Re-learning the Importance and Possibility of Natural Air Ventilation during Covid

By Regina Hoo

October 2021 FEATURE
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A postcard of the Penang Hospital. Photo by: Penang Philatelic Society

THE PENANG HOSPITAL1 began life as a double-storey, colonnaded brick-and-timbre building. As was the norm for most bungalows in Penang at the time, the building would have been raised on a brick plinth, allowing for air to flow underneath. The floors were probably hardy and washable, and tiled with terra cotta. The veranda on the first-floor was 5ft wide and protected by a jack roof, a feature developed by builder designers of the day in observance of tropical architecture.

“A jack roof,” explains conservation architect Laurence Loh, “is a secondary roof located at the ridge that is literally jacked up for the hot air within the space to rise up and escape through the open gaps between the two roofs, based on the principle that air, once warmed, becomes more buoyant, with a tendency to rise.” This process employs what is known as stack effect or ventilation. The surrounding cool air is pulled into the building from openings like doors and windows at the lower level, with the heated air being pushed up and out.2

The ground floor of the building would have been an open ward space, with a staircase to the first-floor located somewhere in the middle. This is conducive for cross-ventilation, a second principle that is critical in building designs for a tropical climate. Described as a natural cooling method, cross-ventilation relies on the difference in pressure between two sides of a building. Air gets drawn in on the high-pressure windward side, and expelled out through the low-pressure leeward side.3

The open plan ward would have been a very healthy space, which goes some way in explaining the research that went into its design, and for the building to respond resiliently to climatic changes, says Loh. “Unimpeded circular airflow was important in flushing out airborne diseases and infections. And if they had the resources, the building would have been supplemented with flat ceiling fans, but I doubt that in 1915, they had them.”

Another principle relates to the floor-to-ceiling height. Loh notes that the ceilings at the Penang Hospital was about 18ft high; to compare, the ceiling height of a typical terrace house stands at 14ft and a tropical bungalow’s is about two feet more. The orientation of the building to the sun forms the other basis. “The present Blocks B and C that front Jalan Utama are oriented east-west to minimise the exposure of the external vertical surfaces of the buildings to the sun’s rays, thus minimising heat gain through the walls.”

How Has the Hospital Evolved?

The current window design of the Penang Hospital.

Loh also draws attention to the “glass-like” windows in the photograph, explaining, “The thing I cannot reconcile is, when were they added in? They look to be modern, aluminium-like glass panes. Or else, the building would have been fitted with French doors.”

Certainly, reconfiguring the hospital to changing times has meant the adoption of modern means and designs. French doors were done away with, but the fixed louvers like those of existing shophouses remain. When mechanical ventilation was eventually introduced, by way of air conditioners and filtration systems, the structure of the Penang Hospital and its newer buildings had already deviated from responding to the clime through natural ventilation.

Today, consultation and specialist examination rooms are mostly air-conditioned, and are either windowless or fitted with single windows which do not allow for cross-ventilation to occur. Where social distancing is concerned, this is a recipe for disaster. Consequently, the air within becomes stale and without proper ventilation, traps dirt and bacteria, and can potentially expose both patient and doctor to Covid.

Managing the Pandemic

Photo by: Buletin Mutiara

When the virus was first detected in Penang, the 2m-distance between patient and doctor was adhered to, but time made lax this practice. At the waiting area, seats are marked “X” to keep patients one metre apart, but the overwhelming number of patients per clinic session has made such SOPs redundant.

“For Covid patients to successfully isolate, they would need to be placed in hermetically-sealed single rooms, assuming that space is sufficient, where the air is thoroughly cleaned and allowed to dissipate. But how does it get cleaned while one also makes sure the outside air isn’t contaminated?” Loh reiterates the air pressure theory, “The air outside needs to be pressurised so that it gushes into the room the minute the door is opened.”

Plans were initially made for the conversion of the student nurses’ quarters on Jalan Tull into a 200-bed ICU Covid Isolation Centre during the first wave; Loh oversaw its design and specifications. “It was to have positive pressure anterooms acting as air-locks at the entrances to negative pressure rooms, with two or four beds with piped oxygen.” Additionally, the internal air was to be filtered and scrubbed, and the virus neutralised before being released into the surrounding environment.

However, before the execution, Penang was announced Covid-free and the isolation centre never came to fruition. But now, as of September 8, Penang has recorded a total of 112,118 Covid cases4, with 119 BIDs (brought-in-dead) in the first eight months of 2021.5

To accommodate more Covid patients, the car park of Penang Hospital has been turned into a field hospital, with 96 ordinary beds and four ICU ones; utilisation of ICU beds in the state has reached 96.6% capacity, the second-highest in the country.6

Regina Hoo

is the deputy editor of Penang Monthly.