Best practices for mixed-use buildings: Codes and standards

Taking on a mixed-use structure—such as one that includes retail and residential portions—can be an engineering challenge. With all the different engineered systems involved, it can be like working on and integrating several different projects at once. Building codes and standards are key to the success of these projects.

By Consulting-Specifying Engineer September 29, 2014


  • Anil Ahuja, PE, RCDD, LEED BD+C, CxA, President, CCJM Engineers Ltd. Chicago
  • Jason R. Gerke, PE, CxA, LEED AP BD+C, Mechanical and Plumbing Team Leader, GRAEF, Milwaukee
  • Keith Lane, PE, RCDD, NTS, RTPM, LC, LEED AP BD+C, President/CEO, Lane Coburn & Associates, Bothell, Wash. 
  • Brian A. McLaughlin, PE, Associate, Arup, Los Angeles

CSE: What codes, standards, or guidelines do you use as a guide as you work on these facilities?
McLaughlin: From a life safety standpoint, codes based upon the International Building Code (IBC) and International Fire Code are common. This is true both within the United States and around the world. At times, owner requirements often drive the use of specific regulations; for example, many international hotel chains have brand standards that they seek to incorporate for all projects globally in order to introduce consistency for their properties. NFPA standards are also heavily prevalent around the world, especially with respect to sprinkler and fire alarm system designs.
Gerke: Of course, the project location will affect which codes are required. There are numerous standards that need to be considered for these building types. These standards include ASHRAE, IECC, and NFPA among others. Many times codes are based on the International Code Council (ICC) volumes with varying years of adoption, but again the local authority having jurisdiction (AHJ) may require other codes to be observed. The design team needs to be careful to identify early in schematic design any conflicts  between the codes requested by the AHJ, your company’s design standards, and other industry standards for design.
McLaughlin: From a life safety viewpoint, I do not believe that one specific code offers more challenges than another. With regard to code-related challenges, I think that U.S.-owned properties overseas offer a unique challenge in that there is often a need to balance the owner’s desire to comply with U.S.-based codes such as the IBC and the local regulations that must be followed in a particular jurisdiction. It is these projects that offer a fire and life safety consultant the opportunity to truly develop a holistic approach to achieve the required level of fire and life safety for the project that meets all of the stakeholders’ goals.
Lane: We always have to follow NFPA 70: National Electrical Code (NEC). Seattle has just approved the 2014 version. Then we have to follow the Seattle Electrical Codes, which are amendments to NEC. Then Seattle has a very strict energy code. There are some exceptions for retrofit projects. If the project is on the waterfront, there are specific rules that are required in addition to the NEC. The lighting also typically has to be dark sky compliant. If a new service is required, then coordination with Seattle City Light is also required. Additionally, there are standard meter sizes that need to be considered for the specific tenant loads.
Ahuja: The local governing code is typically mandated by the village or city that your project is located in. In our office, we are typically bound by the City of Chicago Code, and the International Energy Code. Most suburban projects rely on IEC, NFPA, and either the International Mechanical Code or ASHRAE as their guideline.
CSE: Have Energy Star, ASHRAE, U.S. Green Building Council, etc., affected your work on mixed-use building projects? What are some positive/negative aspects of these guides?
Ahuja: Many projects are requiring some sort of LEED certification, and so the U.S. Green Building Council and ASHRAE are used quite frequently on most projects. Many of the positive aspects are in relation to energy efficiency. As a brief example, the requirement to provide an energy-efficient building envelope leads to less heating and cooling loads, which leads to smaller equipment, which leads to more energy efficiency and less fuel consumption costs. Some of the downsides are upfront costs often outweigh payback, and costs of certification are often more than a client is willing to bear.
CSE: Which code/standard proves to be most challenging in such facilities?
Ahuja: Oftentimes it is the conflicting nature of multiple codes that creates the challenge. As an example, the City of Chicago requires that all occupied spaces be provided with a minimum of 33% direct outside air (OA) via the HVAC system. The IECC requires heat recovery on any HVAC system greater than 5 tons cooling capacity, and with more than 30% direct OA. In order to achieve the LEED enhanced ventilation credit, one must provide 30% more ventilation than required by ASHRAE, and have airflow measuring stations in the OA, return air (RA), and supply air (SA). In order to provide a system, all of these codes must be considered and applied, and equipment provided to accommodate all of the varying requirements. This, in many cases, is the greatest challenge of design.
CSE: Do you find codes affecting mixed-use structures to be more or less taxing than those impacting work on other building types? If so, in what ways?
Ahuja: The codes from an engineering standpoint generally are not any less or any more taxing in mixed-use versus single occupant spaces. Mixed-use facilities with kitchen and restaurant or assembly areas require multiple sections of code to comply to and cause an interpretation challenge.