The design of the new 275,000-square-foot General Services Administration GSA Office Building in Houston, Texas, is generated by careful integration of concerns for security, sustainability and appropriate image into a thoroughly synthesized design solution. Rather than viewing these as independent design parameters, this project addresses multiple issues concurrently and accomplishes a broad range of goals seamlessly and economically.
In response to climate considerations, the plan is narrow, presenting broad faces to the south and north, and thin faces to the east and west. The concrete walls are sheathed in aluminum shingles that both reflect heat and allow the high thermal mass of the concrete to provide temperature stability for the structure. A lightweight metal frame was hung off of the concrete walls to carry a second skin for the building on the south, east and west sides. Heavily fritted laminated glass is attached to the lightweight frame with stainless steel clips. The almost opaque glass, which is placed away from the actual thermal wall of the building, shades the structure substantially from direct heat gain from the hot Texas sun. The space between the two skins becomes a significantly cooled microclimate reducing the load requirements for air conditioning systems. In winter, the glass layers enhance the heat-insulating functions of the facade owing to the comparatively higher surface temperatures of the inner surface of the facade.
The north side of the eight-story building, where no sun protection is necessary, has no second skin. The aluminum surface is fully revealed and is animated by varied window patterns reflecting the extremely divergent view and lighting requirements of functions on this face of the building.
During schematic design sun angles were analyzed, optimizing distance between facades. Apertures in the glass skin, sized somewhat smaller than the actual windows, are carefully placed to provide excellent day-lighting with reduced glare for interior work spaces. The large window openings nearly nine feet high are made of various modules developed so the interior partitions could abut in appropriate places on the very large glazed frames. They incorporate yellow, composite panels in a non-symmetrical patterning to accommodate flexible interior office space partitioning. For building occupants, vision glazing not only admits generous quantities of light but also provides a broader sense of the outdoor landscape, providing a safe and healthy working environment.
The exterior glass skin is carried into the lobby, reinforcing the connection of indoors and outdoors. The security design guidelines were implemented through the use of filtered circulation paths and controlled sequence of spaces that conveys the sense of an open-door policy without compromising the safety of the staff.
The high performance skin of the building is also employed as a major image generator. Because of the depth and richness of the buildings surface its massing could be kept very simple and economical. The aluminum shingles provide a bright, neutral backdrop on which to project the constantly changing light and shadow patterns from the glass skin. Colored a deep, rich green, the glass mutes the bright sun and lends it a striking hue. The green floating, glazed facade aesthetically conveys a sense of lightness that a conventional solid wall cannot. In the lush green context of suburban Houston the color of the building feels natural and integral. Tall cottonweed trees near the building on the south side complement the colors and delicate articulation of its surface.
This careful balance of opacity and transparency, solid and void, closure and aperture, expressed with the articulation of metal and glass, serves to communicate that this is a strong and secure facility that, while protected, is nonetheless welcoming and accessible. By integrating concerns for function, technical performance, and mission-specific requirements into well-synthesized holistic design solutions, the building creates a simple, elegant, and economical building well-suited to its specific purpose and the goals of its agency. The GSA office building is both an inspiring workplace for its employees and an efficient facility for the citizens it is serving.
Sustainable Design / Energy Efficiency
The GSA building has been carefully designed to maximize environmental sensitivity, promote daylighting and views, and provide for the potential of solar energy capture.
The heating, ventilation and air conditioning building services infrastructure was designed to provide long-term reliable service optimized for energy efficient operation in Houstons hot and humid Gulf Coast climate. Energy recovery units greatly reduce the energy needed to condition the hot and humid outdoor air while improving indoor air quality for building occupants. Strategic location of CO2 sensors optimizes the delivery of conditioned ventilation air to address occupant demands without operator intervention.
Systems were designed to conserve energy during part-load operation. Equipment utilizes the variable speed technologies to optimize part-load energy efficiencies for pumps, chillers and cooling tower fans. Integrated building management systems communicate and are designed to adapt, allowing for critical tenant functionality during extended periods when utility services are disrupted.
Sustainable design strategies in addition to the dual skin microclimate, daylighting and HVAC systems discussed previously include:
Careful location of the buildings and paved areas to preserve several stands of existing trees
Location of swales and berms to minimize erosion and runoff
Site selection adjacent to mass transit facilities and above the 500-year floodplain
Bicycle storage and changing facilities
Reduction of heat islands via the use of covered parking
Elimination of visual light pollution by careful specification and location of light fixtures
Water efficiency through the selection and use of drought-hardy landscaping, rainwater harvesting, low-usage plumbing fixtures and cooling tower water recycling
Reduction of energy costs through the use of high-performance glass, high insulation values, dedicated energy recovery units, and special selection and design integration of energy efficient HVAC systems, including a full building under-floor HVAC system
Specification and design that integrate a high percentage of recycled and locally harvested materials
Exceptional indoor environmental quality that includes CO2 monitoring and low VOCs for all interior materials
Substrate for future thin-film photovoltaic application at the discretion of the owner provided by the screenwall system