Fixed exterior tinted glass overhangs help to reduce solar heat gain while allowing daylight into the interior spaces. Photo courtesy of Lawrence Berkeley National Laboratory; Photo: Weber Thompson

System of automated exterior venetian blinds and operable windows to manage daylight and ventilation. Photo courtesy of Lawrence Berkeley National Laboratory; Photo: Weber Thompson

Project: The Terry Thomas, South Lake Union, Seattle, WA

Owner: First Western Development

Architect: Weber Thompson

Design/Build Contractor: Mortenson Construction

Mechanical Engineer: Stantec, Inc.

Automated Shading
Thermal Comfort
Natural Ventilation

The Terry Thomas

The northwest U.S. climate made it possible for the design of The Terry Thomas to use natural ventilation and other passive strategies to meet occupant comfort and energy goals. Due to various site constraints, the building has a relative square footprint with a central courtyard, allowing for cross-ventilation and daylighting throughout all occupied spaces.

The north elevation of The Terry Thomas building. Photo courtesy of Lawrence Berkeley National Laboratory; Photo: Weber Thompson

To insure thermal comfort for the building's occupants, an extensive series of iterative thermal analyses were conducted to understand the effects of non-mechanical ventilation. Hourly temperatures in all spaces were determined then simulations were performed to calculate natural airflow patterns to determine whether or not indoor air temperatures did not exceed the prescribed limits. The comfort parameters of LEED NC 2.1 were used as a guide. Based on a typical meteorological year, it was predicted that temperatures exceeding 75°F and 80°F would occur for only 140 and 60 hours, respectively, during working hours. These analyses were conducted early in the integrated design process leading to decisions such as the minimum number of operable windows, areas of the facade that will need shading through automated exterior venetian blinds or fixed exterior shading, passive night cooling with thermal mass, and lighting controls. The analyses revealed the most effective strategies with regards to design, energy and budget.

Comfort Parameters
Temperature Occupancy Time
75–80°F< 150 hours
80–85°F < 50 hours
85°F + <20 hours

Interior showing daylighting penetrating into the open office space. Photo courtesy of Lawrence Berkeley National Laboratory; Photo: UW Integrated Design Lab

Energy consumption is reduced by the use of natural ventilation for cooling and radiant hydronic perimeter heating. The building's natural ventilation, without using mechanical force air, eliminates the energy consumption that would result from the use of cooling and fan systems Cross-ventilation is promoted by the narrow floor plate with a center courtyard and by the open office configuration. This cross ventilation is optimized by the use of automated louvers, castellated beams, and operable windows. The motorized louvers, use in combination with the operable windows, ensure that indoor air requirements and temperature setpoints are met. During the heating season, louvers are operated during occupied hours to not exceed maximum allowable CO2 levels in the space. During the cooling season, louvers are controlled by a thermostat and open when the outside air temperature is less than 78°F and at least 2°F cooler than a floor°s average common office temperature. During unoccupied hours, the louvers also night purge in select spaces during helping to reduce temperatures to meet the operator-defined setpoint.

The design team sought to provide daylight to all occupied spaces—both for the view connection to the outdoors and to reduce the need for artificial lighting. Daylighting analyses, performed with the thermal analyses, sought to balance the effects of glare and solar heat gain that could impede the natural ventilation. To maximize views and daylighting, design strategies using fixed exterior tinted glass shades, overhangs on the east and west elevations, and automated exterior Venetian blinds on the northeast street elevation and south, east, and west courtyard elevations were used. These automated external Venetian blinds have a dual motor so the daylighting portion of the blind can be controlled separately from the view portion.

The north elevation of courtyard showing the exterior stair to discourage elevator use and the daylight, view and ventilations systems. Photo courtesy of Lawrence Berkeley National Laboratory; Photo: Weber Thompson

The Terry Thomas building illustrates climate-responsive design that required an integrated approach to achieve the natural ventilation and human comfort goals. Iterative modeling and research resulted in a design approach to ventilation and daylighting that was holistic and successful at reducing energy consumption.

Sethi, A., T. Marseille. "Old Concepts, New Tools." High Performance Buildings. Summer 2010

Zelenay, K., M. Perepelitza, D. Lehrer. "High-Performance Facades: Design Strategies and Applications in North America and Northern Europe." Public Interest Research (PIER) Program, Center for the Built Environment, University of California, Berkeley, February 2011.


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