Optimizing Metal Buildings for HVAC

Drawing on experience with large-scale metal building systems, project teams face unique issues of design and optimization, as well as mechanical system planning, when they set out to build today. Project planning begins with a holistic analysis focused on anticipated uses and structural loads, as well as decarbonization and sustainability goals. Project teams should also consider factors such as passive heating and cooling opportunities, occupant wellness, as well as potential downstream changes of occupancies and uses. There are other considerations as well.

Design and optimization of large-scale, metal building systems requires careful planning and coordination for successful mechanical systems

By Phil Skellorn, CEng MICE, and Carlos Lopez, PE

The innovative modular design of the Michelle and Barack Obama Sports Center (Los Angeles) with its north and south operable walls was achieved in large part through careful collaboration involving Buro Happold’s engineers, SPF:a as architect, the general contractor, the metal building system provider, and client stakeholders.

Setting a basis for design and optimization—as well as cost savings—includes the integration of heating, ventilation and air conditioning systems (HVAC) and piping in the earliest project phases. This helps to accommodate proper attention to details for hanging pipes and mounting rooftop mechanical equipment, for example. Close engagement with the metal building system fabricator and contractor— and the full team, including the owner, architect and contractor, or OAC—is essential to success.

Energy efficiency and sustainability for the Obama Sports Complex were key concerns for the client group, so incorporating solutions like water recycling and integrated photovoltaics were at the forefront of the design team’s efforts for both structural and MEP strategies.

Establishing Basis of Design and Optimization

Metal building systems are intriguing for a number of reasons: Chief among them is the reduction in first costs possible with these building solutions, comprising a structural steel framing system and factory-made components, all customized to the specific project design requirements. Construction schedules and many of the building system costs can be highly predictable as compared to conventional construction, thanks to the controlled nature of manufacture, reduced labor inputs and reduced chances for job-site error.

Potential project cost reductions can benefit the client. However, for the projected cost savings to materialize, the OAC team must have an accurate portrayal of loads provided very early on in the project. This precise depiction of structural needs allows for not only a correct materials takeoff, but it also opens doors for a streamlined approach to the structure being designed. In addition, there is a tradeoff typically associated with this streamlining nature of metal building projects: It can come at a cost of future flexibility.

Consider, as an example, that the project team must be able to provide a basis of design for HVAC placement and pipe routing prior to final setting out of the building’s programming, interior space layouts and equipment. In a world where building usage often adapts to the financial opportunities (and challenges) the owner may confront, the decisions made in the concept phase could evolve considerably later on, downstream in the building process. This can prove challenging as the project moves onward to the construction documents (CDs) phase, where the options and feasibility of changes can be constrained.

Zooming in further, project experience shows that choosing to relocate mechanical system piping on a job site can be more challenging than expected. Seemingly minor changes can escalate costs and create related issues in metal building system project delivery. On the construction site, those small tweaks can have big impacts and take an unexpected bite out of the budget. This has happened on varied projects, and the key lesson learned by the OAC groups is to plan the structures in a different way—one that allows downstream changes with greater ease. For example, savvy structural designers will provide a more generalized pounds per square foot (lb/sf) in the areas where piping will be required. While this may be more costly for the client to begin with, it limits any potential issues in the future.

To summarize the opportunity: Getting ahead of the game, and setting a good basis of design, is vital to successful metal building project delivery. Communicating closely and frequently with the design team, and by allowing open and clear communications with the metal building system engineering group from very beginning, opens the door to more adaptable and positive outcomes. Even better, make sure this is a collaborative group dynamic that suites the preferences and work approach required or preferred by the fabricator. In this way, teams can define expectations and establish proper levels of communication between members of the team, based on project phasing, all while maintaining the preferred project schedule—which is often fast-tracked for a metal building project.

The Obama Sports Center’s efficient design and its added renewable energy make it possible to pursue the International Living Future Institute’s (ILFI) Net Zero Energy certification for the gymnasium, and to be the City of Los Angeles’ first net zero community center.

Design Team and Contractor Coordination

For metal building system project delivery, consider the coordination between the design group and the contractor as an opportunity for a proactive and potentially inventive new processes.

