Investigation of HVAC Operation Strategies for Office Buildings During COVID-19 Pandemic

To minimize the indoor transmission of contaminants, such as the virus that can lead to COVID-19, buildings must provide the best indoor air quality possible. Controlling indoor air quality is largely achieved by running the building’s HVAC system to dilute any concentration of indoor contaminants. However, doing so has practical downsides on the HVAC operation that are not always quantified in the literature. This paper develops a temporal simulation capability that is used to investigate the indoor virus concentration and operational cost of an HVAC system for two mitigation strategies: 1) supplying 100% outdoor air into the building and 2) using different HVAC filters, including MERV 10, ASHRAE minimum-recommended MERV 13, and highly rated HEPA filtration. These strategies are applied to a hypothetical medium office building consisting of five occupied zones and located in a cold and dry climate. We modeled the building using the Modelica Buildings library and developed new models for HVAC filtration and virus transmission to evaluate COVID-19 scenarios. We show that the ASHRAE-recommended MERV 13 filtration reduces the average virus concentration by about 10% when compared to MERV 10 filtration, with negligible additional operational cost. In contrast, the use of 100% outdoor air or HEPA filtration reduces the average indoor concentration by about an additional 3% compared to MERV 13 filtration, but significantly increases building operational cost. This is due to the significant increase in energy consumption when supplying 100%outdoor air and the higher cost of purchasing a HEPA filter.

TVOCs and PM 2.5 in Naturally Ventilated Homes: Three Case Studies in a Mild Climate

In southern Europe, the present stock of social housing is ventilated naturally, with practice varying in the different seasons of the year. In winter, windows are kept closed most of the day with the exception of short periods for ventilation, whereas the rest of the year the windows are almost permanently open. In cold weather, air changes depend primarily on the air infiltrating across the envelope and when the temperature is warm, on the air flowing in through open windows. CO2, PM2.5, and TVOC concentration patterns were gathered over a year’s time in three social housing developments in southern Europe with different airtightness conditions and analyzed to determine possible relationships between environmental parameters and occupants’ use profiles. Correlations were found between TVOC and CO2 concentrations, for human activity was identified as the primary source of indoor contaminants: peak TVOC concentrations were related to specific household activities such as cooking or leisure. Indoor and outdoor PM2.5 concentrations were likewise observed to be correlated, although not linearly due to the presence of indoor sources. Ventilation as presently practiced in winter appears to be insufficient to dilute indoor contaminants in all three buildings, nor does summertime behavior guarantee air quality.

Indoor Contaminants in Chemical Laboratories: Characteristics of BTEX by Environmental and Biological Monitoring

BTEX (benzene, toluene, ethyl benzene and xylenes) are the most important categories of VOCs that occur in the indoor air and often used in chemical laboratories. In the present study the excretion of urinary BTEX were evaluated as biomarkers of exposure to these compounds. The mean value of benzene in breathing zone and the total benzene uptake during the work shift of the two groups of technicians and students in chemical laboratories were 32.11and 46.82 µg m-3 and 14.55 and 34.11ngL-1 , respectively, which were significantly greater than the occupationally non exposed groups. Good correlations (0.839 ≤ r ≤ 0.946) between the mean values of BTEX in breathing zone and the urinary concentrations were observed.

Correlation amongst Indoor Air Quality, Ventilation and Carbon Dioxide

The calculation of carbon dioxide (CO2) intensities can be employed to see the quality of indoor air and ventilation. The studies undertaken till date have been distorted. The current study summaries the association amongst carbon dioxide and building air quality and ventilation, with carbon dioxide being the marker to evaluate air quality and ventilation performance. High carbon dioxide intensities may show insufficient ventilation per occupant and high indoor contaminants intensities, resulting in the Sick Building Syndrome (SBI) Symptoms. The researcher assessed the literature related to indoor air quality (IAQ), ventilation, and building-linked health issues in schools linked to CO2 discharges and recognised general indicated building-linked well-being signs found in schools. A high rise in the ventilation rate or enhancement in ventilation efficacy and/or indoor contaminant source regulation would be anticipated to reduce the occurrence of chosen signs to its optimum.

Badania nad występowaniem węgla w powietrzu wewnętrznym wybranych uczelni w Polsce

The research presented herein aimed at recognition of submicrone particulate matter concentration as well as organic (OC) and elemental (EC) carbon bound to it in a lecture room and students’ laboratory. The 24-h variability of PM1, OC and EC concentration in both rooms were also discussed along with I : O ratio. In the analysed period – the turn of spring and summer – independent of the location (Gliwice – students’ laboratory, Warsaw – lecture room) the indoor concentration of elemental carbon EC was conditioned by the intensity of those contaminants migration along with atmospheric air. Because of this, it can be concluded that in neither of the rooms there was an important source of OC and EC. However, it should be noted, that conditions favourable for different contaminant sorption, in particular those belonging to OC bound to particulate matter, vary in time and space. It is expected, that for other measurement period – for instance in winter, when rooms are ventilated seldom and PM has different composition, the cummulation of indoor contaminants, including OC, may be higher than for warm period.