Retrofit

Retrofitting Strategy	Application of solar film / heat reduction/ insulated coating at façade / skylight
	Apply special coating on the roof that can irradiate heat from the roof surface to the cold outer space through the atmosphere to reduce the OTTV of the building in order to reduce energy consumption of the air-conditioning system. “Smart” sub-ambient radiative cooling (SSRC) coating/ painting material at external wall and or roof with high solar reflectance index (SRI) can irradiate solar heat. It works by scattering sunlight, converting absorbed UV light to fluorescence emissions and re-emitting infrared radiation to outer space. Keep the interior temperature of buildings at 6°C cooler than the ambient temperature with zero electricity consumption. Reduce the urban heat island effect. Improve air quality by reducing carbon dioxide, nitrogen oxides, sulfur dioxide, and other emissions associated with fossil fuel generated electricity used for air conditioning through the reduction in indoor air temperature. Adding appropriate insulation to external walls can act as a thermal barrier that regulate the building’s internal temperature and can reduce the amount of energy required for space heating and cooling to maintain thermal comfort. Solar radiations to indoor space can be reduced by attaching a solar film on the window, using spray on solar coating or installing reflective solar blind. Energy consumption of the air-conditioning system can be lowered as a result of the reduction in solar load. Although the efficiency of the solar film is less than that of PV, solar film with greener production process. More flexible forms of application, and with different colors. It would be fit for retrofitting.
	Consideration
	Existing concrete wall can be insulated by adding rigid foam boards/ panels at the inner side of the external wall. These added insulation materials to the external wall must be non-combustible for fire safety. If added externally, the insulation would form part of the external cladding system. Life span of the added-on film or coating to the life of the glazing should be considered as to how those can be maintained or replaced. The safety features of the glazing should not be jeopardised. For example, the feature of tempered glass is that it will break into small pieces when damaged either by external force or spontaneous breakage from within. However, if a film is applied, the broken glass is still intact and may fall as a large glass piece, increasing the risk of serious injury to pedestrians.
	Estimated Saving
	QOPAQUE = [AwUwaDT_SOLA,V + ArUraDT_SOLA,H]_PRE – [AwUwaDT_SOLA,V + ArUraDT_SOLA,H]_POST kW_FACADE = 1/COPQFACADEOPHR,yr where Aw, Ar = Opaque wall and roof area Uw, Ur = U-value or opaque wal and roof = 1/[ho+(1/k1+1/k2+…+1/kn)+hi] a = outer surface absorptivity of opaque wall and roof DT_SOLA,V, DT_SOLA,H = sol-air temperature different of wall and roof (orientation) Green roof and green wall would reduce the absorptivity of the opaque wall and roof as well as the sol-air temperature different QPIPE = ApipeUpipea* DT_SOLAPlease click HERE to view the list of terminology.