by Chris Fisher
February 1, 2008
According to the 2005 ARB Architectural Coatings Survey, the VOC emissions from architectural coatings dropped from 113 million tons per day in 1975 to 95.1 million tons in 2004, a 16% drop in emissions.
Energy-Efficient Paints Can Reduce Urban Heat Islands, Smog and Greenhouse Gases
Heat-reflective wall coatings can also reduce stress on a home by minimizing the expansion and contraction of the home’s exterior walls, which occurs during intense fluctuations in temperature. It is a well-documented fact that heat-reflective coatings on flat roofs can substantially reduce utility bills depending on insulation, geography, sun orientation and other variables. This is why commercial cool-roof coatings are part of the California Energy Commission’s (CEC) Title 24 energy code. In 2008, the CEC is expected to include heat-reflective residential cool roofs as part of the state energy code. The next step in thermal envelope legislation could be energy-efficient wall coatings.
Promoting the energy-saving benefits of heat-reflective wall coatings is Ferro Corporation Development Manager for Pigment Systems, Ken Loye, and Ferro Corporation, West Coast District Manager, Jimm Dunn. “In many instances we see more heat penetrating through walls than through roofs, especially in the downtown areas of big cities,” said Dunn. “We think reflextive walls would benefit many industry segments.”
Former Rohm and Haas chemist and Cool Roof Rating Council (CRRC) Technical Chairman, Bill Kirn, wrote a report called, Cool Roof Coatings to Reduse Energy Demand and Temperature in an Urban Environment. In that report, Kirn concluded that once a roof had been coated with a white, reflective membrane then it was no longer the principle source of solar heat. Exterior walls were now the leading contributor of heat ingress.
Impact on the Consumer
Most paint companies that sell green coatings promote low VOCs, which is a good feature but does nothing to impact the consumer in a monetary or environmental manner. Low-VOC coatings sold at retail level are not energy-efficient, do not lower radiant heat transfer or monthly utility bills. At a recommended DFT of 1.4 – 1.8 mils in two coats, there are more repaint cycles and, therefore, more VOCs in the atmonsphere. Every time a home is repainted there is additional energy consumption, resources and labor costs. Left over paint ends up contaminating landfills and water streams. Extra gas and electricity are used to drive trucks, operate pressure cleaners, run spray rigs and blend coatings. By repeatedly coating walls, there is a negative effect on the environment. It makes little sense specifying low-VOC coatings with low-film builds if walls have to be frequently recoated.
Paint manufacturers need to see the huge benefits of producing energy-efficient coatings from both an environmental and financial standpoint. Consumers benefit from lower utility bills and fewer paint cycles, and the environment benefits by lower greenhouse emissions. According to the head of the Heat Islands Research Project at LBNL, Ph. d. scientist Hashem Akbari, estimates that for every 1kWh of electricity saved, approximately 663 g of CO2 is also saved. Just imagine the enormous savings in CO2 emissions if millions of U.S. homes were coated with heat-reflective paint.