You are what you breathe. Keeping buildings Covid-free.

May 14, 2020

Ventilation is now a hot topic. As architects, we urgently need to know which vents to trust in our buildings. Recent research points at Covid 19 surviving in airstreams for quite some time.

It was great to hear Owen Connick, an expert in the field, both as a manufacturer and consultant, say last week that best practice in new construction is “openable windows in all places”. Ash Sakula is a believer in user control and keeping buildings within the parameters of natural ventilation. The LCB Depot, pictured, converted an existing bus depot into studios for creative business. Air conditioning and mechanical ventilation was avoided. Each studio was naturally ventilated and the deep plan building was hollowed out with a new courtyard lightwell to enable cross ventilation.

But of course it is complicated by the levels and variety of poisons we have to face. Indoors, burning toast, cleaning the floor or bathtub, buying the wrong kind of carpet or furniture can leave VOCs attacking the health of occupiers. Traffic fumes, nasty particulates, even fluff off trees at certain times of the year, mean that opening a window does not necessarily bring in fresh air. Noise from outside  might slowly decline with the increasing use of electric vehicles, but noise break out between uses when we want to intensify the occupation of buildings is set to rise.

As we become more conscious of air and how it affects our health, our tactics as designers may need to change, not just because the science is throwing up new facts, but because our relationship to the unseen parts of buildings will change. Maintenance of dirty pipes, wires and ductwork is well-nigh impossible.What we cannot see and control can lead to anxiety. Just as the city challenges us to reassess and rebuild our psychogeography of place and navigate its complexities, buildings do that at a different scale. Individuals may come to favour buildings of simplicity which they can ‘read’. Institutions, unable to predict future use, may choose to respond to the dual challenge of health and climate emergency by commissioning simple, low-tech, passive buildings which will not require their innards to be replaced every few decades.

One way to do this is to return to older narrower buildings, and we’ve been trying to pin down what the possible motives and consequences of reinstating a finer grain might mean. In discussion we found compelling technical reasons for reducing the depth of our floor plates, both in building new and, importantly, in retrofitting existing structures where tactical demolition could give buildings a new lease of life:

1.     Hybrid ventilation systems, whether MVHR or NVHR, involve recirculating air and intricate webbed ductwork: this might need rethinking as ductwork is well-nigh impossible to clean: not so good when decontamination is prioritised.  Instead floor layouts will allow for perimeter ventilation with room heights over 3.5 m to allow for ventilation through openings at high level. In highly insulated buildings, even in winter, the model works so that air descends slowly and mixes comfortably above people’s heads.  

2.     Modern school buildings and offices often rely on the use of cross talk attenuators to allow air to percolate from a naturally ventilated perimeter room to an internal space without compromising the acoustic performance of the wall.  However, the use of sound absorbent material to the lining of the cross talk attenuated box raises the risk of all air passing over potentially contaminated rockwool and other hidden surfaces.  Instead pocket courtyards and re-entrant facades can bring air directly into the deeper parts of the building and ventilate rooms on noisy facades. The big box has gobbled up so many building typologies in recent times, as the rational cost effective solution: now other considerations and rationales may come into play.

3.     Lighting has become the number one energy-hungry use in buildings. Lighting is centrally controlled and often left on 18 hours a day. The mental health issues with deep plan buildings are now well established; employers and anyone with a duty of care including investors will need to be concerned about deep plan’s deficit of daylight coupled with increasing climate risk. So larger windows, intelligent age-old cross ventilation and large shady trees so useful for mitigating solar gain but long held back from buildings will all play a part in changing the lighting dynamic of interiors, while longer perimeters will deliver gains in intensity of use.  

Perhaps we should rely less on buildings to do it all? While buildings will always act as the outermost skin in creating indoor comfort, should we not each then play with our own layers to refine our own microclimate?  Less formality in office garb might open up a new era of expression through our clothes, the wools, the cottons, the silks, the variety of manmade fibres and breathable tech, the upbeat darned jumpers and upcycled concoctions can make keeping warm and staying cool an artistic endeavour.