Best solution is Monitoring CO2 in closed environments -COVID19 and Indoor Air Quality in Classrooms

The below article brings to our attention the need for good ventilation within a Classroom or closed environment. To ensure Air Purifiers or open windows/doors are reducing CO2 levels, we need an instrument to monitor these CO2 levels.

The CEM DT-967 Carbon Dioxide Monitor is one instrument that can be utilized to make this measurement to ensure Students, Parents and Teachers can make the correct decision where required.

This article from The Sydney Morning Herald   

Classroom windows to be open so schools meet COVID-safe air standards

Students and teachers will have to put up with heat, noise and pollination in classrooms when school returns for some next week as new ventilation advice provided to the NSW Education Department says windows should be opened in all possible circumstances to mitigate COVID-19 transmission.

If windows are kept open at all times – including after lessons, over lunch and during hot weather or rain – independent modelling released on Tuesday shows the average public school classroom will meet global standards for fresh air changes and indoor carbon dioxide levels.

The department is also releasing 2200 school-level ventilation reports which are available to parents before students in kindergarten, year 1 and year 12 return on October 18. Other years return on October 25. They have divided school spaces into two categories: rooms that can have full capacity with their windows open, and rooms that need to implement the one person per four square metre rule.

For the latter category, which mainly affects staff offices, schools have been told how many people can be in that space safely.

Engineering consultancy Steensen Varming was contracted to provide independent advice to the department. It used guidelines from the World Health Organisation and the Harvard School of Public Health to gauge whether natural ventilation in classrooms met global standards for mitigating COVID-19 transmission.

The report assumes the typical NSW classroom has a 65 square metre floor area, 2.7 metre ceiling height, and accommodates 25 students and one teacher. It also assumes there are 3.25 square metres (or 5 per cent of floor space) worth of open windows – which is the standard that schools have been built to under construction codes – and that windows are positioned on one side of the room, which is a worst-case scenario.

“There are obviously numerous variables that would need to be considered … However, known industry tools have been used to estimate likely [air changes per hour] of natural ventilation together with conservative assumptions of some variables for a typical classroom,” the report says.

The calculations indicate classrooms will achieve the main benchmarks of fresh airflow: there would be six air changes per hour and carbon dioxide levels would be about 726 parts per million, which is safely below the accepted threshold of 850. When the number of students in the room increases to 30, estimated CO₂ levels are 772.

“The typical classroom satisfies and exceeds the WHO road map first strategy approach of providing the nominated fresh air ventilation rate of 10 [litres per second] per person. Additionally, the results also show satisfactory CO₂ levels in the typical classroom,” it says.

Education Minister Sarah Mitchell said the Steensen Varming report would allow schools to implement expert ventilation advice at a classroom level.

“Parents can be assured that everything is being done to ensure schools are safe for students,” she said. “We need to listen to the experts when it comes to ventilation, just as we do with vaccines.”

Steensen Varming said there was no “zero risk” scenario and that some of its advice may not apply to all school buildings, while issues such as hot weather had not been accounted for.

“As we are currently in spring external temperatures are mild and favourable for natural ventilation. However as we approach summer, and with rising ambient temperatures, the reliance on natural ventilation will lead to thermal comfort issues in classrooms,” the report says.

Classrooms that use air conditioning units on hot days will still need to keep their windows open, meaning rooms will not be as cool and students may be less comfortable.

High outdoor air pollution or pollen levels, loud outdoor noise for schools near construction sites or under flight paths, and security concerns might also affect a school’s ability to open windows. “If it is windy, hot, cold or raining then it may not be practical to fully open the windows or vents,” the report says.

But in all cases the advice says the “highest tolerable” amount of outdoor air should be used, even if it means students and teachers have to adjust their clothing to be comfortable: “[Windows] should be open as far as reasonably possible without causing intolerable discomfort.”

The report also says that wind pressure and certain temperatures – two factors that ensure successful natural ventilation – will inevitably vary based on weather, the position of the classroom and its windows, as well as obstructions like mesh or fly screens.

School Infrastructure NSW chief executive Anthony Manning said the design criteria governing the state’s schools with regards to window sizes meant classrooms would generally have all the fresh air they needed. His team will be working with schools in coming weeks as they adjust to the new edict.

“We’ve said to schools, you can run your wall-mounted air conditioning systems [for heat], you just have to run them with the windows open. They won’t be as effective, but they will provide some level of comfort. The idea is we’ll work with schools to understand all those issues [such as heat and noise] and find alternative ways of doing it,” he said.

The department is also sourcing about 10,000 air purifiers that schools can use if natural ventilation is not sufficient, or in the event of bushfire smoke or poor air quality.

The state’s infrastructure staff are finishing maintenance tasks before all students return on October 25. This includes fixing window frames that have been painted shut and fitting mesh or restrictors on windows above ground level so they can open safely.

This article from The Sydney Morning Herald   

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