Part of what makes metal building projects so lean and cost-effective is that metal building contractors have a large chunk of the project, so they tend to walk to the beat of their own drum. They often work based on their own schedule, and they may be largely left to their own devices. This reflects the benefits of the metal building system and the primacy of this kind of contractor, yet it also raises potential challenges in the normal give-and-take of building project development. If changes need to be made to the metal building contractor’s structure, how difficult or easy will it be to negotiate successful resolutions?

With this in mind, savvy project teams recommend that the metal building provider be involved in all OAC calls. Some experienced OACs and consultants advise of steps to make sure the metal building provider is held accountable to give teams timely, accurate information during project delivery. In summary, the client group and OAC succeed by having a procurement strategy in place where the design team and contractor team can communicate and negotiate on-site. On the contractor side, everyone needs to be aligned for the construction type using metal building systems. The stakes are high, so the watchword is accountability. Contracts and procurement agreements can include language stressing the importance of defining accountability and responsibility between construction packages.

As an example, a metal building contractor may be incentivized to revert back to the basis of design and ask for change orders if something changes after the fact. The client group can remain firm, asserting that the metal building contractor is part of a team and not an individual delivery entity. For the most successful projects, the metal building provider remains present and helps find solutions to issues that inevitably arise long after the basis of design has been provided.

The lesson learned by experienced project teams: Press the client to ensure that the metal building provider is meetings its requirements. Empower the client to ensure that key contractor is always looking out for the best interest of the project.

Designed by SPF:a with Buro Happold providing MEP, sustainability and structural engineering, the Obama Sports Complex is a high-performance facility composed of two metal buildings systems totaling 40,000 square feet, and housing a 16,000-square-foot gymnasium, a 23,000-square-foot swimming facility, a walking track, seating area, and enclosed garden.

Design Details and Collaboration

Because metal building structural systems are different than those for conventional building structures, detailing how pipes are hung and how rooftop mechanical equipment is mounted, are very critical variables. Any deviation from the baseline scenario for the metal building structure could risk causing deflections to occur within the structure.

It is important that the metal building manufacturer own these details and not confer that responsibility to anyone else. Successful teams will have a general contractor and mechanical contractors who hold the metal building provider accountable to review hanging details and ensure everything is in line with the structure. Lesson learned: Ensure that the metal building supplier reviews all delegated design work that is in contact with the metal building structure. In this way, the project team can adapt the structure and the requirements of project to bring on board the full benefits of metal building systems.

Case Study: Obama Sports Center

Buro Happold, Los Angeles, and Los Angeles-based architecture firm SPF:a, liaised with client, numerous stakeholders and a project team to conceive and build a 40,000-square-foot, high-performance facility with 16,000 square feet of gymnasium, two pools in a 23,000-square-foot facility, as well as a walking track, seating area and enclosed garden. The design includes water recycling and a photovoltaic array that generates more than 13% of the building’s needed energy—critical to the solution, as energy efficiency is a key concern for the client. This was at the forefront of as the design team devised both the structural and MEP strategies for the complex.

The indoor pool facility, for example, is a key concern for a metal building. With significant humidity and condensation, the team had to determine ways to protect the building itself and ensure user comfort. Proper use of vapor barriers and careful insulation specifications were seen as essential to long building life. The design also carefully optimizes the use of windows, translucent panels and skylights for the energy efficiency of the building envelope. Studies conducted by the design team compared framing and glazing material choices and the ratio of glazed openings to wall and roof area based on the geography and climate zone.

Working closely with the OAC and the metal building system provider, the team created a modular design with north and south operable walls that open to provide natural ventilation as well as boost available area inside the building. A previously existing pool complex was demolished, though its original pool was adapted for use as a water cistern for reclaimed water, which is used throughout the complex. In addition to providing significant community amenities, this highly efficient design with renewable energy and reclaimed water meets the client’s sustainability goals, and allows the OAC and metal building to achieve higher ratings and greater contributions to sustainability and net zero goals.

Phil Skellorn, CEng MICE, is an associate principal, and Carlos Lopez, PE, is an associate principal at Buro Happold, Los Angeles.