Wotton Works benefits from three state of the art MVHR units (Mechanical Ventilation Heat Recovery), providing fresh air and wellness to its occupants. Herewith is an article that appeared in the Times in September 2021 advocating the benefit of good air quality.
Ventilate! Ventilate! Ventilate! How to design breathable buildings of the future. We have finally woken up to the importance of airflow in stopping the spread of Covid. Now we need to draft plans for homes offices and schools that won’t make us sick.
When Lidia Morawska goes out for dinner near her home in Brisbane, she takes with her all the essentials: keys, phone, mask — and her carbon dioxide monitor. She puts the device on the table next to her wine glass and waits anxiously for a reading. The monitor essentially measures how much breath there is in the air. We exhale CO2, so a higher reading indicates more breath, acting as a proxy measure of ventilation and the potential transmission of airborne viruses, including Covid-19.
Even in a busy room, Morawska, a pioneering aerosol scientist at Queensland University of Technology, says good ventilation results in a CO2 reading close to background levels — the amount you’d expect to be there if there weren’t people inside. At one restaurant last year, Morawska and her husband got a reading of more than 2,500 parts per million (ppm), the highest she has seen. It wasn’t a mild evening, but she immediately asked to be seated outside. The 68-year-old professor has previously studied Sars outbreaks and knew immediately at the start of last year what it took some authorities months to accept: that Covid-19 is an airborne virus and the risk from aerosol transmission was many times higher than that from large droplets on surfaces. She was despairing of early public health messaging, including such slogans as “Wash your hands, save lives” and “Hands, face, space”. What slogan would she have issued? “Ventilate! Ventilate! Ventilate!” she says.
Now, as winter approaches in the northern hemisphere, and workplaces, buses and trains get busier, scientists including Morawska are warning that our ventilatory defences are still low. “There’s a storm and we are still putting buckets under the leaking roof,” she says from her home office, where, with windows and doors closed, the CO2 reading is 669ppm. For decades we have aspired to cocoon ourselves in double-glazed, draught-free homes. Good insulation has become vital in the fight against the climate crisis. But too often, cosy homes, as well as shops and restaurants, are as good as sealed boxes: Petri dishes for transmission. Opening windows helps combat Covid-19, Morawska says, but it isn’t great if kids have to wear coats in school or we burn fossil fuels to keep ourselves warm, only to spew hot air out into the sky. The good news is that the longer-term fix is not rocket science.
“We have the technology, we just haven’t prioritised it,” says Orla Hegarty, an architect and assistant professor at the architecture school at University College Dublin. Hegarty, who has several CO2 monitors, designed her own house, long before Covid-19, to include mechanical heat-recovery ventilation. When natural ventilation — windows and vents — isn’t viable, such systems, which can be retrofitted, extract used air and send fresh air back in via a heat exchanger, which retains indoor warmth but nothing else. The technology uses a lot less energy than air-conditioning, and Hegarty says well-ventilated homes need not carry a greater financial or environmental cost. If anyone comes to her house, Morawska opens windows and doors, checking her CO2 monitor to make sure it’s working. When it’s cold or smoggy outside, the professor also recommends good-quality air-purifiers, which draw air through a filter, sifting out particles, including viruses, at a relatively low cost. Hegarty spares most of her concern for badly designed, overcrowded spaces, including social housing. She is lobbying for stricter building controls to include basic ventilation, including heat-recovery systems. Studies have shown that Covid-19 can pass between flats, sometimes across poorly ventilated corridors, without people ever sharing a room.
“If we sort out indoor air quality, the reproduction [R] rate wouldn’t even be high enough to create a pandemic,” says the architect, who has investigated the role of buildings in this and previous outbreaks. She says improving ventilation has a knock-on effect on other airborne viruses, as well as damp. She blames deregulated cost-cutting developers for ignoring the common-sense approaches to ventilation that have traditionally informed architecture. So-called permitted developments, including the conversion of offices into shoebox flats, have already been criticised for leaving residents vulnerable to heatwaves. Ventilation is often an afterthought, at best.
“In some institutional housing, the R rate has been something like 10 or 15,” she adds — meaning one infected person transmits the virus to as many as 15 others. “We need to target those buildings first.” She compares the neglect of good ventilation to the use of cheap flammable cladding on Grenfell Tower. Hegarty and Morawska share a deep frustration that it has taken so long for the world to wake up to the importance of aerating indoor spaces. The UK government acknowledged the importance of ventilation by late 2020, but only issued guidance last March — a full year after the first lockdown. This included advice on opening windows, as well as making sure vents and extractor fans are clear and working. There was no mention of CO2 monitors, which were only provided to schools this month thanks to £25 million of government investment.
Transport is also a concern, particularly as the commute returns. Morawska advises opening train and bus windows where possible. “But if you’re packed like sardines, you are exposed to very high risk, even if this ventilation is excellent,” she warns. “In this situation, the only solution is a very good mask.” She compares the push towards better ventilation to pioneering work in 19th-century Britain to construct sewers. If we can plumb clean water into our homes and get rid of the dirty stuff, why not air too? Morawska has led an 18-month global campaign, involving leading scientists, architects and engineers, to encourage the world to wake up to the importance of aerating indoor spaces, and is credited with convincing the World Health Organisation belatedly to recognise Covid-19 as mainly airborne — work that last week earned her a spot on Time magazine’s list of the 100 most influential people. “It’s definitely the first time I’ve shared space with Meghan Markle,” she says. “It’s nice to be recognised, but if I am happy, it’s because I now have hope that something will change.”
Pub covid case study
A 25-year-old man with Covid-19 walks into a pub. He has not yet started feeling any symptoms but the Sars-Cov-2 virus is replicating fast within his body. All of the tables have been sanitised, although the chance of catching Covid-19 from surfaces remains very low. The pub is table service only, and nobody can sit at the bar. He sits down and takes off his mask. Every five seconds he exhales. Each breath contains roughly 800 millilitres of air and 1,000 copies of the virus.
He sits at his table for an hour, in which time he exhales 600 litres of air containing 720,000 copies of the virus. The pub, which measures 10m x 10m x 3m, contains 300 cubic metres of air. With no windows open and no ventilation, the virus gradually fills the room. Within an hour, each cubic metre contains roughly 2,400 copies of the virus. As the evening progresses, the number of punters grows. There are now 46 people in the pub: 40 customers and six members of staff. Two thirds have high levels of immunity, either from being vaccinated or having caught Covid-19 in the past.
After an hour, let's assume 17 people have caught the virus. Of the two people sitting at the same table, one is vaccinated and does not become infected, but the other receives the highest viral load and is the first to become infected. The hospitality trade knows there are many ways of making indoor dining and drinking safer. If one large window is opened, depending on wind speed and temperature inside and outside the pub, the air in the room is replaced three times an hour.
After 60 minutes 14 people are infected, compared to 17 when all windows are closed. Those sitting next to the windows are safe. If two windows are opened on opposite sides of the room, allowing a light breeze to flow through, the air is replaced 15 times an hour. Only six people are infected. Studies show that only one case of Covid-19 in every 1,000 is contracted outdoors. If the infected man sits outside, nobody is infected.