1. 1 Product development for green productivity a case study Development of algae resistant surface coating for building facades in the humid tropics 2 nd APO World Conference on GP Manila 9-12 Dec 2002 LOH Wah Sing Institute of High Performance Computing Singapore

2. 2 Outline of presentation Paint failure on painted building facades with respect to microbial fouling – site survey - pattern of fouling - algae vs. fungus Causes of paint failure Climate of tropics vs. sub-tropics New paint quality attributes + environmental consideration Screening of algal resistance in field Full field test New product standardisation Implication of project to green productivity

3. 3 About Singapore Urban island nation near the equator Area : 660 sq km Population : 4 million; 6000 people/sq km 860,000 public apartments (Ave 70 sqm/unit) housing 3 million population Mass construction of public housing by Housing and Development Board started from early 1960s

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5. 5 General microbial fouling on building facades

6. 6 Finishing on building facades Paint finish widely used on residential buildings Problem of unsightly disfigurement of paint by microbial fouling became serious from 1970s Microbial fouling on facades was caused by algae, not by fungus – latter advocated by paint manufacturers Main fouling algal species : Trentepohlia odorata Conventional emulsion paint short lived – 3 yrs Frequent repainting caused social disruption for urban living HDB tried solvent-based paint for repainting fobs from early 1980s – emission of 900 tons of solvent per year

7. 7 Fouling on porous surface (right)

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9. 9 Microbial growth along cracks

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12. 12 Algae - Growth on both inorganic and organic substrate - Photosynthesis capability, presence of chlorophyll Fungus - Live on organic substrate as source of food

13. 13 Causes of paint failure Climatic stress – temperature, humidity, rainfall, UV radiation Detailing of buildings – consider tropical features? Quality of substrate – porosity Quality of paint Painting specification Painting workmanship

14. 14 Climate - Singapore vs. Miami Singapore: 103 o E, 1 o N Miami :80 o W, 26 o N Temperature, o CMinimumMaximumMean 1 Q S’pore233126 Miami142620 2 Q S’pore243127 Miami213225 3 Q S’pore243127 Miami243428 4 Q S’pore243026 Miami182823

15. 15 Climate - Singapore vs. Miami Singapore: 103 o E, 1 o N Miami :80 o W, 26 o N Humidity, %MinimumMaximumMean 1 Q S’pore639684 Miami559575 2 Q S’pore649784 Miami529272 3 Q S’pore649683 Miami559073 4 Q S’pore669786 Miami579476

16. 16 Climate - Singapore vs. Miami Singapore: 103 o E, 1 o N Miami :80 o W, 26 o N Rainfall, mmSingaporeMiami 1 Q599289 2 Q529605 3 Q513767 4 Q732376 Total2,3732,037

17. 17 Climate – solar radiation A Davis & D Sims, “Weathering of polymers” (1983), Applied Science Publishers L.R. Koller, “Ultraviolet radiation”(1965), Wiley  Total solar radiation shows maximum intensity at latitude 15 deg  Solar UV radiation shows * max intensity at equator, decreases with increasing latitude * max intensity at noon of day * max intensity in summer of year  Combination of UV and moisture (humidity) accelerates degradation (S.P. Pappas, “Weathering of coatings – formulation and evaluation” (1989), Prog in Organic Coatings, vol 17, No.2, pg89)

18. 18 Product development – attributes considered Cost effectiveness Service life of 6 years or more under humid tropical climate Environmental consideration – water-based paint to be developed Rule 66, smog, VOCs, fire & health hazards etc Formulation for weather durability – binder/pigment ratio, type of binder, biocides, additives * High pigmentation level causes chalking/erosion * Binder susceptible to moisture and alkali will not last * Hygroscopic additives will affect moisture sensitivity of paint * Low pigmentation characterised by appearance of sheen on dry paint surface

19. 19 Weathering test – crack- present and crack-free quality

20. 20 Screening test against algal resistance at field

21. 21 Screening against algal resistance at field

22. 22 Field test on 8 buildings for 8 yrs; Example – Changi Telecoms Building

23. 23 Field test – algal growth on glass window due to condensation

24. 24 Product standardisation – for purchasing specification S.S. 345 1990 S.S. 150 1976 Gloss, 85 deg15 – 50Max 20 AppearanceSheenMatt Wet scrub resistance, No. cycles passed 3,0001,500 Accelerated weathering, hours 1,000500 Algal resistancePass testNR Fungal resistanceNRPass test NR: not required

25. 25 Life cycle costing Tender optionABB/A No. blocks for repainting455 Types of paintS.S. 150S.S 345 Total tender priceS$29.2mS$38.2m1.3 Warranty period3 years6 years2.0 Expected service life of paintwork 4 years7 years1.75

26. 26 Impacts and benefits Product commercialisation * 11(14) paint manufacturers in S’pore * Adopted in Brunei and Hong Kong Changing marketing concept of paint * Partnership of paint manufacturers and painters * Sell paint (semi-product)  sell paintwork (finished product) Cost effectiveness * Extended service life  longer repainting cycle * Life cycle costing  savings of S$2 million/year Green productivity * Waste reduction  savings of labour (paint production and painting), scaffolding, water, paint materials, logistics and administration…. * VOCs elimination  savings of 900 tons solvent/year * Reduced ESH impact

27. 27 Thank you