Levi’s Stadium, Santa Clara, Calif.
Enough solar energy to make the stadium net-neutral for each 49ers home game. One hundred million gallons of drinkable water saved since 2014. Solar energy and water savings are just two areas on which the Levi’s® Stadium operations team has focused. They continually use operations and maintenance to create a more energy-efficient stadium and set an example for other venues.
Energy conservation has been part of the DNA of the San Francisco 49ers stadium from the start. In August 2014, Levi’s Stadium became the first professional football stadium to open with LEED BD+C: New Construction v2. Less than two years later, in July 2016, the stadium achieved LEED O&M: Existing Buildings v3, making it the first NFL stadium to be LEED Gold certified under those two rating systems.
For the operations and maintenance (O&M) certification, the team focused primarily on implementing practical and measurable strategies aimed at achieving high performance in sustainable site development, water savings, energy efficiency, materials selection, indoor environmental quality and maintenance enhancements. Over the course of almost a year, the stadium implemented strategies including:
- Installing efficient water fixtures to reduce water consumption by 44%.
- Offsetting 37% of its electricity and natural gas use with Green-E certified renewable energy credits (RECs) and nearly 20,000 square feet of solar panels.
- Making strides in expanding waste reduction efforts beyond current diversion rate nearly 63% waste from the landfill.
- Going well beyond the performance threshold level of existing LEED credits by purchasing 100% Energy Star qualified equipment.
- Maintaining a sustainable purchasing program for cleaning materials and products, disposable janitorial paper products and trash bags, where 85.9% of the purchases satisfied sustainability criteria.
- Developing and implementing an indoor air quality (IAQ) management program based on the U.S. EPA standards to maintain a healthy and comfortable working environment for building occupants.
- Using filters with a minimum efficiency reporting value (MERV) of 13, which provide higher quality air to occupants and remove pollutants.
- Using cleaning equipment that are Carpet and Rug Institute (CRI) Green Label tested and that use high-efficiency particulate air (HEPA) filters.
Levi’s Stadium also continues to operate at its previously achieved LEED certification for implementing practical and measurable strategies aimed at achieving high performance in sustainable site development, water savings, energy efficiency, materials selection, indoor environmental quality, and maintenance enhancements.
From three solar array-covered pedestrian bridges, which connect fans from the parking lot to the stadium, to more than 1,000 state-of-the-art solar panels fixed atop the venue, Levi’s Stadium is net-neutral to the grid for the 10 scheduled 49ers home games each season, drastically reducing the stadium’s overall carbon footprint. The solar panels offset electrical utility consumption for all NFL regularly scheduled games, for a total of 464 MWh. Electrical vehicle charging stations are located on the west side of the stadium to power electrical vehicles for visitors and staff year-round, including event days.
Levi’s Stadium’s 2017 site energy use intensity (EUI) is 65.1 kBtu/ft2·yr (with solar included, the EUI is 63.9 kBtu/ft2). This is an 18% savings from its 2014 EUI because of implemented efficiency upgrades.
The main source of energy is electricity. The two sources of 12 KV are fed from two independent electrical high voltage switching substations. The stadium’s 12 megawatt designed electrical system with an automatic “tie switch” is able to keep Levi’s Stadium powered if an outage occurs on one of the services. This redundancy allows the stadium to operate at 100% once the primary electrical switches. A secondary source of electrical energy is the solar system that feeds back into the electrical grid, offsetting electrical consumption on a daily basis.
Natural gas is used at Levi’s Stadium for heating domestic potable water and HVAC hot water loop for environmental systems (heating) throughout the venue. More than 40% of the natural gas consumption comes from cooking at Levi’s Stadium, which has more than 40 different concessions stands and kitchens.
Low-flow plumbing fixtures such as toilets, urinals and sinks continue to use 40% less water than conventional fixtures. On top of low-flow water fixtures, the stadium uses recycled water for flush fixtures, which make up 85% of overall water use. The recycled water in the stadium is from the Santa Clara County recycled water plant, which uses reverse osmosis, micro-filtration, as well as ultraviolet technology to treat the sewer water before being redirected to the stadium. Moreover, the recycled water skid is a four-stage pump system with soft start control. The suction draws off a 15,000 gallon above-ground tank where recycled water is stored, keeping a controlled level of 8 feet of tank head pressure. The system uses a sand filter with backwash to minimize any foreign objects or contaminants entering the system. Recycled water is also used for all irrigation, including the playing field.
The playing field is surrounded by a 23,000 square foot artificial turf track that reduces watering needs by approximately 20% and reduces the amount of natural grass needed for the venue’s 2-3 field resurfacings per year.
Potable water accounts for 15% of overall water use. To help reduce potable water needs, water restrictor shower heads and low-flow hand wash stations are used. A domestic water pump system serves all potable water for the entire facility. The skid is a three-stage pump system with soft start control that uses a water softener filtration system to remove hardness from supplied city water.
Later this year, Levi’s Stadium will reach 100 million gallons of potable water diverted—meaning the stadium, in just four years, will have saved enough potable water to fill the 68,500 Levi’s Stadium bowl from the field up to the 300 section.
