ASHRAE Journal - April 2021 - 60

COLUMN IEQ APPLICATIONS

different effects on sleep quality were seen, while above
2,585 ppm, negative effects on next-day performance
have also been demonstrated. On the basis of these
findings, a simple recommendation would be to keep
bedroom CO2 below 800 ppm and avoid higher levels
because they are likely to disturb sleep up to 2,600 ppm
and to decrease next-day performance above 2,600
ppm.
These recommendations require validation and
verification, which are planned in ASHRAE Research
Project 1837 on ventilation and sleep quality in different climatic zones. At present, our recommendations
use CO2 as a marker of the outdoor air ventilation
rate to the bedroom. The caveat for this approach is
that CO2 may not sufficiently account for other pollutants present indoors, including those brought
from outdoors; yet, human bioeffluents are likely to
be the major source of pollution in bedrooms, and
under these conditions CO2 is a fairly good marker of
ventilation sufficiency. Nevertheless, in the future,
the effects of different sources of air pollution in bedrooms on sleep should be investigated,13,14 as well as
interactions with thermal and acoustic conditions in
bedrooms.

Future Outlook

The limited number of studies published to date
show consistently that poor bedroom ventilation has
negative consequences for sleep quality and nextday performance. Considering that poor bedroom
ventilation has been reported in both temperate and
tropical climates,15 and taking into account the sparse
standards and guidelines for the ventilation of bedrooms,3 it would be prudent to intensify research in
this area, extending it to studies of thermal effects
on sleep quality16 and their interaction with IAQ and
other parameters. In many bedrooms, ventilation is
achieved by window and door opening and infiltration. This can increase external noise, moisture and
insect penetration and result in bedroom temperatures that are too low in cold climates or too high in
hot climates.
Additionally, research is required to develop bedroom
ventilation solutions for newly constructed buildings
and retrofit solutions for existing buildings that will
ensure that bedroom IAQ does not disturb sleep and is of
sufficient quality to minimize health and other risks.
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Acknowledgment

This column was prepared as part of ASHRAE Research
Project 1837, " The Effects of Ventilation in Sleeping
Environments. " Additional support was received
from the China Scholarship Council and Research
Foundation-Flanders.

References

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ASHRAE Journal - April 2021

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