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23 July 2021updated 14 Sep 2021 5:07pm

The post-Covid building

Ventilation plays a key role in preventing airborne infections like Covid-19 but improving it may come at a cost

By Samir Jeraj

Even after the Covid-19 restrictions in the UK wind down, the office may never quite return to the old normal. Inside buildings and workplaces, desks have been distanced, plastic barriers placed around receptions, and whole new sets of procedures are now in place to manage the challenges of the pandemic. One of the greatest of these is how to safely and effectively ventilate buildings to prevent airborne infections while keeping the energy cost down.

This is not the first time that people have turned to natural ventilation in order to protect against disease. In the 17th century, following the Great Fire of 1666, the Old Bailey courts in London were rebuilt to be in the “open air” to prevent the spread of typhus, while “miasma” or “bad air” was similarly wrongly identified as the cause of the bubonic plague in the same era. In the early 20th century, steam heating systems designed to circulate fresh air were installed throughout cities in the US – particularly New York – following the Spanish influenza pandemic.

But following the energy crisis in the 1970s, the cost of energy rocketed and buildings started to be sealed up in order to keep costs down. The unintended consequence of that is that the air quality inside buildings became very poor (this was still an era when people routinely smoked in their workplace) leading to what was termed “sick building syndrome”. Hence came the move for ventilation to deal with these issues, and since then it has been a balancing act between energy and effectiveness.

“Ventilation has been ignored for a very long time,” says Benjamin Jones, an associate professor at the University of Nottingham, but adds the pandemic has prompted a surge of interest in the issue. Andrew Eddy works on this problem for Verto’s new-build Zero-Carbon homes, as head of innovations and sustainability. The homes use mechanical ventilation with a heat recovery system, which works for buildings that have a well-insulated and “fairly airtight” structure – this means relatively little uncontrolled heat loss or air loss, he explains. The system then pumps air from outside into the home through a filter while removing it from other places in the home where moisture gathers and where there is the greatest risk of problems such as mould.

Poor indoor air quality can lead to, at the most dangerous end, health risks such as carbon monoxide, which can kill, or at the other end of the scale, persistent bad smells that make living or working environments unpleasant. “That’s the best rule of thumb: if you walk into a room from the outside and it smells bad, it’s under-ventilated,” says Jones, and that means the infection risks from airborne disease are higher.

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Filters can be installed to ventilation systems to screen out airborne virus particles, but it is problematic, Jones explains, because there may not be space for them in the system: “There will be a lot of resistance to airflow, and so if the fan power isn’t increased the ventilation rate will fall. It’s like breathing through a mask; it’s harder.” There are also leakage issues if they are installed badly. “Because they resist airflow, the air will take the path of least resistance and will flow around it, negating the benefits of the filter,” he says.

Persistent bad ventilation over a lifetime leads to health issues, such as chronic obstructive pulmonary disorder. A report published in 2020 by the Royal College of Paediatrics and Child Health recommended national action to improve indoor air quality to prevent children from developing issues ranging from respiratory and skin conditions to hyperactivity and poor school attainment.

Jones would like to see changes to building regulations to help promote better air quality. While school buildings are really well regulated, he says, homes are still governed by a set of standards that are not fit for purpose. Something as simple as requiring kitchens to have a cooker hood fan installed in new homes and as part of any refit would have a significant impact.

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“We’ve seen a massive increase in requests for natural ventilation during the pandemic,” says architect Thomas Jepson, founder of Passion Plans. He feels this demand is as much about concerns around sustainability as well as the impact of Covid-19. When harnessed correctly, natural ventilation can significantly lower heating and cooling bills and ensure the future of the planet.

Each project has its own needs depending on the local climate, Jepson continues. “Beach homes will take advantage of the breeze coming from an onshore direction. Mountain homes will take advantage of the wind rolling downslope,” he says. Rooms and even windows can be designed to better promote air quality. However, natural ventilation does have its challenges, he acknowledges, particular in very hot, very cold or humid environments, where ensuring the appropriate temperature, flow of air and protecting against mould all become more difficult with natural ventilation alone.

Some companies and organisations have their sights set on an even more ambitious task than ensuring the safety of the air inside buildings. “It’s more than cleaning the air – that next step is making that air healing or healthy,” says Jo Pannecoucke, the founder of Take Air, a Belgium-based company that has developed add-on filter technology that uses biology in order to actively improve the quality of air alongside removing airborne dangerous infections. Take Air claims to have solved the problem faced by filtering systems – that the more effective they are, the more energy it takes to push the air through the system and through the filter.

“The missing link for us was biotechnology,” says Pannecoucke. The team at Take Air looked at what micro-organisms could be safely part of their technology to accomplish their goal of creating healthy air, making the link with other products that include “healthy bacteria”. “At that time if you talked about bacteria everyone was running away!” says Pannecoucke. While traditional filters would see the air pressure drop significantly, Take Air’s system produced a negligible fall.

After nearly five years of work to test and develop the technology, Covid-19 shut down the world but also underlined the importance of airborne infections. “We had never heard about Covid – we were working on influenza,” Pannecoucke says. The team tested their system on Covid-19 over the next 18 months and came to the conclusion it was effective at stopping it too. “We have been testing and working on a system that on the one side is catching and killing viruses, including Covid, and on the other side is doing what we started to do and rebalancing the air to a healthy microbiome balance,” says Pannecoucke.

Previous pandemics prompted massive changes in the built environment, using natural ventilation to open up buildings, towns and cities to encourage fresh air flow. Covid-19 has already forced change in how and where we work. Whether there will be a move back towards natural ventilation and the likely greater energy costs, or new technology will arrive to improve the safety quality of air inside buildings, remains to be seen.

This article originally appeared in our issue on Biotechnology: The breakthrough sector. Download the full issue here.