Design and Construction of an Energy-Efficient Office Building
The Opportunity
Bautex Systems LLC manufactures a composite insulating concrete form (ICF) wall system that enhances energy efficiency and reduces the environmental impact of constructing and operating commercial and residential buildings. In 2013, the company started working with real estate developer Ironsight PSMT to design and construct an office building in San Marcos, Texas that would serve as Bautex headquarters.
The goal for the project was to design a roughly 3,900-square-foot office building that would significantly reduce energy consumption and improve indoor environmental quality, in contrast to office buildings in the region built using traditional construction materials.
Key Design Features
Continuous Insulation and Mass Wall System are based on the Bautex Block—a lightweight building block made from individual beads of expanded polystyrene (EPS) mixed with a proprietary cementitious material. These blocks are stacked to form a wall, then filled with steel-reinforced concrete to create a strong, insulated, and energy efficient building shell.
The R-14 continuous insulation provided by the wall system exceeded building code requirements and completely eliminated thermal bridging through the exterior walls. This significantly reduced the amount of thermal energy passing through the walls in the hot-humid climate of Central Texas. In addition, the thermal mass or heat capacity of the concrete walls also significantly contributed to the reduction of heat load on the interior of the building.
The afternoon shade provided by an existing building on the west side of the headquarters and energy efficiency was enhanced by the application of a full-width stone veneer on the south-facing side of the building.
Integrated Building Envelope Design
Other components of the building envelope included:
• Low-E insulated windows with thermally-broken storefront frame.
• Exterior doors that utilize a thermally-broken doorframe and Low-E insulated glass.
• Standing seam metal roof with a high Solar Reflectance Index (SRI) of 63.
• Ten-inch thick, R-38, open-cell spray foam insulation.
• Bautex Air and Moisture Barrier, sprayed onto all exterior wall surfaces.
Efficient HVAC and Lighting Systems
Efficient mechanical and lighting systems were installed to control building energy consumption. All interior lighting fixtures are LED and large, high efficiency windows on the north and east sides of the building provide significant natural light.
The heating and cooling system is divided into separate zones using Lennox variable speed systems with humidity control. Thermal efficiency in the construction means that the HVAC units generally operate at a lower speed, accelerating to a higher speed only for limited periods of time during the hot days.
Conclusion
The company will continue to monitor building performance in the years to come. Plant manager, Chris Leonard, whom leads R&D, also collects the building performance data. “We’re extremely proud of this product and the performance of this building,” he said. “Our office is proof that the Bautex Wall System is ideal for any office, commercial, or government building project that can be constructed quickly and cost-effectively while providing decades of extreme energy efficiency—and the reduced costs that come with that efficiency.”
“The building’s cost for lighting, heating and cooling is 59 percent lower than the energy consumption of the typical office building in this region of the country. The energy savings are projected to exceed $27,000 over 10 years,” said Oliver Lee, manager, Ironsight PSMT LLC
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