www.sensirion.com Version 2.0 – November 2019 – D1 1/5
Total Volatile Organic Compounds (TVOC) and Indoor Air Quality (IAQ)
SGP30 TVOC and CO2eq Sensor
1 Introduction
The following document explains in Section 2 the term of
total volatile organic compounds (TVOC) and why this
quantity is related to indoor air quality (IAQ) and the so-
called IAQ levels. Since Sensirion’s SGP30 gas sensor is
responsive to a broad range of volatile organic compounds
(VOC) and other gases relevant for indoor air quality, the
present gas sensing technology is well-suited for monitoring
TVOC concentrations and for translating those into IAQ
levels. In order to meet Sensirion’s high quality standards,
each SGP30 sensor is calibrated upon production.
Figure 1 Added value chain of Sensirion's SGP30 gas sensor
schematically shows the different verification steps from real-life
indoor air quality application to verification in production.
Ref.: Indoor air – test methods for VOC detectors, ISO16000-
29:2104(E).
VOC = Volatile Organic Compounds includes all chemicals
based on carbon chains or carbon rings with a vapor pressure
larger than 0.01 kPa at room temperature, i.e., at 293 K or 20 °C.”
Ref.: Council Directive 1999/13/EC of 11 March 1999 on the
limitation of emissions of volatile organic compounds due to the
use of organic solvents in certain activities and installations.
TVOC = Total Volatile Organic Compounds includes the sum
of all VOCs which elute between and including n-hexane and n-
hexadecane on a non-polar capillary column.
Section 3 lists possible sources of VOCs and gives an
overview of applications based on monitoring TVOC such
as controlled air purification and ventilation enabled by
SGP30 sensors.
Section 4 explains why Sensirion uses ethanol as target
gas for calibration and why it serves as a reliable, accurate,
harmless, and inexpensive proxy for TVOC by comparison
with the ISO norm for indoor air quality.
2 TVOC and Indoor Air Quality
2.1 Definition of TVOC and Relation to Indoor Air
Quality
The sum of VOCs
and is used as
an indication for VOC contamintation. VOC contamination
is an established concept in regulatory and scientific
literature. Note that the specfic TVOC composition varies
between different ambient indoor environments and indoor
air is always composed of different volatile organic
substances.
Therefore, it is helpful to consider TVOC
concentrations as statistical reference values which help to
Ref. (a): DIN ISO 16000-6: Innenraumluftverunreinigungen (ISO
16000-6:2014), Beuth Verlag, Berlin.
Ref. (b): ECA (1997) (European Collaborative Action „Indoor Air
Quality and its Impact on Man“): Total Volatile Organic
Compounds (TVOC) in Indoor Air Quality Investigations. Report
No. 19.
Ref. (c): Mølhave L, Bach R, Pederson OF, Environ Int 12:167–
175 (1986).
Ref.: Mølhave L, Clausen G, Berglund B, et al. (1997) Total
Volatile Organic Compounds (TVOC) in Indoor Air Quality
Investigations. Indoor Air 7:225–240.
Preface
The SGP30 is a MOX based multi-pixel gas sensor capable
of detecting small ambient concentrations of TVOC. The
following document describes what TVOC is, lists possible
sources, and explains how TVOC concentrations are
related to indoor air quality. In real-life applications TVOC
denotes a mixture of various abundant volatile organic
compounds.
Therefore it is helpful to test TVOC sensor performance
under laboratory conditions with so called TVOC proxies,
e.g., defined by the ISO16000-29 norm for indoor air
quality. This document explains what those ISO normed
test gases are and shows that Sensirion’s SGP30 gas
sensor reveals similar performance for both the ISO-
normed TVOC test gas and ethanol, respectively. This
reasoning explains why ethanol is used for calibration and
specification of the SGP30 TVOC sensor.
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