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L|F San Antonio Office Goes Zero Carbon with Big Sun Solar

311 Third Street, our San Antonio office, was built in 1920 and was originally designed for Hupmobile, an automobile company. “In 1985, David and Ted bought partial ownership in the building, and started Lake|Flato Architects on the south side of the second floor. The firm expanded to the second floor north side in 1990, the third floor in 2003 (when Ted and David took full ownership), and the entire first floor in 2005. In 2008 we completed a full renovation of the main level." (to read the full story check out: Better Know an L|F Project: 311 Third Street | Lake Flato)


Today (2021), we are working on another renovation for the office. One of the goals of the renovation is to achieve the International Living Future Institute Zero Carbon building certification. The Zero Carbon Certification requires “100% of the operational energy use associated with a project must be offset by new on- or off-site renewable energy. 100% of the embodied carbon emissions associated with the construction and materials of a project must be disclosed and offset.” By achieving zero carbon in both operational and embodied carbon, we can also demonstrate our commitment to the 2030 Challenge goal of meeting carbon neutrality by 2030. In this post, we are focusing on how we are going to achieve the operational energy portion of the certification.

A major challenge to this certification is achieving 100% of operational energy from on- and off-site energy to achieve net-zero energy. Net-zero energy is best defined as producing as much energy as consumed in a year through renewable energy. Currently, the building has a 10 kW solar array on-site that was installed in 2012 which provides about 5-10% of the annual energy needs. At the time, this was the largest array we could have installed for several reasons including limited roof space and adjacent shading from other buildings and our own. One of the major challenges was the limitations on downtown properties per CPS Energy's (San Antonio’s local power utility) distributed generation guidelines. This is a common guideline in any downtown with uninterruptible essential services -- you can't send more power back to the grid than you are consuming instantaneously which limited us to a 10kW array on site.

We will be keeping this array and moving it to the upper roof after the renovation, but are still limited to a max of 10kW on site. Part of the renovation includes reducing our energy demand first, then offsetting the remaining energy needs with more solar panels. With the building undergoing a renovation, there were lots of opportunities to reduce our energy demand through strategies such as introducing a new, more efficient HVAC system, reducing plug loads, as well as metering our circuits to track energy use and adjust during occupancy. Although we were able to reduce our energy demands, increasing our solar energy generation was necessary.


To achieve net-zero energy in the high-density urban core with limited roof space, we partnered with Big Sun Solar to add off-site solar generation to our project. Big Sun Solar is a San Antonio-based company that builds, manages, and maintains both on- and off-site solar within the San Antonio area. Off-site solar is a great opportunity for building owners who want to achieve net-zero energy but may not have the space on-site such as on your roof or property. To participate in the program, you simply purchase a specific system size and Big Sun Solar installs it at an off-site location. All of the solar installed off-site is on carports over parking lots, which not only generate solar but provide shade to those using the parking spaces which is highly beneficial in hot southern climates like Texas.  Our off-site solar is a 201 kW array located at Walker Ranch in San Antonio and produces approximately 265,000 kWh/year. This is equivalent to reducing 30,969 co2 tons per month which is equivalent to planting 489 trees a month. 

 The energy produced is then sent to CPS Energy’s grid and the credit is applied to your bill. Since Big Sun Solar operates in partnership with CPS Energy there are several advantages to this solar offering. While the specific portion of the PV array is owned by Lake Flato, the panels are optimally installed for orientation and free from adjacent shading elements. The array is also operated and maintained by experts to operate optimally across their full lifespan. The created energy is fed directly into the power grid and the firm’s utility bills are automatically adjusted every month, where excess is carried over. By investing in off-site solar, we are able to still achieve net-zero energy and zero carbon efforts in combination with our on-site 10kW array on the building and serve direct on-site energy needs. This process is also available for residential homes that may not have access to a viable roof and has been implemented by six of our own staff who want to “practice what they preach” by participating in Big Sun’s program.

As the firm continues to grow, the timely renovation of our 311 Third building has presented a unique opportunity for us to transform our office into a high-performing building that is appropriate for a post-pandemic workplace and beyond. In a recent interview with the San Antonio Business Journal, Lake|Flato Partner Brandi Rickels said it best: “We hope to create an inspirational, healthy and flexible workplace that showcases our passion for timeless design that connects to nature, promotes sustainability and highlights regional materials and craft.”



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