High-Performance Green Buildings
It pays to go green with new construction. According to the US Green Building Council (USGBC), green buildings cost no more to build—and sometimes less—when project teams take an integrated design approach that considers sustainability goals throughout the whole building lifecycle.
Consider the example of a green office complex for environmental nonprofits in Berkeley, California. Located just one kilometer from a fault zone that is predicted to produce major earthquakes, the David Brower Center met ambitious sustainability and seismic performance goals thanks to collaboration among the architect, engineer, developer, and contractor.
“The key was integrating these goals into the selection of structural systems, materials, and assemblies that responded to both the seismic design and sustainability of the project,” explained Tipping Mar Associate Leo Panian, structural design team member. “Rather than treat each of these goals independently, we exploited opportunities where possible to develop common solutions—recognizing the imperative to maintain the cost effectiveness of the structure.”
Sustainable design principles have been in practice for some time, but building owner/operators are seeking validation of their investments through certification programs such as the USGBC’s Leadership in Energy and Environmental Design (LEED) Green Building Rating System; the Green Building Initiative’s Green Globes rating system; and the Building Research Establishment’s Environmental Assessment Method (BREEAM). In fact, there are so many rating systems that the General Services Administration’s new Office of Federal High-Performance Green Buildings has adopted the evaluation of credible green building rating systems as part of its mission—with the goal of disseminating best practices from each.
Perhaps the best known worldwide, the LEED rating system allows builders the flexibility to earn points in six categories, in which the total number of points determine the certification level. The David Brower Center, for example, targeted LEED-Platinum certification, which is the highest of the four progressive levels and requires 80 points or more. According USGBC Senior Vice President Scot Horst, LEED certification verifies that a building designed to a LEED standard has actually achieved that goal. “As an owner, you know you got what you paid for,” he said.
The green premium
With cost control as a major concern today, it seems counter-intuitive to program green goals into new construction projects. But going green can be a cost-saving measure. In the United States, more than 18 Federal agencies have adopted guidelines for designing high-performance, sustainable buildings as a way to reduce the total cost of ownership. These guiding principles, developed by the US Environmental Protection Agency (EPA), call for using integrated design, optimizing energy performance, protecting and conserving water, enhancing indoor environmental quality, and reducing the environmental impact of materials.
Several states have similar initiatives. In Pennsylvania, the Governor’s Green Government Council instructed all 27 state agencies to follow its “Guidelines for Creating High-Performance Green Buildings.” The Council made the business case for green buildings this way:
“The return on the investment made in sustainable design is manifest in reduced operating costs, occupant satisfaction, reduced absenteeism, and increased performance. These attributes, in turn, translate into more marketable buildings and a robust real estate industry. Creating buildings that are flexible, adaptable, and responsive to changing technology enhances the vitality and longevity of our building stock.”
Sustainable design pays off in large part through energy efficiency. The US EPA reported that a 30 percent reduction in building energy use can yield the equivalent of a 5 percent increase in net operating income and overall asset value. The agency certifies energy efficiency through the ENERGY STAR Program. Kohl’s Department Stores, for example, operates 219 ENERGY STAR-labeled stores, which feature centralized energy management systems; occupancy sensor lighting; and high-efficiency lighting, heating, and cooling systems.
The family-focused retailer also built a LEED-Silver certified store as the prototype for future construction. “Operating practices that are good for the environment are also good for business, our customers, and our associates,” said Ken Bonning, Kohl’s executive vice president of store planning and logistics. “Through environmentally responsible practices and initiatives, such as energy management and green building design, we reduce operating costs and create a comfortable shopping and work environment.”
There is no underestimating the public relations value of high-performance green buildings, but experts caution against headline-grabbing features that may be less cost effective than more subtle measures. An integrated design approach enables project teams to select green strategies in the context of whole building performance.
