First Baptist Church
The 275,000 sf First Baptist Church is located in the heart of downtown Dallas. Consequently, the building has four primary facades. The majority of the east, west and south exposures feature a pre-insulated, custom-designed precast concrete wall system which is both aesthetically pleasing and energy efficient. The LEED Silver project is comprised of a worship center, children's education building, skybridge, connecting concourse and parking garage.
The biggest challenge for the architect was finding a highly thermally resistive material for the harshest sun exposure areas that would also be aesthetically pleasing. To achieve these goals, Gate Precast worked in a design assist basis with the architect. The High Performance Precast Wall system consists of a 3" exterior wythe of precast concrete featuring a custom-designed basket weave pattern; a middle 2 inches of insulation and an interior 3-inch wythe. The result is a very efficient thermal protective skin that provides a beautiful facade. The use of 3D modeling was extremely beneficial on this project,
Precast System Details
- 35,000 Square Feet of Architectural Precast Concrete — A light buff mix was used wth a medium sandblast finish.
- 3"-2"-3" Thermomass Insulated Panel — 2-inches of Isomass polyisocyanurate insulation with CC Series composite connectors to develop composite action between the two wythes of concrete.
- Horizontally Cantilevered Panels
Precast Concrete Advantages
- Aesthetic Versatility - Innovative Custom Formliner
- Improved Thermal Performance - Reducing Energy Consumption
- Helped Meet Sustainability Goals
- Mold / Mildew Resistant
- Minimal Maintenance Cost
- Highly Durable
- Reduced Trades
- Indoor Environment Comfort
The steady state thermal analysis shows the total isothermal R-value for the wall, with the ability to factor in thermal breaks such as metal ties or solid concrete sections. When calculating a THERMOMASS panel, there are no solid concrete sections and non-conductive fiber composite ties are used, so there is little loss of energy through the wall. The steady state values for the 3"/2"/3" THERMOMASS wall is 14.14, which equates to an energy loss of less than 2% of the assumed R14.32. The competing 6" solid panel with steel studs and R19 batt system loses much of its assumed R-value through the steel studs, and its overall R-value is 8.29, which is equates to an energy loss of 62.13%.
The Envelope Performance Study shows the effect of thermal mass on a building. Since THERMOMASS is an edge-to-edge insulation system without thermal bridges, it maximizes the thermal mass effect of concrete, thereby reducing the heating and cooling loads and provides an R-Value greater than what can be expected by the material alone or by which code requires. Depending on a number of factors including climate data, building orientation, occupancy type, and facility size, the THERMOMASS wall can have a much greater mass corrected R-value. By using the ASHRAE Standard 90.1: System Performance Criteria calculation in the case of the 2” THERMOMASS insulated wall, an equivalent R-value greater than R19 is achieved.
The dewpoint analysis uses the theory of vapor migration to graph where and when moisture accumulation may occur within a wall section. This program charts actual and dewpoint temperatures, and depending on where and if they cross within a wall section, there may be potential for accumulation. Cause for concern depends on the amount of accumulation, and where in the wall section it would occur. In this case, there is no concern for water accumulation during the summer because the dewpoint and actual temperatures do not cross within the wall section. The opposing system does have moisture accumulation in the insulation, roughly 33 times more than what we typically consider to be acceptable.