Några inomhusväxters förmåga att påverka luftkvaliteten

Sammanfattning: People spend more than 80 % of the day indoors and are mostly exposed to contaminated air. Someauthors suggest that indoor plants are good as indoor air cleaners. Authors have studied the sinkeffect of indoor plants in unventilated closed systems. Unfortunately, the results from these studiescannot 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 forcarbon dioxide (CO2), formaldehyde (FAD), and total volatile organic compound (TVOC). Themeasurements have been made in two different climate chambers, a climate box of 0.56 m3 and aclean room of 19.6 m3. Both inlet and outlet air concentrations of CO2, FAD, TVOC, and content ofwater were measured. In addition the light intensity levels, lux and photoactive radiation (Par), weremeasured. The three following families of indoor plants have been tested: Epipremnum, Scheffleraand Spathiphyllum.A new method of measuring leaf area is described. The plant’s leaf area has been measured with aphoto scanner for a selected number of leaves and the relationship between the characteristic lengthand the area has been calculated using regression analysis. The characteristic length was measuredfor 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 acousticinfrared spectroscopy (PAS).Both single step and double step forward finite difference methods have been used for thecalculations of the indoor concentration dilution of contaminants. The latter method is preferredwhen using one single instrument and a switching valve for monitoring the concentration and gasflow from both the inlet and the outlet of the chamber. In the calculations the influence of thechamber 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 atday-time (500 lx) and that the source strength at night-time is 0.1 g CO2 m-2 h-1 when the inletconcentration of CO2 air is 400 ppm. If the inlet air concentration is 1500 ppm CO2 the sink effect islarger, ranging from -2 to -6 g CO2 m-2 h-1. The sink effect of FAD is in the range of -0.3 to -1mg FAD m-2 h-1 (at the background concentration of 0.3 mg FAD m-3), and the sink effect ofTVOCpas is -0.25 to - 0.5 mg TVOCpas m-2 h-1 (at the background concentration of 1-2mg 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).