White roofing – it’s a time-honored concept that’s gained renewed popularity with strong advocates like Energy Secretary Chu and other notables touting its energy saving and climate change benefits. White roofing has been catching on in urban areas; and its execution has occurred largely unfettered by the esoteric language of climate change. Yet, as white roof gains a place in the popular consciousness, more complex criticisms have come to white roof, whether its implementers wanted to talk global climate change or not.
Stanford’s Mark Jacobson and John Ten Hoeve’s recent journal article on urban heat and white roofing has been spawning some eye-catching headlines. Take the shocking, “White roofs are not a global warming silver bullet, study finds.” Climate change solutions rarely make good sound bites. That’s probably why white roofing is so attractive. White paint is simple – easy to implement and easy to grasp.
The Urban Heat Island effect is where the simplicity of white roofing meets complication. The Urban Heat Island causes cities to stay hotter than surrounding suburbs due to a proliferation of heat-trapping surfaces such as roofs and roads. Part of the Stanford report’s intent was to dispute political critics who claim there’s no real climate change beyond the Urban Heat Island effect. If this is true, we can simply cool cities and forget about the rest of human impact on the Earth – a problematic concept for the broad contingent of experts who agree that harmful emissions are the major contributor to climate change. The Stanford report proves exactly what climatologists already knew, that Urban Heat Islands aren’t the end all be all of climate change.
So why bother using white roofs to combat Urban Heat Islands at all? White roofing keeps buildings cooler inside, decreasing the need for summer air-conditioning use. This saves cash-strapped and savvy Americans money while lowering stress on the power grids of big cities such as New York – where black outs and brown outs are summer hallmarks. Lowered energy consumption also reduces harmful emissions caused by the generation of energy. This lynchpin of white roofing is a key point that the Stanford report concedes to ignore. Polemic language aside, white roofing is a money saver, emissions reducer and a good idea for many urban areas. It is one tool in the arsenal of harmful emissions reduction.
Yet, Jacobson and Hoeve dispute a net benefit from white roofs, citing a study finding that on average across the globe, winter heating needs trump summer savings after white roofing.
The study misses a glaring point – white roof isn’t supposed to be modeled all over the globe. White roofing is a targeted strategy that works well in many dense urban areas; it was never recommended for a sort of willy-nilly, throw white coating everywhere implementation plan. White roofing is a net money saver in many cities, as illustrated HERE.
Debate over? Not yet. A final note of caution is delivered in the form of cloud cover. In simplified laymen’s terms, hotter air leads to more sun shielding clouds, meaning that – according to one very preliminary study, which the authors admit requires further research – the ambient air temperature reduction caused by white roofing may not be such a good thing in the aggregate. Jacobson and Hoeve use models that turn all urban roofs and roads white – an unrealistic feat of computerization that over-simplifies white roofing strategy. Again they find that, if implemented on the global scale, white roofing would decrease cloud cover creating a net warming. Another study modeled cloud cover city-by-city, finding cooling benefits in many dense cities, including northern ones.
White roofing does good; there’s no climate change prevention golden goose. White roofing has always been an urban strategy very much concerned with appropriate, benefit-maximizing execution. In the many cities white roof works, it can save 40% on energy bills and make a significant contribution – as part of a broader strategy – to emissions reduction. In dense cities where heat and cost savings matter a lot, this is nothing to scoff at.
Somehow when we fall down the rabbit hole of climate change data, it gets hard to claw our way back out with our sense of practical implementation in tact. The Jacobson and Hoeve study is a smart contribution to the white roof literature. Thankfully scientists, engineers and other modelers have the capacity to test our theories so that we don’t do more harm than good as we attempt to solve difficult problems with complex feedback loops.
When that job is done, it’s the media’s turn to report such findings in a responsible way that expresses all their limitations and caveats and encourages conversation that’s productive, not polemic. There’s plenty of space in our discourse for climate change detractors. Those attempting to find a solution will serve their cause well to remember not to throw the baby out with that bathwater. Targeted success and failure is hardly the same thing.