It Isn’t Easy Grading Green
Nations have their own shade of green embodied in their rating systems, and differences can reveal new approaches to the very concept of sustainability.
Green-building certification systems have been around for 20 years, but new ones are still emerging all over the world. They differ from each other because of cultural and climatic variations, but all share the common goal, broadly defined, of sustainability. Granddaddy of them all is the British Building Research Establishment Environmental Assessment Method (BREEAM), introduced in 1990.
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All these systems, according to the U.S. Green Building Council senior vice-president Scot Horst, “address a lot of the same ideas: site issues, water, energy, materials, and indoor environmental quality.” Horst works with the Paris-based Sustainable Building Alliance (SBA), which brings the USGBC together with other nations’ green-building organizations to develop common metrics. “We’re finding ways we can be sure we’re measuring things the same way across different rating systems,” Horst explains. “If you’re going to measure carbon in BREEAM, for instance, we’ll do it the same way in LEED. This will send a more consistent message to the industry.” Importantly, this is not the same as trying to devise a universally applicable rating system.
Worldwide, systems have many differences, large and small, and a building evaluated by one may fare differently if evaluated by another. According to a rough comparison conducted by the BREEAM Centre, buildings that score “Platinum” on the USGBC’s LEED system would only score BREEAM’s second-highest score (“Very Good”). Buildings that rate high marks on a green assessment generally exceed the standard building codes in their home country. So nations in Europe, for instance, which have stricter standard codes than the U.S., will also tend to have more rigorous green assessment criteria.
Europe has also embraced life cycle analysis (LCA) to a greater degree than has North America. Joel Ann Todd, an independent consultant and chair of the LEED Steering Committee, notes that the Environmental Product Declaration (EPD) system, which provides LCA data, is standard in Europe. “This has made it possible for them to include LCA for a long time,” she says. “It hasn’t happened in the U.S. because we’re just starting to get the data. In Europe where they have good data, it’s widespread.”
Another major difference between the world’s systems is the weight they give to different categories. For instance, Japan’s Comprehensive Assessment System for Building Environmental Efficiency (CASBEE) gives land use a 2 to 3 times greater fraction of the total score than systems in Western countries. Another example is Australia’s Green Star system, which is built on BREEAM and LEED, but modified for hot climates. It uses a credit system with nine categories, some of which—indoor-air quality, water, materials, land use, transport, and innovation—are similar to LEED categories. Green Star also offers credit specifically for reducing greenhouse gas emissions and for adopting sustainable development principles from project conception through construction and operation. Like LEED’s design and construction rating systems, Green Star predicts the environmental performance of buildings before they are occupied. Green Star doesn’t have its own version of LEED’s Existing Buildings, Operations & Maintenance (EBOM), but it is complemented by the National Australian Built Environment Rating System (NABERS), which measures actual performance.
New Zealand and South Africa have recently adopted the Green Star system. Similarly, The Netherlands and Hong Kong have based their own systems on BREEAM. And LEED has been adopted in Brazil, Canada, and Italy. Indeed, LEED is used internationally, by multinational corporations for instance, that build in many countries and want to have a common system for their entire portfolio. Over the years, many researchers have tried to calculate comparisons between various systems. But differences of weighting, culture, and climate have given these comparisons an aura of apples and oranges. Thomas Saunders, who conducted one such comparison for the BREEAM Centre, concluded that “none of these systems travel well if used in countries other than those the system was initially designed to work in. It therefore suggests that outside the native country, systems should be tailored to account for context.”
In the absence of its own system, China has been using LEED, but in 2007 the Chinese Ministry of Housing and Urban-Rural Development (MOHURD) launched Three Star, an official green-building evaluation standard. It consists of six categories—land, energy, water, resource, environment, and operations—and a building is rated as One-, Two-, or Three-Star based on the minimum score of each component, rather than the total. Buildings are rated after one year of occupancy. The national government is in the process of establishing provincial capacity to implement guidelines and modify them for regions. Recognizing the trade-offs between some guidelines, such as increasing the amount of material to make a shell more energy-conserving, Three Star encourages a life-cycle view of optimizing overall sustainability. According to consultant Gunnar Hubbard, principal of Fore Solutions, who has studied the Chinese system, Three Star diverges from LEED in many ways. As examples: it gives credit for reducing noise pollution, avoiding pipe leakage, ensuring airtight windows, setting thresholds for harmful substances, and establishing a maximum air temperature in naturally ventilated spaces. In contrast, LEED does not give credits for compliance with standard building regulations.
