Green wall technology for the phytoremediation of indoor air: a system for the reduction of high CO2 concentrations

Abstract

Along with the growing requirement to reduce building carbon emissions, a need has arisen to find energy efficient means of improving the quality of indoor air. Indoor plants have been shown to be capable of reducing most air pollutants; however, practical numbers of potted plants will not have the capacity to control many forms of air pollution, especially CO2. Green walls are space-efficient means of increasing the density of indoor plants. We assessed an active green wall for its potential to reduce CO2 in chambers and a test room. Chlorophytum comosum and Epipremnum aureum were both effective cultivars for CO2 removal at light densities greater than 50 μmol m⁻² s⁻¹. Substrate ventilation increased the rate of CO2 draw down from chambers, possibly due to increased leaf gas exchange rates. Green walls were then tested in a 15.65-m³ sealed simulation room, allowing the calculation of clean air delivery rate (CADR) and air changes per hour (ACH) equivalents based on CO2 draw down. Rates of CO2 draw down were modest under typical brightly lit indoor conditions (50 μmol m⁻² s⁻¹); however, when light intensity was increased to relatively bright levels, similar to indoor conditions next to a window or with the addition of supplementary lighting (250 μmol m⁻² s⁻¹), a 1-m² green wall was capable of significant quantifiable reductions of high CO2 concentrations within a sealed room environment. Extrapolating these findings indicates that a 5-m² green wall containing C. comosum could balance the respiratory emissions of a full-time occupant.

Full text

Green wall technology for the phytoremediation of indoor air:
a system for the reduction of high CO
2
concentrations
FR Torpy
1
&MZavattaro
2
&PJ Irga
1
Received: 17 August 2016 /Accepted: 14 November 2016 /Published online: 30 November 2016
#Springer Science+Business Media Dordrecht 2016
Abstract Along with the growing requirement to reduce
building carbon emissions, a need has arisen to find energy
efficient means of improving the quality of indoor air. Indoor
plants have been shown to be capable of reducing most air
pollutants; however, practical numbers of potted plants will
not have the capacity to control many forms of air pollution,
especially CO
2
. Green walls are space-efficient means of in-
creasing the density of indoor plants. We assessed an active
green wall for its potential to reduce CO
2
in chambers and a
test room. Chlorophytum comosum and Epipremnum aureum
were both effective cultivars for CO
2
removal at light densities
greater than 50 μmol m
−2
s
−1
. Substrate ventilation increased
the rate of CO
2
draw down from chambers, possibly due to
increased leaf gas exchange rates. Green walls were then
tested in a 15.65-m
3
sealed simulation room, allowing the
calculation of clean air delivery rate (CADR) and air changes
per hour (ACH) equivalents based on CO
2
draw down. Rates
of CO
2
draw down were modest under typical brightly lit
indoor conditions (50 μmol m
−2
s
−1
); however, when light
intensity was increased to relatively bright levels, similar to
indoor conditions next to a window or with the addition of
supplementary lighting (250 μmol m
−2
s
−1
), a 1-m
2
green wall
was capable of significant quantifiable reductions of high CO
2
concentrations within a sealed room environment.
Extrapolating these findings indicates that a 5-m
2
green wall
containing C.comosum could balance the respiratory emis-
sions of a full-time occupant.
Keywords Carbon dioxide .Indoor environment .
Biofiltration .Phytoremediation .Sustainable buildings .
Active green walls
Introduction
Urban air pollution is a worldwide health concern; health care
and associated costs for developed countries related to just the
indoor component of air pollution have been estimated at
nearly US$90 trillion Hutton (2013). Health problems associ-
ated with indoor air pollution may have led to as many as
81,000 mortalities per year in the Americas alone (WHO
2014). Indoor air quality has thus become a major internation-
al health issue and has been designated as a significant health
concern in both the USA and Europe for many years
(Bernstein et al. 2008; Morey et al. 2001; Ayala et al. 2012).
Indoor air pollution can be more concentrated than outdoors;
as outdoor-sourced contaminated air enters through natural or
mechanical ventilation, it mixes with indoor-sourced pollut-
ants, especially higher carbon dioxide (CO
2
) from human re-
spiratory emissions (Norbäck and Nordström 2008). Although
CO
2
is not toxic per se, at elevated concentrations (over
~1000 ppm by volume; ppmv), it has been associated with
adverse health effects through its narcotic action (Milton
et al. 2000; Erdmann and Apte 2004; Seppänen and Fisk
2004), mucous membrane and lower respiratory tract symp-
toms (Erdmann and Apte 2004), which lead to occupant
Electronic supplementary material The online version of this article
(doi:10.1007/s11869-016-0452-x) contains supplementary material,
which is available to authorized users.
*FR Torpy
Fraser.Torpy@uts.edu.au
1
Plants and Environmental Quality Research Group, School of Life
Sciences, Faculty of Science, University of Technology Sydney,
P.O. Box 123, Broadway, Ultimo, NSW 2007, Australia
2
School of Life Sciences, Faculty of Science, University of
Technology Sydney, P.O. Box 123, Broadway, Ultimo, NSW 2007,
Australia
Air Qual Atmos Health (2017) 10:575–585
DOI 10.1007/s11869-016-0452-x
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