The stadium’s cooling source is provided by a variable flow condenser water system, and the building’s cooling load is approximately 2,400 tons. The condenser water system is equipped with four cooling towers, two 100 hp open-loop variable speed pumps, a twin 200 hp closed-loop variable speed pump, a pair of plate-and-frame heat exchangers, a water filtration skid and three expansion tanks. The condenser water systems serve all of the variable air volume (VAV) air-handling units, water source heat pumps, the food service freezers and coolers, beer distribution system and ice makers.
The heating water plant consists of five 3,000 MBH condensing boilers, two 40 hp variable speed pumps, and a pair of expansion tanks. Heating hot water is used for all VAV box reheats throughout the stadium, and every VAV box is equipped with a reheat coil. The hot water system is designed to be variable flow with two-way valves located at all hot water coils. The heating water system also supplies water to the air-handling unit preheat coils and the makeup air-handling units.
A lighting controls system has been installed, equipped with daylight harvesting, occupancy sensor and sweep ON/OFF lighting controls. Photocell sensors are located in the elevator lobbies and atrium of the stadium’s suite tower to help reduce energy consumption when sufficient natural light is available. Private suites, administration areas, back-of-house areas, concession stands and all other areas are equipped with occupancy sensors, which sweep off the lights when no occupancy has been detected for 30 minutes.
Two types of systems are installed in the stadium: stand-alone systems controlled via local lighting control panels and a lighting control and energy management system, which integrates specific areas into a software-based interface to allow the stadium operations group to program schedules or manually switch on or off the lights in a given area. Sweep lighting controls can be programmed to a user-defined schedule to ensure all lights are swept off at the end of the day. Lighting overrides can be accomplished via any local switch on an as-needed basis.
A key component of a capital improvement project completed at Levi’s Stadium in 2017 included LED lighting retrofits throughout the stadium. Replacing fluorescent and metal halide lamps with LED lights has saved the stadium 150,000 watts, improving the lighting quality and life-span of newly installed lamps. Levi’s Stadium’s goal is to save an additional 200,000 watts with lamp replacements over the next several years, with the end goal to be 100% LED within the next five years.
After enhancing the engineering control console (ECC) in 2016 as part of that year’s capital improvement projects, the stadium—over the past year—has seen a drop in its utility use of 18%. The ECC has been instrumental in achieving that figure, as it constantly monitors trends, adjusting and turning systems on and off through an automated schedule of events for the day throughout the stadium.
|Lessons Learned: Rectifying Inefficiencies|
Though Levi’s Stadium achieved dual LEED certifications, its operations management determined inefficiencies in building performance and sustainable efforts. These challenges to building and/or sustainability efficiencies were rectified through the execution of annual capital improvement projects. Here are two examples:
After just a little over a year in operation, we saw that we wanted to decrease our energy output, so a key component to our 2016 capital improvement project was an upgrade of our engineering control console (ECC). The upgrade involved enhancements to the ECC where all systems were interfaced through industry standard RS-232, BACnet or Modbus protocols. The stadium’s electrical, lighting and mechanical systems (from different manufacturers) are able to share information, making sure the systems are operating at high efficiency. For instance, the lighting occupancy sensors report to the management system, letting the VAV zones know when rooms are populated.
Also the power monitoring system reports to the management system with the current building and mechanical equipment electrical load. These systems are monitored through seven 55 in. large flat screens with video matrix control for constant monitoring, trending, adjusting and turning systems on and off through an automated schedule of events for the day.
By implementing the automated scheduling and integration programming of systems, we have been able to drop our overall utility use (natural gas and electricity) of 18%. Even though we saw a significant drop in utility use over one year due to the ECC upgrade, we still wanted to find ways to minimize electricity use. Therefore, a key component of the 2017 capital improvement project included LED lighting retrofits throughout the stadium.
To ensure the stadium’s water system runs more efficiently, one of the capital improvement projects for 2017 included the installation of a water softener for the cooling tower system. This system uses recycled water to supply condenser water to the many environmental and refrigeration systems throughout Levi’s Stadium. By installing the water softener, Levi’s Stadium will be able to eliminate the hardness of water so that systems run more efficiently and are more dependable by ensuring longevity of equipment is not affected by contaminants and minerals that can build up in the piping system over time.
The stadium’s Solar Terrace houses a 27,000 square foot “green roof.” This living roof features 16 species of vegetation native to the Bay Area to lower the building’s cooling and heating needs by regulating ambient temperatures in the stadium suites that are under the green roof. And, a portion of the roof is shaded by the solar panel canopy.
In 2016, Levi’s Stadium partnered with a California urban farming company to create the first rooftop farm at an NFL stadium: the Faithful Farm. The 7,000 square foot rooftop farm is located on the Solar Terrace and supports nearly 40 rotational, fresh-tilled crops. Produce and herbs grown on the roof include tomatoes, summer squash, peppers, sweet peas, brassicas, eggplants, pumpkins and basil, generating an annual yield of more than 7,500 pounds. All crops are harvested and used in-house for suite and private event catering at Levi’s Stadium. Any excess food is made available to a local food bank.
Levi’s Stadium was designed to serve as an example for sports organizations and facilities around the world. The building managers continually look for ways to incorporate more sustainability into their operation plans to show other sports and entertainment venue managers that sustainability should be a critical part of their plans as well. •
ABOUT THE AUTHORS
Jim Mercurio is the vice president of stadium operations and general manager of Levi’s Stadium. Emily Lucas is the manager of corporate communications for the San Francisco 49ers.