nature, which may help
restore people's attention and improve performance.16
There is no one-size-ﬁts-all environment for performance, so it is essential to consider occupants'
intended tasks. For example, auditory distraction from
overheard speech is particularly disruptive to focused
work,17 so areas designed for individual focused work
need to block noise from collaborative areas and
reduce the intelligibility of speech. Recent work suggests that providing occupants with a choice of different environments may allow them to choose the most
appropriate environment for the task and for their
personal preferences.18
Future research will undoubtedly uncover further
links between environmental conditions and performance. For now, two general strategies to improve
occupants' performance are to prioritize comfort and to
provide a choice of environmental conditions for different tasks.

References

1. Barrett, P., F. Davies, Y. Zhang, and L. Barrett. 2015. "The
impact of classroom design on pupils' learning: Final results of a
holistic, multi-level analysis." Build. Environ. 89:118 - 133.
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ASHRAE Journal - June 2019

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