Different climate zones require different design strategies
Different climate zones require different design strategies.
When the common man imagines a building, he likely pictures a four-sided brick box. But the energy-minded owner and architect have to think outside that construction.
To maximize the effectiveness of the facade, it is likely that no side of it will look the same. Different climate zones require different design strategies, and those strategies entail taking a unique approach to the building’s orientation. Special treatment should be given to each aspect of the system.
The U.S. is divided into eight climate zones, and each can be generally described as either hot, cold, or mixed. From there, classifications splinter into three sub-zones: humid, dry, or mixed. General principles pertain to each categorization, but it’s recommended to consider each city’s specific climate data before taking on a project, says Ajla Aksamija, assistant professor of architecture and design at University of Massachusetts Amherst and author of Sustainable Facades: Design Methods for High-Performance Building Envelopes.
“For hot climates, you need to protect the building from sunshine, reduce solar heat gain, provide shading, and orient it so that you’re not maximizing east and west exposure, but instead north and south,” she explains. “Everyone wants to maximize daylight, and that can be challenging while minimizing heat transfer with shading. Skylights and light shelves can be effective.”
In cold climates, some of the same general principles apply. Buildings in cold regions should also minimize east and west exposure while maximizing north and south. But heat transfer is mitigated from the inside to the outside with increased building mass and insulation levels, Aksamija explains.
For mixed climates throughout the Midwest and into some areas of the Northeast and Northwest, it’s best to take a balanced and nuanced approach.
“Analyze each facade orientation and look into specific climate data to differentiate each season,” says Aksamija. “Improving thermal resistance will be important in any climate, but in mixed climate there is also a desire to increase daylight and utilize shading.”
At the Center for Urban Waters in Tacoma, WA, no two sides look the same (see Case Study #1).
“The project’s orientation wasn’t ideal,” notes Aksamija. “Treating each wall differently resulted in success. You have to figure out unique strategies.”
The University of Texas at Dallas Student Services Building in Richardson, TX, has similar strategies on three sides of its structure, yet it’s also achieving success (see Case Study #2).
Case Study #1
Photo Credit: benjamin benschneider / otto
Center for Urban Waters
Building Description: Located in a mixed climate, this 51,000-square-foot facility is a research laboratory that also includes office space. Certified LEED-NC Platinum in 2012, it cost $22 million to construct.
Facade Characteristics: The west facade consists of an aluminum rainscreen, high-performance windows that allow natural ventilation, and an external shading system operated by the building management system. The south facade uses a curtainwall system, parts of which include tinted glass, and a series of horizontal shading devices. The east and north facades minimize the window-to-wall ratio and have a high R-value to increase thermal resistance.
Case Study #2
Photo Credit: charles smith
University of Texas at Dallas Student
Services Building Richardson, TX
Building Description: Located in a hot climate, this 78,000- square-foot building provides enrollment, financial, and health services for students. Certified LEED-NC Platinum in 2011, it cost $20 million to construct.
Facade Characteristics: External shading is used on all facade sides except for north, preventing solar radiation from ever hitting the envelope. The system also utilizes a high-performance curtainwall to reduce solar heat gain, thereby decreasing its impact on the cooling load, while also allowing in daylight. Three internal atriums also splash natural light into most interior spaces.
Energy and Water at a Glance
|Center for Urban Waters
||University of Texas at Dallas Student Services Buildings
|Predicted Water Use Reduction – 46% less than building code requirements (system includes two 36,000-gallon aboveground cisterns that collect rainwater from the green roof and rejected water from reverse osmosis procedures conducted in labs. Collected water is used for irrigation and toilet flushing.)
||Predicted Water Use Reduction – 86% reduction in domestic water demand (Two 20,000-gallon cisterns are used to collect rainwater, which is used for irrigation.)
|Energy Use Intensity – 86 kBtu/ft2
||Energy Use Intensity – 82 kBtu/ft2
|Energy Savings vs. Standard 90.1-2004 Building – 36%
||Savings vs. Standard 90.1-2004 Building – 41%
|Annual Energy Cost Index – $0.83/ft2
||Percentage of Power Represented by Renewable Energy Certificates – 70%
|Annual Water Use – 476,626 gallons
||Number of Years Contracted to Purchase RECs – first two years of operation
|Heating Degree Days – 2,607 (base 65 degrees F.)
||Heating Degree Days – 1,265 (base 65 degrees F.)
|Cooling Degree Days – 74 (base 65 degrees F.)
||Cooling Degree Days – 1,533 (base 65 degrees F.)
|Average Operating Hours per Week – 80
||Average Operating Hours per Week – 112