TOWARDS A BREATHABLE CITY: A STUDY ON RETROFITTING TITANIUM DIOXIDE AND GREEN WALL AS AIR PURIFICATION STRATEGIES ON RESIDENTIAL BUILDING FACADES IN SINGAPORE

Abstract

Air pollution has become a bane for millions of city dwellers; it poses a mounting risk to the health of the young and very old, pregnant women and people with heart and respiratory conditions. Given that it is hard for air pollution emission to be entirely prevented at the source, strategies for localised atmospheric cleansing are also important to ensure the local environment is cleaned of air pollutants.

This paper identifies the major air pollutants in Singapore and how polluted air in buildings can be mitigated with architecture. Focusing on naturally ventilated interiors, it is proposed that a combination of air purification systems that require minimal maintenance and energy input during operation be retrofitted into existing buildings to provide clean air for the building occupants. These systems are hypothesised to be best placed on the building facades in order to clean the air before it enters the building.

The chosen systems, titanium dioxide-coated panels and green walls, are chosen as complementary, climate-responsive systems that harness natural forces such as sunlight, rain and winds to effectively clean the air of pollutants. As these systems are located on the building envelope, their air purifying functions can also be designed to improve other aspects of indoor environment quality, such as amount of daylighting, ventilation and indoor temperature. Kent Vale Residence, which consists of high-rise residential apartments, is chosen for retrofitting study. It is proposed that the air purification strategies used in Kent Vale are can be adapted into typical high-rise residential buildings in Singapore.

As there are limits to the quantity of air purification features that can be placed outside a fenestration without adversely affecting indoor daylighting and ventilation, it is recommended to supplement the outdoor air purification methods with indoor methods. Lastly, further research should be done on designing air purification strategies which complement and perform effectively together, and testing the viability of outdoor air purification strategies in outdoor conditions.