P2S Engineering Inc.: San Diego State University—Conrad Prebys Aztec Student Union

Automation, controls; commissioning, retro-commissioning; electrical, power; fire, life safety; HVAC, mechanical; lighting; energy, sustainability; plumbing, piping.

By P2S Engineering Inc. August 11, 2016

Engineering firm: P2S Engineering Inc.

2016 MEP Giants rank: 60

Project: San Diego State University-Conrad Prebys Aztec Student Union; LEED Platinum

Location: San Diego

Building type: Educational facility; engineered multidwelling/retail complex/restaurant; office building; sports/entertainment/convention center facility

Project type: New construction

Engineering services: Automation, controls; commissioning, retro-commissioning; electrical, power; fire, life safety; HVAC, mechanical; lighting; energy, sustainability; plumbing, piping

Project timeline: June 2011 to April 2015

MEP/FP budget: $30 million


The San Diego State University (SDSU) Aztec Student Union Center replacement design basis had two critical components: architectural consistency with the "California Mission" style of the SDSU campus and LEED Platinum certification, the highest level of building-resource efficiency awarded by the U.S Green Building Council.

The new building’s student-mandated LEED-intensive design posed significant and unique challenges while compounding the usual design and budget issues. Incorporating the many green design elements required for eventual LEED Platinum certification in such a large, multistory, multifunction building was just the sort ingenuity-straining project that P2S engineers relish. As the project’s mechanical, electrical, plumbing, and technology (MEPT) design partner, P2S Engineering contended with the challenge of implementing sustainable design features throughout the building’s HVAC, electrical, and plumbing systems to the extent required to meet LEED Platinum standards—and to do it all within budget.

The first challenges consisted of identifying potential LEED points and deciding on the specific technologies to implement therein. P2S considered many different approaches to that task; and, for each promising solution, P2S calculated feasibility, costs, payback metrics, and LEED points. After thorough analysis, P2S determined that a hybrid approach incorporating traditional engineering methods along with innovative green engineering technologies was the best, most cost-effective approach to meet the LEED Platinum challenge.

Identifying the best complementary engineering methods to use in different parts of the building was a significant challenge, yet more demanding challenges particular to the implementation of these technologies followed. For example, P2S decided to implement radiant heating and cooling systems on all three floors of the building’s west wing. Effectively installing these systems was no easy task and demanded close attention to avert potential complications. During the San Diego summer, heat from outside would result in condensation on the cold floor, making it slippery, which is a massive hazard for occupants. The radiant cooling system had to be paired with something other than natural ventilation to eliminate this risk. Operable windows would be used in other parts of the building and would be paired with low-pressure variable air volume (VAV) systems.

Illuminating a building with such disparate lighting needs also proved challenging. P2S had to resolve the issue of providing exceptional day and nighttime illumination in a manner that was energy- and cost-efficient and consistent with LEED Platinum levels of energy consumption. It became evident early on that a composite lighting strategy incorporating various methods would be necessary to meet the building’s lighting needs and LEED Platinum standards. Solving this challenge required P2S to devise an optimally balanced lighting and electrical strategy using appropriate technologies to maximize illumination and reduce operating costs.

Significantly reduced water consumption is an important factor in achieving LEED Platinum status. The building’s exterior irrigation needs and interior water-usage requirements became the basis of a comprehensive water-use reduction strategy, which would eventually encompass sustainable water-reclamation and -saving strategies.


P2S Engineering was pleased to be able to provide a complex range of sustainable water- and energy-saving solutions that simultaneously reduced resource use and operating costs while maximizing occupant comfort and sense of well-being.

The new Conrad Prebys Aztec Student Union’s HVAC system consumes 40% less energy than Title 24 standards and incorporates several low-pressure VAV systems with economizers to allow for appropriate flow depending on need. Parts of the building were equipped with a radiant slab-heating and -cooling system with a dedicated outside-air system to simultaneously reduce fan energy and improve indoor-air quality. Carbon dioxide sensors also provide demand-based ventilation for high-occupancy spaces. Exceptional airflow and ventilation are also aided by operable windows, which reduce energy consumption and offer natural airflow.

The Aztec Student Union building’s lighting system comprises an effective mix of natural light, which shines through daylighting and skylight features, and innovative electrical design, which includes highly efficient light fixtures throughout the building and different sorts of localized task lighting to contrast and illuminate the interior spaces within the building. Demand controls to harvest daylight savings and reduce overall lighting power densities were also used within the electrical systems, and energy-efficient distribution transformers helped to further reduce energy losses.

In another sustainability coup, P2S designed and implemented a photovoltaic (PV) system on the roof. The PV system functions to offset a portion of the building’s energy usage with the provision of onsite renewable power. P2S also made the most out of the building’s exterior apex by employing a "green roof" strategy, which reduces the energy-draining heat island effect while promoting a natural habitat for local fauna.

The project also features water-permeable paving with underground water storage to reclaim and save rainwater for landscape irrigation and eliminate discharge into the municipal stormwater system. As a final touch, P2S included the submetering of all utility systems within the building to allow the university to better understand and, if necessary, respond to energy- and water-consumption patterns.

The completed 206,000-sq-ft structure houses a 300-seat multipurpose theater room, a 1,200-seat ballroom, a recreation center with bowling alley, dining and retail spaces, and the student community affairs offices. The new building presents reported annual energy and cost savings of 49.8%, as compared with the previous structure, and is indeed on track to become the largest LEED Platinum education building in California. Additionally, during design and construction, P2S was able to validate the performance of the building through the first year of operation through execution of the meaurement and verifcation (M&V) plan. From the analysis of trend data and calibration of the energy model, the building actually performed better than projected.