Green Star, LEED, and Passive House U.S. standards are undergoing – or have recently undergone – substantial revisions and are racking up more evidence of their efficacy.
The Green Star – Design & As Built rating tool draft credits, for example, were recently released by the Green Building Council of Australia for industry and public comment. According to GBCA chief executive Romilly Madew, the draft credits are a major milestone in the evolution of the Green Star program.
A major goal for this revision, Madew explained, was to “reduce the cost of compliance and certification and encourage innovation and world leadership in the delivery of buildings that are more sustainable and better for people too.”
Some credits may be removed, which would streamline the process, and emerging issues may be covered with new or revised credits. The credits affected include:
- Adaptation and Resilience
- Sustainability Impacts from Transport
- Reduction of Construction and Demolition Waste
- Material Life Cycle Impacts
- Responsible Sourcing of Construction Materials
- Product Transparency and Sustainability
- Sustainable Sites; and,
- Heat Island Effect Reduction.
In the 12 years since it came about, the GBCA has certified more than 640 projects, and has evidence that its standards have improved performance. Compared to an average Australian building, Madew noted, Green Star-certified buildings cut greenhouse gas emissions 62 per cent, electricity use by 66 per cent, and water use by 51 per cent.
The US Green Building Council’s LEED rating system underwent an overhaul in 2013 and has faced challenges from competitive standards, as well as attacks from state governments. Nonetheless, LEED can point to evidence that, despite its flaws, it delivers better buildings with lower life-cycle costs.
A 2009 study, Life Cycle Cost Analysis of Occupant Well-Being and Productivity in LEED Offices by Michigan State University student Amanjeet Singh and Michigan State professor Dr. M.G. “Matt” Syal, CPC, LEED AP, analyzed 30 completed LEED projects and noted, “life cycle benefits far exceed the incremental costs, indicating economically viable investments.”
The USGBC’s article, The Business Case for Green Building, cites numerous studies linking green buildings with improved financial metrics. According to the study, “upfront investment of 2% in green building design, on average, results in life cycle savings of 20% of the total construction costs – more than ten times the initial investment.”
Owners of green projects, meanwhile, reported a 19.2 per cent improvement on ROI for existing green building projects and 9.9 per cent for new green building projects. Operating costs dropped by 13.6 per cent on new builds and 8.5 per cent on existing projects.
With about 100 projects certified in North America, the European Passive House standard has been tried in just about all climates, and the verdict is clear: the European standard does not work everywhere. The climate in central Europe is milder or less extreme than many areas in North America, leading to a host of challenges in meeting a standard optimized for that climate.
With that in mind, the Passive House Institute US (PHIUS) Technical Committee has been working since 2011 to modify the standards for all climate zones in North America. Passive House Institute US was established in 2007 and is the certifying agency in the US.
In cold climates, the annual heat requirement of roughly 15 kilowatt/hours per square metre per year has led builders and architects to overinsulate and overglaze beyond their cost effectiveness. In warmer climates like California, the 15 kWh standard is actually too high, meaning that even more cost-effective energy savings could be achieved. In hot and humid climates like Florida, cooling loads demand more than the standard permits; it’s unattainable.
PHIUS co-founder and executive director Katrin Klingenberg wrote in a blog post that the Technical Committee settled on four principles to guide the development of the new standard:
“1. Being biased towards conservation by constraining the envelope design through definition of annual heating and cooling demands and peak loads per climate that must be met using passive measures first. The climate-specific annual demand thresholds should pay back the investment and peak load thresholds should assure comfort. 2. Meeting a total primary energy maximum per person for all energy uses in a building. This is essentially the equivalent to a carbon limit, responding very directly to the amount of carbon savings that need to be achieved in the building sector to stabilize the climate. 3. An airtightness requirement assuring building envelope durability, verified by climate and measured in air leakage per square foot of envelope area. 4. Cost-effectiveness using national average costs for materials and energy.”
PHIUS is working with Building Science Corporation to “define passive standards by climate zone according to U.S. cost data.”
The complex testing and calculations use the energy modeling tool WUFI Passive and energy- and cost-optimization tool BEopt. The group’s findings are scheduled to be released at the Ninth Annual North American Passive House Conference in San Francisco September 12–13.