By 2100 it may be impossible for humans to work outside. If the world continues on its business-as-usual growth trajectory, global temperatures could rise beyond 95 degrees Fahrenheit – the highest tolerable “wet bulb temperature” – as the new norm in many parts of the world. Particularly in urban areas, where heat island effects can add up to 10 degrees Fahrenheit, temperatures would be especially unbearable.
How do we avoid such a bleak future? On June 19, Diana Ürge-Vorsatz – coordinating lead author of the buildings chapter of the IPCC’s 5th Assessment Report on Climate Change Mitigation – shared her thoughts here at Yale on the potential to counter climate change through building efficiency.
The map in the top right-hand corner shows the BAU greenhouse gas emissions scenario, also known as RCP 8.5 in the scientific community.
Passive House Standard
Ürge-Vorsatz made the case, based on emissions data, that the most cost-effective way to mitigate climate change is through building efficiency improvements, compared to emissions reductions in other sectors. In particular, she highlighted one building concept – the passive house – that not only can guide reductions in our carbon footprint but also help us “weather the weather.”
The Passive House Standard, launched in Germany, specifically targets energy efficiency (in contrast to holistic standards like LEED). Employing high-quality insulation and ventilation, passive houses require incredibly little energy for space heating and cooling. Case studies show that passive houses reduce energy consumption by much as 80 to 90 percent compared to typical buildings in central Europe. The buildings themselves can be residential or nonresidential, new or retrofits, and are relatively low-cost over their lifetime, although they do require additional upfront costs for the design and higher-quality building components. Ürge-Vorsatz’s research conservatively estimates that if all current building stock were to achieve passive-house levels of energy reduction, world energy consumption would fall by 30 percent. These energy reductions could help us avoid the 2100 BAU scenario, though they would obviously need to happen sooner than later.
While it’s been proven that passive houses require very little energy to regulate temperature, can this technology be scaled? How well do passive houses perform outside of Central Europe, their temperate birthplace, particularly in more extreme climates? The airtight insulation of passive houses apparently excels in retaining warmth in cold climates, most prominently in Iceland where rough forms of the passive house date back to the Middle Ages. However, it was argued during the talk’s Q&A that while the concept is less adept at providing cooling in hot, humid climates. If this is true, how would passive houses fare in a country like India, which suffered its worst heat wave in over 60 years this summer?
Intrigued, we researched what work has been done to pilot passive houses in hot climates. A 2013 study by the Passive House Institute says passive house design can thrive in tropical climates (Jakarta, anyone?) if adjusted to include features such as interior insulation, solar control glazing, fixed window shades, and ventilation with heat and energy recovery.
Of course, it would help to know how much warm-climate adjustments would cost – particularly in developing countries where upfront costs may already be higher due to the relatively limited number of manufacturers that are versed in passive building components. To the extent that the passive house concept is flexible, countries can adapt it using their own design techniques.
Another area for exploration concerns air quality. Although passive houses should have good air quality by design and be made of non-toxic materials, any cutting of corners (e.g., substituting cheap toxic materials) could prove troublesome given the extreme insulation.
A global map of where passive houses are currently located is available here.
Living Building Challenge
Another green building concept, the Living Building Challenge (LBC) was presented on last week by the Connecticut Collaborative. LBC is the most stringent and holistic of green building certifications, surpassing both LEED and Passive House Standard in their approaches to efficiency.
The Living Building Challenge (LBC) incorporates criteria that are non-traditional metrics of green buildings, including considerations of equity, human health and happiness, and beauty. While LEED-certified buildings can still have negative environmental impacts, living buildings must provide real environmental benefits. For example, they must be net energy and water positive, and cannot use combustion-based energy sources.
While the LBC philosophy and movement are inspirational, it is hard not to recognize the uphill battle living buildings face in achieving commercial adoption. Currently, there are only five certified living buildings in the whole world. Building them can be cost-prohibitive, especially when current financial models for buildings don’t account for healthcare cost reductions, and increased productivity.
Getting retro right
Independently, the Passive House Standard and Living Building Challenge present two promising solutions to avoid the “lock-in” scenario Ürge-Vorsatz described. She stressed that shallow retrofits – anything resulting in less than 80 percent in energy reduction – are harmful, as they risk locking buildings into a path-dependent scenario of sub-optimal performance. Since both standards have stringent energy reduction requirements, they represent potential standards that could be scaled up and prevent the future nightmare BAU scenario of 2100.
If you want to get more involved with the Living Building Challenge, like “Living Building Challenge Connecticut Collaborative” on Facebook and check out the International Living Future Institute website where you can sign up to be an ambassador.
Austrian Embassy in Jakarta, Indonesia. Credit: Timothy/Austrian Embassy Jakarta.
Omega Center for Sustainable Living in Rhinebeck, New York. Credit: Farsid Assassi/BNIM Architects.