Constructing Energy-Efficient Office Buildings

Building a high-performance office building at competitive market costs

In 2013, Bautex 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. This achievement would be a stark contrast to most office buildings in the region built using traditional construction materials.

Real Estate developer Ironsight PSMT constructed the building using Bautex Block — a lightweight building block made from individual beads of expanded polystyrene (EPS) mixed with a proprietary cementitious material. Bautex 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 Bautex 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.

Energy efficiency was also enhanced by the application of a full-width stone veneer on the south-facing side of the building.

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 under roof deck; and
  • Bautex Air and Moisture Barrier, sprayed onto all exterior wall surfaces.

Ironsight PSMT succeeded in designing and constructing a high-performing office building at a competitive market cost. Energy consumption has proven to be significantly lower than other buildings in the region, and indoor comfort is outstanding.

Monitoring data shows the building is averaging less than $125 a month (1,250 kWh/month) on average in heating and cooling costs. These savings, combined with the low cost to operate LED lighting, results in electrical bills below $200 a month on average (2,000 kWh/month).

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