Most systems worldwide are structured like LEED: points are earned in the various categories, and a rating is given based on the total. LEED is different from most other systems though, in that it allows architects to select which criteria they will measure. If a building is weak in one, it doesn’t earn that point, but is not otherwise penalized. In contrast, says Todd, “in most other countries, they score against all the criteria, so you see the categories where the building is not performing as well.” The USGBC rejected that approach, hoping to incentivize owners and designers. Todd adds, “No one is really excited about a scorecard that says you did great here but not there.”
Of all the rating systems that are brutally comprehensive in evaluating every category, Japan’s stands out because of its unique structure—both rigorous in evaluation and explicit in portraying the balance between positive and negative impacts of a building. Japan’s CASBEE was designed to integrate two longstanding construction industry goals: maximizing occupant well-being and reducing environmental impacts. CASBEE draws a hypothetical boundary around a building and its immediate site. Within that boundary, the goal is to maximize the quality (Q) of occupant benefits. Outside the boundary, the goal is to minimize the negative loads (L) on the environment. “L” takes into consideration factors such as energy efficiency, recycled materials, and pollution reduction. “Q” measures, for example, acoustic and lighting comfort, durability and adaptability of interior components, and outdoor amenities. The ratio of Q/L is calculated as the Building Environmental Efficiency (BEE). A high BEE indicates more positive than negative points. This score, when plotted on a graph of L by Q, dramatically shows the performance of a building in comparison to less sustainable buildings. The graph displays areas of poor to excellent performance, roughly equivalent to LEED’s spectrum of uncertified to platinum, but the way CASBEE structures its score makes direct comparisons to LEED very difficult. CASBEE’s four primary assessment tools are for predesign, new construction, existing buildings, and renovation. There are also special-purpose tools for temporary facilities and detached houses and to evaluate urban-heat islands.
Sustainable design is not limited to the industrialized nations. Indeed, certification work in developing countries has produced interesting results and a broader definition of sustainability. Jeremy Gibberd, of the Council for Scientific and Industrial Research (CSIR) in South Africa describes the Sustainable Building Assessment Tool (SBAT). In developing countries, he argues, it makes no sense to evaluate green buildings independently of the sustainability of the surrounding society. Greenness pales in importance when the local economic, health, and educational systems are in disarray. SBAT was designed to be widely inclusive by considering these systems and involving the local community in implementing the sustainability guidelines. Buildings are evaluated by the degree to which they support the broader goals. The evaluation tool includes 15 objectives in three categories: social sustainability (occupant comfort, inclusivity, access to facilities, participation/control, education/health/safety); economic sustainability (local economy, efficiency of use, adaptability, ongoing costs, capital costs); and environmental sustainability (water, energy, waste, site). CSIR is currently implementing the SBAT in pilot projects.
Although the German construction industry is no stranger to energy efficiency, it is only in the past few years that the German Sustainability Building Council (DGNB) has come out with its Sustainable Building Certificate. It is a voluntary system built around the six categories of ecology, economy, socio-cultural and functional topics, technical quality, processes, and location. Built around local codes and norms, it evaluates the overall performance and life cycle of a building rather than individual measures. Other European Union nations, including France, Italy, The Netherlands, and Spain, are also developing their own standards. The European Union’s Energy Performance of Buildings Directive requires all buildings to be labeled with their energy consumption. This provides information to tenants and owners and sends an unquestionable message to industry.
According to engineer Jerry Yudelson, president of Yudelson Associates and author of Green Building Trends: Europe, the United States is ten years behind Europe in sustainable design. He recommends that U.S. building codes be upgraded to incorporate LEED objectives. This idea has been boosted by the recent launch of the International Code Council’s International Green Construction Code, which aims for carbon neutrality by 2030. Presumably, toughening mandatory codes will also step up the rigor of a voluntary rating system. Reviewing other systems around the world can reveal further options for tightening standards, rethinking the assessment calculation, and broadening the very concept of sustainability.