Page 22 - Climate Control News Magazine August 2019

Indoor Air Quality
A coat to improve comfort, reduce stress
Walls receive less intense sunlight than roofs, but are also less insulated, he explained.
Across most of the US about 40% to 60% of all buildings were built before 1980 when building codes generally specified much less wall insula- tion than required today. As a result, cool-wall savings in these older buildings that meet these older codes could be three to six times greater than those for new buildings, the study found.
“Repainting the exterior walls of pre-1980 build- ings – whether homes or office buildings or stores – with cool paint offers the greatest benefit because they have the least insulation,” Levinson said. “And that’s not difficult to do. There are many light- colored cool paints in local home supply stores.”
While there is not yet a formal, universal defi- nition for cool walls, Levinson suggests that low- er-performance cool walls should reflect at least 40% of solar energy, while higher-performance cool walls should reflect at least 60%. The study assumed that an average wall that is not cool re- flects 25% of sunlight.
Light-colored walls are coolest, but pigments that reflect the invisible half of sunlight and pig- ments that fluoresce can be used to make cool paints in a wide range of colours. Shiny, bare- metal walls are not cool because they are slow to release absorbed heat.
In warm U.S. cities from Miami, Florida, to Al- buquerque, New Mexico researchers found that cool walls could lead to annual heating, ventila- tion, and air conditioning (HVAC) energy cost savings up to 11% for stand-alone retail stores, 8.3% for single-family homes, and 4.6% for medi- um-sized office buildings. And for single-family homes across all California climates, the study found potential energy cost savings of 4% to 27%.
The study accounted for both energy savings in the cooling season and elevated energy costs in the heating season.
The best practice guides are located at BuiltBetter.org
Researchers found cool walls offer comparable reductions in annual emissions of air pollutants such as nitrogen oxides and sulfur dioxide.
AN EASY WAY to cut energy costs and pollution is with a fresh coat of lighter, more reflective paint. Research shows that cool colours also improve
occupant comfort levels and reduce stress.
A study by scientists at the Department of En- ergy’s Lawrence Berkeley National Laboratory (Berkeley Lab) in the United States has found that sunlight-reflecting “cool” exterior walls can save as much or more energy than sunlight-re-
flecting cool roofs.
The researchers found that cool walls offer com-
parable reductions in annual emissions of air pol- lutants such as nitrogen oxides and sulfur dioxide, and greenhouse gases such as carbon dioxide.
Modelling was undertaken on a range of differ- ent homes, retail stores and office buildings in cities
across California and the United States. Lead au- thor, Pablo J. Rosado, said the study featured an analysis of more than 100,000 building simulations.
Berkeley Lab researchers have developed ruby red and Egyptian blue fluorescent cool pigments that could enhance the energy-saving properties of cool wall paints.
Cool walls are generally considered to have a higher-than-average solar reflectance – which means that they reflect a higher fraction of in- coming sunlight than average exterior walls – and high thermal emittance, meaning they can efficiently release absorbed heat.
Berkeley Lab staff scientist, Ronnen Levinson, said cool walls can save as much or more energy than the same size cool roof.
Low carbon best practice guides
KNOWLEDGE OF LOW carbon best practice for a home and building’s lifecycle – construc- tion, retrofit and operation – is now available via the CRC for Low Carbon Living’s (CRCLCL) Low Carbon Guides.
These user-friendly guides will help consum- ers and professionals make informed decisions about their home, commercial property or devel- opment project – from understanding an elec- tricity bill to creating a sustainable precinct.
The guide series is housed on the CRCLCL’s research legacy portal BuiltBetter.org which also includes all reports, conference papers, journal articles and fact sheets produced over its seven year lifespan.
There is even practical guidance for built en- vironment professionals and regulatory agen-
cies seeking to optimise development projects to moderate urban microclimates and mitigate urban heat island effects in major urban cen- tres across a range of climates in Australia. Rec- ognising the need to address carbon emissions from existing residential buildings, the portal includes a guide to low carbon residential build- ings (retrofit).
Historically, policy on reducing carbon emis- sions has focused on regulating new-build pro- jects; however, with less than 2% of the building stock in Australia replaced each year, there is a clear need to reduce carbon emissions in homes that have already been built and occupied.
The document builds on key research conduct- ed nationally in the areas of low carbon retrofit options, housing typology and climate.
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