Facing the challenges of mixed-use buildings: sustainable buildings/energy efficiency
Fulfilling the demands of a mixed-use facility can be challenging, considering the structure’s diverse components. Here, professionals with experience on such projects share advice and explain how to end up with positive results for energy efficiency.
Dave Crutchfield, PE, LEED AP Principal, RMF Engineering, Charleston, S.C.
Julianne Laue, PE, LEED AP BD+C, BEMP, Senior Energy Engineer, Center for Energy Performance, M.A. Mortenson Co., Minneapolis
Robert Nixdorf, PE, LEED AP, Vice President, WSP | Parsons Brinckerhoff, San Francisco
Rodney V. Oathout, PE, LEED AP, Energy + Engineering Leader, Principal, DLR Group, Overland Park, Kan.
CSE: Energy efficiency and sustainability are often a request from building owners and chief information officers (CIOs). What net zero energy and/or high-performance systems have you recently specified on specialty projects (either an existing building or new construction)?
Nixdorf: Renewable energy generation is becoming a common feature of modern sports venues. Net zero energy remains an elusive goal for most projects, largely because of the high energy use intensity of this building type. Some universities have the opportunity to build PV arrays that are large enough to claim a net zero stadium, but offsetting the annual energy consumption of a stadium through building-integrated renewables is extremely challenging. High-efficiency lighting and HVAC systems can go a long way to reducing energy consumption. Cooling strategies, such as displacement ventilation under the seats, can significantly improve occupant comfort and reduce energy use was compared with conventional overhead cooling systems dumping air into the seating bowl. Due to the highly variable occupancy of an arena, they can be subjected to very high peaks in electrical demand. This is generally considered more of a cost issue than an environmental issue, but in reality, it is both. Building operators can incorporate strategies, such as precooling, and use of energy-storage systems can manage peak loads, significantly reducing energy costs. This also puts less demand on the grid, allowing more environmentally friendly electrical generation.
Laue: Achieving "net zero" is not a systems approach provided by the engineers, but a fully integrated design that involves passive and active design strategies from all designers. When teams take advantage of climate, envelope, HVAC, lighting, controls, products, etc., the chances of achieving a high-performance design increase. That being said, HVAC systems bear the brunt of the energy savings. On the air side, dedicated outdoor-air systems (DOAS) with energy recovery that are coupled with virtual routing and forwarding (VRF), chilled beams, and radiant heated/cooled slabs provide great efficiencies. At the plant level, ground-source heat pumps or high-efficiency boilers and chillers are a must.
CSE: What types of renewable energy systems have you recently specified to provide power for such projects? This may include PVs, wind turbines, etc.
Crutchfield: We often specify PV systems and provide economic analysis of the various renewable energy options for clients. With renewable energy incentives varying based on local/regional incentives, we have seen that two owners who are separated by a utility provider boundary may have vastly different payback periods.
Oathout: We have numerous examples of solar energy projects being incorporated into sports venues. Specific projects include FedEx Field, Lincoln Financial Field, MetLife Stadium, NRG Stadium, Levi Stadium, and the AmericanAirlines Arena. The intent of these projects is more than energy production; they strive to be a symbol of public outreach of the venue's renewable energy program and placemaking to supplement the entertainment value for the patrons.
CSE: Many aspects of sustainability (power, HVAC, etc.) require the building facility team to follow certain practices to be effective. What, if anything, can an engineer do to help increase chances of success in this area?
Oathout: We continue to stress the importance of the human element in building performance. Equipment and system designs have become more complicated to achieve the code, energy performance, and sustainability requirements of a project. Engineers need to fill the information gap with their owners by staying involved with projects after completion to ensure the stakeholders understand the design intent and maximize the performance of the facility.
Laue: Engineers need to push for greater involvement earlier on in the design process. We need to push the profession to be leaders of overall design teams vs. participants or subs to others. After a building is built, owners and occupants will adjust to the building program and aesthetics; but if the building is not comfortable, they will never be happy. We have a huge responsibility to the people within the buildings to provide them with spaces that are thermally comfortable, acoustically enjoyable, well-lit, without glare, and healthy. We need to be aggressive in design meetings and stress the value of the services we bring.
Crutchfield: With any high-performance buildings, the need to identify the maintenance staff and engage them in the design phase is critical. Engineers can benefit from their operations knowledge while maintenance personnel benefit from having an increased understanding of the design. After the design process is over and construction begins, we encourage maintenance staff to remain engaged in the construction process—to give them an understanding of how the design is being implemented. Then, after the construction process is over and the building is operational, the intrinsic knowledge they have of the design and construction process allows them to operate the building in a manner that retains the high-performance aspects.