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Air handling units
MOFs are a new class of crystalline super-adsorbent These products can be used to improve indoor air quality by specifically targeting and capturing the carbon dioxide that can quickly build up in buildings
This is far from a trivial issue, particularly in education where the ability to concentrate is closely linked with future academic success. Research from Harvard University in 2016 found that, on average, a typical participant’s cognitive scores dropped by 21% when the room’s CO2 was increased by just 400ppm beyond baseline concentration. Critical response, information usage and strategy plummeted, all of which are key indicators of higher-level function and decision-making. Unsurprisingly these results also pose problems for the corporate workforce,
especially in countries where productivity is already low and the ongoing challenge of SBS costs businesses millions in missed working days every year. While the exact causes of SBS are still up for debate, some have identified the outgassing of materials from newspapers, furniture and building fabric as a possible candidate for the chronic symptoms people suffer, as well as volatile organic compounds released from things like aerosols, solvents and disinfectants. Fortunately, MOFs can also play a role here with their ability to capture specific problem molecules while bypassing others needed for good IAQ. Some might argue that simply opening the windows is sufficient, especially
when tackling CO2 build up in small classrooms. In many cases this will be effective, however depending on the season, natural ventilation may not be possible due to either very high or very low external temperatures. Likewise, in other environments such as large lecture theatres or office blocks, there won’t be any windows to open and fresh air will instead be provided through a fitted ventilation system. It’s also important to note that some inner-city buildings will also be found next to busy roads where outdoor air quality is poor and noise is high, so other methods will be necessary. As such, there are a broad range of everyday scenarios where fitted ventilation is the only way to refresh air while sustaining a comfortable and healthy ambient indoor temperature.
Efficiency
Using MOFs to improve air quality also has some added benefits for buildings with demand-control ventilation (DCV). These systems optimise IAQ through sensor- based airflow management, providing rooms with the right amount of fresh air
when it is needed. In an ideal world, DCVs would recycle 100% of the air they use but the CO2 that naturally builds up over time means more has to be introduced at certain times.
Introducing a MOF-based material into an existing DCV offers a route out of this problem. Building managers, for example, could easily retrofit their existing HVAC systems, removing CO2 without the need for invasive modifications to their existing system. The unique properties of MOFs allow them to be easily regenerated and reused, continuously removing CO2 and maintaining ideal conditions. The same principle also applies for air travel when air is recycled back into the passenger cabin during a flight. Perhaps the biggest benefit of this strategy, however, is the ability to reduce the
amount of energy used for temperature control during hotter months. A typical office building in the summer will use air conditioning to cool a room yet also have to introduce warmer outdoor air to ensure CO2 is kept with an acceptable range. With MOFs, though, more of the already-cooled air could be recycled back into the system without the need to worry about pollutants, in turn lowering the cooling duty and energy penalty incurred. This approach would prove especially effective in countries that experience longer periods of warm weather and rely heavily on HVAC systems. More attention is now being given to the air we breathe. This is not only due
to research that’s emerging but also the effect of the COVID-19 pandemic, which itself has helped to make an explicit link between indoor conditions and people’s health. With society slowly returning to something resembling normality, now seems like an ideal opportunity to explore better strategies for managing the air in offices, schools and other buildings where large groups of people meet.
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September 2021 17
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