Healthy Architecture Design
Patrick Lau 劉秀成
Covid-19 has revealed the need for new approaches to building hygiene. Architects and designers must now urgently consider the hygiene and control responses to the problems that may arise from future pandemics, while bearing in mind that there will be no simple answers to future architectural design solutions.
Research institutes can help by setting design objectives for architectural improvements aimed at preventing or curbing virus outbreaks. Measures they could look at include: ensuring buildings have adequate daylight and natural ventilation; revising space configuration and occupant density levels; orienting building sites, windows and doors appropriately; ensuring the optimal opening sizes and glass type; installing sensors in controls that minimise human contact, and installing virus detection and control systems at building entrances where possible; increasing air-change rates in ventilation systems; installing systems adjustable to meet the needs of different activities; as well as maintaining indoor humidity levels at 40-60%.
After analysing various cases of indoor group infections, mechanical engineer researchers at the University of Hong Kong have found that poor indoor ventilation can exacerbate the spread of viruses. While it is commonly known that maintaining a safe social distance can help lower the infection risk arising from the airborne transmission of viruses, it is less apparent that ventilation quality might change what a ‘safe’ social distance actually is. For short-range airborne transmission, droplet concentrations exhaled from an infected person typically become indistinguishable from background room air after travelling just 1.5 metres. However, cases have been found where infection has still been possible across distances of up to 9.5 metres. Researchers have concluded that ventilation is a contributing factor in turning short-range airborne transmissions into such longer-range transmissions. Consequently, it is suggested that buildings should maintain a ventilation rate of 8-10 litres per second per person in order to avoid airborne transmission of Covid-19 in any indoor environment – a figure well above the standard recommended by ASHRAE 62.1 of at least 5 litres per second per person.
The key to sustainable architecture is to address ‘Heaven, Earth and People’ in architectural design, and it is also my belief throughout my architectural practice.
During the 1960s, Hong Kong buildings were designed with open corridors and courtyards so as to suit the local sub-tropical climate with its hot, humid summers. Building regulations encouraged the use of light wells for natural lighting and ventilation. That allowed sunlight to penetrate buildings and air flows to carry away unwanted elements. Now, however, with the extensive use of air conditioning, buildings are sealed off leading to the continual recycling of air and with it the creation of a new source of health hazards.
The Sam Tung Uk Museum project reminded us of the good architectural practice in the past. Located in a former walled village in Tsuen Wan, The village comprised three rows of courtyard houses oriented to take full advantage of natural sources of light, ventilation and humidity control. The village’s four main houses are surrounded by side houses accessed through open corridors. The last of the three rows housed the village’s ancestral hall, a well-protected structure with no exterior windows.
Each house was built with sun-dried mud bricks, making them well insulated from heat. For reasons of privacy and protection from attack, they have few windows. Granite, chosen for its durability, was used to edge corners on walls and for courtyard paving. Doors are tall, partly to allow for better ventilation of the buildings’ small courtyards. Roofs are made with timber rafters and battens supporting clay tiles. Glass tiles were used occasionally as skylights. The use of courtyards for natural lighting and ventilation are essential elements of Chinese Architecture.
The Sam Tung Uk Museum project inspired three subsequent projects in the application of Vertical Courtyard concept.
The HKU SPACE Community College (Kowloon East Campus) located in Kowloon Bay was completed in 2006. It stands on a small site granted to the University of Hong Kong in Kowloon Bay, a former industrial area of Hong Kong. Its design, the winning entrant from a closed competition, features a series of vertical courtyards linking facilities such as classrooms, labs, library, computer rooms and offices with rooftop sky gardens by stairs and escalators open to the sky. With an empty core, natural sunlight and ventilation can penetrate the entire building. At roof level, a skylight steel structure opens on all sides to allow hot air to rise through the building’s atrium space. The convectional drafts that arise carrying unwanted elements such as viruses out of the building. Although each internal space also has its own air-conditioning control system, overall this natural ventilation system allows the campus to use less electricity than any other University of Hong Kong building.
The Hong Kong Institute of Vocational Education (Shatin) Learning Resources Centre produced a unique solution on sustainable design. An existing courtyard structure with fully grown trees left little room for expansion. However, inspired both by traditional Chinese academy architecture and the idea of harmonising human identity with the gracefulness of a beautiful environment, the Learning Resources Centre used a two-storey prefabricated steel structure that preserved all the trees and and minimised disturbance to campus activities.
Those trees are now a natural screen protecting the building’s glass facade. The part of the courtyard that remains is connected to a new roof garden, improving campus circulation and the quality of its open space. The adjacent area can also be used for open-air learning in a natural sunlight and tree-shaded setting.
The Hong Kong Society for the Blind Jockey Club Yan Hong Building in Yuen Long was built to help meet the needs of Hong Kong’s growing population of elderly people. The building, with 160 beds, features living space and nursing care facilities designed for the needs of people with visual impairments or other special needs.
The building stands on a triangular site fronting a busy road. Its bathrooms are located facing the road in order to act as a noise barrier. Its south-facing sleeping areas open up to sunlight and pleasant views. A triangular courtyard around these rooms and the adjacent dining/activities space also catches sunshine and summer breezes. All floors are served by four lifts designed to separate clean and dirty activities.
The building’s nurse station is positioned to allow for a view of all the bedrooms. Its floors terrace towards a courtyard where people can do exercise, gardening activities and stimulate their senses. On the main roof is a vegetable garden for residents to enjoy.
The bright colours used on different floors and for window trims aim at reflecting the building’s goal of providing a sustainable and varied way of life for its residents. Smart controls and RFID information systems are installed to assist the visually impaired and other residents with special needs. Overall, the thoughtful planning and orientation of the building protects the residents from noise and other unwanted pollutants providing a hygiene-controlled living environment.
Professor Patrick Lau Sau Shing is a former legislative council member of the HKSAR from 2004-2012, Fellow and Past President of HKIA, Honorary University Fellow of the University of Hong Kong (HKU), Honorary Professor, Former Professor and Head of the Department of Architecture of HKU.
Fig.1 Yan Hong Building front facade detail
Fig.2 Yan Hong Building on On Ning Road, Yuen Long
Fig.3 Plans and section of Yan Hong Building
Fig.4 Sam Tung Uk Museum, serial courtyards
Location: Tsuen Wan
Client: Hong Kong Government
Fig.5 Hong Kong Institute of Vocational Education (Shatin) Learning Resources Centre, big trees in courtyard
Client: Vocational Training Council
Awards: 2008 HKIA Annual Award President’s Prize
Fig.6 HKU SPACE Community College (Kowloon East Campus), connected vertical courtyards
Location: Kowloon Bay
Client: University of Hong Kong
Fig.7 Hong Kong Society for the Blind Jockey Club Yan Hong Building, top: view of south-facing elevation, bottom left: elderly enjoying the courtyard greenery; bottom right: colourful flooring of naturally lit communal spaces
Location: Yuen Long
Client: Hong Kong Society for the Blind
Awards: 2017 HKIA Annual Award, Merit Award, Community Building