From now on, people are going to be much more concerned about the quality of the air within their space. The virus has focused attention on the role of air-handling systems in spreading infection, and the implications of recirculating air. We will have to be much more deliberate in our approach to achieving good air quality within commercial buildings – this will be one of the most important engineering decisions for offices going forwards.

To reduce energy, air-conditioning in offices limits the level of filtration and the proportion of outside air brought into a space to a minimum that is deemed sufficient to clear odours and freshen up the space.

In hospitals, critical spaces such as operating rooms or ICUs are fitted with high-level filtration and have the ability to be ventilated with 100% outside air. In an operating theatre, the air will be changed 20 times in an hour. Within an office environment, it might be changed only twice.

A pandemic is not a regular occurrence, but it is still a possibility.

So we have to design with caution, and make sure that the air within an office space is of higher quality. It may be cost-prohibitive to move to 100% outside air everywhere because it means cooling or heating a large amount of air each time, but we should have the ability to convert systems, or to add extra levels of filtration. Air distribution systems could be designed to have a second operation mode, so that they can easily be retrofitted if we face a similar scenario in future.  

We will need sensors that allow us to understand air quality within a space

– not something that is usually fitted within an office environment – or routine weekly or monthly testing. We do now design to limit levels of toxic VOCs and formaldehyde, but now we have to add new design criteria to monitor the level of contamination and bacteria within a space. Building codes and guidelines will need to be updated too, to set an acceptable level of contaminants for habitation.

The quality of air distributed into a space depends on the equipment that is used.

We also need to look at the lifespan of air handling units and other equipment that serves office environments. Often this is allowed to degrade due to a lack of routine maintenance, and filters are not changed regularly, diminishing their efficiency. Sometimes building owners don’t replace equipment when the service life is exceeded because of cost. Instead, they try to find some remedial way to lengthen its life, or they just hope for the best and wait until it fails. With age comes rust: metallic surfaces inside older air-handling units are no longer protected and the rust enables them to harbour greater mould growth and bacteria. This is carried into the ductwork, and then into the space. 

We also have to look how often we clean ductwork.

A building is there for perhaps 20 or 30 years and the ductwork is only cleaned at the start, or during renovations. When you’re doing a survey or you rip that ductwork apart for renovations, that’s when you understand how poor the air quality can be. For new systems in office environments, engineers write a specification that instructs the contractor to have the unit fully cleaned before it is handed over, though most don’t do this. That’s something we have to enforce on the construction side. On the operation side, we have to enforce some routine cleaning and sanitizing of ductwork as well – I would recommend that this is done at least quarterly.

In laboratories, all these things are routinely tested.

The air has to meet certain ISO levels – in order for experiments to work, it has to be of a reliable temperature or quality. I always think, if we can do that for chemicals or scientific equipment or laboratory animals, why wouldn’t we do it for people?