AN INVESTIGATION OF SURFACE COATING TREATMENTS IN MITIGATING ALGAE GROWTH ON TROPICAL FAçADE SUBSTRATES

Abstract

Buildings in Singapore are susceptible to algae growth due to humidity and the exposure of building façades to year-round sunlight. Gaining a better understanding of how and why algae propagates will allow facility managers in Singapore to make better informed decisions on how to treat algae growth on building façade. Through literature review, five methods of mitigating algae growth on buildings were identified: traditional methods of water jetting, biocides, hydrophobic coatings, hydrophilic coatings and nanomaterial-based biocides. An experimental comparative study was conducted to evaluate the effectiveness of six different coating systems based on the methods identified. The coating systems were tested on a building in Southwest Singapore to simulate real-time environmental conditions on three different substrates. Aluminium, granite and concrete substrates were used in the study because they are typical building façade materials. A digital photogrammetric comparison was then used to derive a quantitative measure of a coating system’s effectiveness in mitigating algae growth in the form of a façade cleaning index. The field results indicated that hydrophilic coatings mitigated algae the best on smoother surfaces, hydrophobic coatings did not perform as well against other coatings from an anti-algae perspective while performance by nanomaterial-based TiO2 was the most consistent across all substrate types. Finally, life cycle cost analysis was conducted and revealed that none of the coating systems had achieved cost savings against the base case of manual water jetting, with the discount rate affecting the cost of the coating systems the most and the façade cleaning index being the second most important variable in affecting decision making.