The impact of Plants on IAQ – VOC

Case History

With respect to the issue of environmental health, it is recognised that plants can reduce the presence of some pollutants.
Nuvap studied the effects of plants on indoor pollution and has founded a positive relationship between the presence of plants and the reduction of some pollutants (especially VOCs). For this purpose an environment quality monitoring has been carried on and the environmental conditions have been modified in a controlled manner over time.

The monitored area

The observed environment is an open space office of about 50 square meters, with 12 workstations equipped with PCs, occupied from 8 am to 7 pm, with peaks levels from 9 am to 5.30 pm. In the office there is also a multi-function printer, in addition to 3 fan-coils, for heating and cooling. The room has natural ventilation. Daily office cleaning takes place between 6 and 7 am.

The test

The test lasted 10 weeks, from September 21 to November 29, 2019. This period was divided into 3 phases:

  • From 21/9 to 4/10 there were no plants in the monitored environment
  • From 5/10 to 15/11 3 plants were placed in the environment (about 1 every 15m2)
  • From 15/11 to 29/11 the number of plants was doubled.

3 varieties of hydroculture plants were chosen:

  • Dracaena Reflexa (h. 90-100 cm)
  • Clusia Rosea (h. 90–100 cm)
  • Elegant Schefflera (h. 90-100 cm)

The outcome of the test

During the test, the concentration of pollutants appears to be significantly affected by the presence of people in the office, as there is a progressive lowering environmental quality during the day, with a sensitive improvement over the weekend. 3 pollutants have shown greater variations during the period of monitoring: dusts, VOCs (Volatile Organic Compounds) and formaldehyde. VOCs’ dynamics are the most interesting. A difference of 13% in the value of the VOCs’ concentration has been observed between the first week of monitoring and the last one. Trend is evidently downwards, despite the heating from October 15th on.

The graph shows the weekly VOCs’ concentration data. The green bars show the concentration in the first week after the introduction of plants: on the 4th October the first 3 plants were introduced and on the 16th November 3 more have been added (doubling the number of each type of plant). In both cases there is an evident reduction in the VOCs’ concentration. The red bar indicates the concentration of volatile organic compounds in the week when the heating system has been turned on.

It is interesting to see what happens around this event: the week preceding 15/10 (date of switching on), there is an average weekly VOCs’ concentration of 216.86 ppB. In the following week, the average weekly concentration rose to 259.15 ppB, and then gradually declined in the following weeks. It takes two weeks before VOCs’ concentration returns to a level comparable to the week before switching on. The deterioration of the environmental quality is evident, but it is also clear that this effect is broken down by letting the plants act. The benefits are amplified when the number of plants increases.


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The project has been developed with HW Style, an Italian company founded in 1988, leader in design, realisation and green care for indoors and outdoors. The company started its business by supplying hydroculture plants for interior furnishings, then expanding its services with green and outdoor projects and events set-up, till the complete landscaping management. The team includes qualified designers and green specialists who work in partnership with prestigious Italian and international designers and architects. With a highly specialised staff of gardeners, HW Style manages, maintains and guarantees the green quality, carrying out all the ordinary and extraordinary maintenance operations.

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