ACR Journal

CMYK / .ai CMYK / .ai CMYK / .ai acrjournal.uk 19 INDOOR AIR QUALITY useful measure of how adequate ventilation levels are. Our team analysed more than 9.2 million sensor readings across the five schools over the academic year with some staggering headline results. With sensor sampling frequency every five minutes, the data covers classroom hours only, between Mon 6 Sep 2021 and Wed 27 July 2022 and excludes holidays. The highest recorded CO 2 reading of 5,966ppm (parts per million), is a staggering 4,466ppm above DfE guidelines of 1,500ppm. However, the average classroom CO 2 reading across all classrooms in the five schools over the whole academic year was 959ppm, which as a stand-alone figure looks fine, but the total number of hours spent over 1,500ppm was 4,846 which is far from ideal. The Airthings indoor air quality monitors we used include a CO 2 alert that lets you know when carbon dioxide (CO 2 ) levels get too high. Over the academic year, across the five schools the total number of CO2 alerts over 1,500ppm was 57,599. This alerted teachers to bring fresh air into the room by opening windows and doors where possible, however, during the winter months it proved di cult to keep classrooms warm enough when windows were open, and the CO 2 data on cold days backs this up. Ideally, schools need ventilation systems retrofitting that will increase ventilation levels by bringing in filtered outdoor air to dilute the stale air indoors. Year 2 study on PM2.5 We’re not done yet, as CO 2 is only part of the problem. The Evotech team continue to work with the five Calderdale schools and together, during Year Two (September 2022 to July 2023), our focus is on Particulate Matter (PM), a serious air pollutant that can be inhaled deep into the lungs where it can cross into the bloodstream and cause serious health problems. The data is already showing trends of high PM levels and, as four of our five #CleanAirSchools are in old buildings with natural ventilation, and within close proximity to busy roads, opening doors and windows is not the best solution. The solution Ideally all schools would benefit from a modern HVAC system as they are able to heat or cool the incoming air, ensuring indoor environments are optimised for comfort, as well as the health and wellbeing of building occupants. When these systems are managed by a building management system (BMS) connected to a series of air quality sensors, temperature and ventilation levels can be automatically adjusted per room or zone. Also, when parts of the building are not in use (very low levels of CO 2 ) energy can be reduced by automatically turning o lights and reducing heating or cooling in that part of the building. Overall, significant cost savings can be made whilst reducing energy consumption and CO 2 emissions. However, we don’t live in an ideal world and retrofitting HVAC systems is a costly outlay, funds that schools simply don’t have. But the opening of windows and doors is not a long-term solution for any school. In areas with high pollution levels some ventilation methods – like the opening of windows – may allow the ingress of outdoor pollutants like NO2, VOCS and PM. In these instances, air purifiers can help as a short term solution until the building’s ventilation is improved. Air purification units should incorporate a HEPA13 filter as a minimum, that will capture 99.9% of particulate matter down to 1µg/m³ (micrograms per cubic meter of air), and use a high grade activated carbon filter to reduce VOCs and NO2. As air purifiers cannot filter out CO 2 , it’s important that ventilation is improved in the long term to help increase productivity and learning outcomes. So, the outcome of the study is that old school buildings are, in general, poorly ventilated and need ventilation systems installing. Costs that could be o set by reducing energy costs, and such systems would have the added advantage of reducing carbon emissions and therefore helping the Government reach its net-zero target by 2050. Download the full report here: https://www.evotechairquality.co.uk/ classroom-co2