Bentley’s Building Performance Group provides solutions for the rigorous building analysis and simulation necessary to achieve the high performance standards set by USGBC and others. “This group offers a growing number of highly integrated, advanced software tools that architects, engineers, and low-carbon consultants can deploy to address the increasing demand for buildings designed with lifecycle performance in mind,” noted Bentley CEO Greg Bentley.
When LEED certification is a design goal, project teams can weigh the relative merits of various strategies for earning points for Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, Indoor Environmental Quality, and Innovation in Design. This process produces projects that “cost less to operate and maintain, are energy- and water-efficient, have higher lease-up rates than conventional buildings in their markets, and contribute to occupant health and productivity,” according to USGBC.
Not surprisingly, green buildings are built to last, so any green premium paid up front is an investment that is repaid over the long life of the building. As Panian said of the sustainable design for the David Brower Center, “It can be abstracted as an amortized yearly probability of financial loss due to earthquake activity. More simply, it’s about not making disposable structures.”
Extreme Green Center for Environmental Advocacy
Located just one kilometer from the Hayward Fault, the David Brower Center in Berkeley, Calif., is designed to withstand an inevitable 7.0 magnitude earthquake—epitomizing the meaning of sustainable. The $74 million mixed-use building reflects the city’s commitment to environmental stewardship. With a LEED-Platinum rating pending from the US Green Building Council, the center provides offices for nonprofit environmental organizations, while Oxford Plaza Housing provides 97 affordable housing units.
For the structural engineers, the overarching goal was to protect the building and the energy embodied in its various components by controlling and limiting damage from a large earthquake. “This is what I term deep sustainability, in contrast to the more active aspects of architectural and mechanical design that deal with energy consumption, water use, and indoor air quality,” explained Leo Panian, associate at Tipping Mar, a firm known for innovation in seismic-resistant design. “LEED-Platinum would seem a rather hollow designation if the building were to be totaled by the next big earthquake.”
Concrete was selected as the building material of choice. To minimize the environmental impact of CO2 emissions from cement production, blast furnace slag was substituted for as much as 70 percent of the cement in the concrete mixes. Tipping Mar Associate Mark Stevenson added, “Bentley’s RAM Concept provided a powerful multipurpose tool for design of the concrete elements, from design of the mat slab to analysis of both mild and post-tensioned elevated slabs.”
The project team conceived a structural system that uses a combination of post-tensioned walls and frames capable of not only minimizing earthquake deformations, but also restoring the building to its original geometry following a major earthquake. The structure was designed for basic code seismic criteria, so the owner did not incur a cost premium. The design also incorporated conventional construction methods and materials, not relying on high-tech devices such as viscous dampers or seismic isolators.
Three dimensional structural models were used to verify the design and predict seismic response. Real-time dynamic ground motion simulations enabled the engineers to assess with accuracy and precision the expected deformations of the structure and obtain a high level of confidence about the design solution, which fulfilled the goals of efficient resource use, reduced embodied energy, and reduced lifecycle costs.
What It Means To Be Green
The green community has identified these common characteristics of green buildings:
• Integrated Design
Considers the whole building throughout its lifecycle
• Energy Efficiency
Reduces fossil fuel consumption and carbon emissions
• Water Conservation
Manages water use/reuse indoors and outside
• Low-Impact Materials
Minimizes lifecycle environmental impacts
• Community Connection
Preserves the cultural and natural character of the region
• Sustainable Land Use
Protects the ecosystem, watershed, and wildlife habitat
• Climate Adaptation
Uses passive design responsive to weather conditions
• Daylight and Fresh Air
Creates a clean, comfortable indoor environment
• Optimal O&M
Reduces lifecycle operation and maintenance costs
• Long Life
Creates flexible space suitable for adaptive reuse
Sources: American Institute of Architects Committee on the Environment, National Institute of Building Sciences, US Environmental Protection Agency, US Green Building Council
Article courtesy: Bentley Systems, Incorporated