Några inomhusväxters förmåga att påverka luftkvaliteten
Doctoral thesis, 2004
People spend more than 80 % of the day indoors and are mostly exposed to contaminated air. Some
authors suggest that indoor plants are good as indoor air cleaners. Authors have studied the sink
effect of indoor plants in unventilated closed systems. Unfortunately, the results from these studies
cannot be applied in the design of HVAC-systems because they do not contain proper parameters,
such as air change rate.
In this study the sink and source effects of three different indoor plants have been investigated for
carbon dioxide (CO2), formaldehyde (FAD), and total volatile organic compound (TVOC). The
measurements have been made in two different climate chambers, a climate box of 0.56 m3 and a
clean room of 19.6 m3. Both inlet and outlet air concentrations of CO2, FAD, TVOC, and content of
water were measured. In addition the light intensity levels, lux and photoactive radiation (Par), were
measured. The three following families of indoor plants have been tested: Epipremnum, Schefflera
A new method of measuring leaf area is described. The plants leaf area has been measured with a
photo scanner for a selected number of leaves and the relationship between the characteristic length
and the area has been calculated using regression analysis. The characteristic length was measured
for all leaves of the plants and used to calculate the total leaf area.
A special mixture, containing six ordinary volatile organic compounds normally found in indoor air,
was used to simulate TVOC. The concentration of TVOC was measured using photo acoustic
infrared spectroscopy (PAS).
Both single step and double step forward finite difference methods have been used for the
calculations of the indoor concentration dilution of contaminants. The latter method is preferred
when using one single instrument and a switching valve for monitoring the concentration and gas
flow from both the inlet and the outlet of the chamber. In the calculations the influence of the
chamber has been taken into consideration.
The results show that for the studied plants, the sink effect of CO2 is -0.05 to -0.1 g CO2 m-2 h-1 at
day-time (500 lx) and that the source strength at night-time is 0.1 g CO2 m-2 h-1 when the inlet
concentration of CO2 air is 400 ppm. If the inlet air concentration is 1500 ppm CO2 the sink effect is
larger, ranging from -2 to -6 g CO2 m-2 h-1. The sink effect of FAD is in the range of -0.3 to -1
mg FAD m-2 h-1 (at the background concentration of 0.3 mg FAD m-3), and the sink effect of
TVOCpas is -0.25 to - 0.5 mg TVOCpas m-2 h-1 (at the background concentration of 1-2
mg TVOCpas m-3). The source strength of water is in the range of 0.005-0.01 g H2O m-2 h-1 (at nighttime)
and 0.008 to 0.01 g H2O m-2 h-1 (at day-time).
The thesis is written in Swedish.
13.15 VF-salen, Sven Hultins gata 6, Chalmers
Opponent: Fil dr Lars Gunnarsen, SBI, Hörsholm, Danmark