This executive summary describes the extensive results for the monitoring of the indoor air quality parameters and microbial biodiversity in the CBRE IM building from May 2022 till March 2023. This pilot case is a result of the partnership and cooperation between CBRE Investment Management Netherlands and TakeAir.
- Microbial mapping of the building showed an overall very low microbial load in the tested offices. However, heavy fungal contamination of the filters in the air handling unit of “block I” was reported.
- The analysis of microbial biodiversity and community types showed that the indoor air of the offices in block G was enriched with beneficial microorganisms that were supplied via the central ventilation system by TakeAir’s BioRemediation technology.
- A drop in the relative humidity in Block G was observed when the volumes of AirProbiome were lowered, suggesting a possible link between BioRemediation and humidity. Further exploration of this encouraging inclination combined with the lower risk of infection when exposed to environmental probiotics could reduce demand for the high energy-consuming humidifiers.
- With the successful application of our developed measuring protocol, we achieved a milestone towards the next step in which we will connect the microbiome of the built environment with the well-being and productivity of the habitants.
- Finally, the analysis showed that even high-performing buildings such as Vattenfall, despite the overall extraordinary air quality standards may experience incidences or periods when the concentration of air pollutants exceeds healthy levels
Characteristics of CBRE IM pilot case
A heavily polluted environment with a national train station, highway nodes and a very busy event location (Bijlmer Arena) nearby. The event location especially is monitored to have a big impact on the grade of pollution of air quality. The location shows low to very low climate resilience and is prone to heat islands during high temperatures.
The New Amsterdam building in which the pilot case is located is redeveloped in 2013, the building itself is 25 years old but has been modernized to current standards.
Pilot case outlines
For the pilot case in the CBRE IM building blocks F and I was chosen as the reference locations, whereas block G was selected as a test location where the BioRemediation technology of the Biospheric Air Treatment was installed to introduce a blend of beneficial microorganisms (TakeAir’s designed microbiome called AirProbiome) via the central ventilation system.
Overall, the indoor air quality in Blocks G, F, and I is very good according to the European Environment Agency (EEA) guidelines, and most of the time meets the newest quality standards of the World Health Organization (WHO, 2021). Microbial mapping of the building showed an overall very low microbial load in the tested offices. However, heavy fungal contamination of the filters in the air handling unit of “block I” was reported.s
Main research activities in this project include:
- Custom design of particle removal technology based on flow dynamics modelling.
- Optimization and calibration of the biodisperser software parameters
- Installation of the air quality sensors and data collection
- Collection and analysis of the air and surface samples before, during, and after the installation and activation of the Biospheric Air Treatment
- Optimization of methods to analyze indoor air samples.
Results: Microbial Mapping & Relative Humidity
May 2022 - March 2023.
Microbial mapping and Bioremediation
Bioremediation is a process in which microorganisms are used to clean up a particularly polluted environment, e.g., soil and groundwater. Decontamination of air, on the other hand, relies on the incorporation of filtration solutions in HVAC systems. However, HVAC technologies decrease the transfer of pollutants from the outside to the inside and vice versa but they have no or limited effect on confining the dispersion of microbes derived from the human presence within the building. Probiotic or commensal microorganisms do not only positively modulate our immune system and improve allergy symptoms but can effectively inhibit the growth of pathogens and restore a balanced microbiome.
In this project, an assessment of the microbial indoor air quality, as well as microbiome biodiversity is performed using next-generation sequencing, enumeration on agar plates, and flow cytometry over several sampling campaigns organized.
Bacterial community types are an iterative clustering approach that groups samples together based on their phenotypic fingerprint (Figure 1). Bacterial community types in block F are the same throughout the locations, yet different depending on the sampling campaign. Those results confirm that the indoor microbiome is very dynamic, yet highly influenced by the HVAC system.
Figure 1. Bacterial community types among samples (no units). Coloured by sample location in the building and grouped by sample campaign. Horizontal axes are not constant and ordered by the numeric value of the community type.
Moreover, similar community types were found in blocks F and G prior to the activation of the BioRemediation system as well as 10 days after the introduction of the beneficial bacteria. However, in campaign 5, different community types were observed in the in-building sampling locations for block F and block G. Interestingly, in block G the 4th-floor ventilation grill sample exhibited the same community type as the positive control which is in line with the biodiversity results.
These findings are confirmed by a dimension reduction (Principal Coordinate analysis), which is shown in Figure 2 We see that the sample at the downstream nozzles is also quite related in community structure to the positive control. A clear difference can be observed between the samples in each campaign along the horizontal axis (as indicated by the dashed circles).
- We can observe that the samples of block G in the fourth sampling campaign are closer in community structure to the AirProbiome (control) samples than the ones from block F. With a clear clustering of the samples collected from the ventilation grill in block G (from the 5th sampling campaign), a sample from the downstream nozzle and the positive control sample.
- The results confirm that the air that is supplied to the offices in block G contains to a large extent beneficial microorganisms derived from AirProbiome and that their concentration indoors can be controlled by adjusting the volumes sprayed.
Figure 2. Community structure ordination (PCoA) of the bacterial community in the samples. Distance between samples shows relatedness. 38% of the total variance in the data is explained in the first two axes. Legend:
The reported relative humidity is within the recommended range of 40 – 60%, however, between December 2022 and January 2023 it drastically dropped in block F (Figure 3, data for block I is not shown). After a consultation with the technical support of Vattenfall, it was indeed clarified that the humidification system in block F was not operational from 08/12/2023 till 07/02/2023. Interestingly, both blocks G and F are operated by the same humidifier yet no drop in relative humidity in block G was observed, keeping the average at 55%.
Furthermore, despite the reactivation of the humidification, the real-time data shows that the set point values of 7.5 g/kg (which corresponds to approx. 54%RH) are still not met. The latter fact was also reported to the technical support of Vattenfall, and action has been taken. Interestingly, during the period when the humidification system was not operational and bioremediation of TakeAir was switched from higher spraying volumes (15 mL/h) to lower ones (4 mL/h) a slight drop in relative humidity was observed from 55.0 to 53.7% (Figure 7B). However, a longer monitoring period and more control over the humidification system are needed to confirm the influence of bioremediation on relative humidity.
Figure 3. Relative humidity in blocks G (blue) and F (grey) from May 2022 till February 2023. A) The period when the humidifier was out of order is marked in red. B) Dashed blue lines indicate the period when Bioremediation was active. The darker blue zone marks the time when a higher volume of AirProbiome was sprayed.
Users of buildings are commonly underexposed to the environmental, commensal microorganisms as seen in this pilot case. While many of the risks can be mitigated by the real-time monitoring of the indoor air quality parameters, to avoid exposure to airborne pathogens and their adverse health effects, the best practices include preventive measures such as establishing a resilient and balanced indoor microbiome by introducing beneficial microorganisms that will outcompete the potential pathogens and periodic analysis of common indoor air pathogens.
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