Best practices for mixed-use buildings: Electrical, power systems

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. Electrical and power systems often have unique requirements.

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: Describe some recent electrical/power system challenges you encountered when designing a new building or working in an existing building. 
Lane: With the remodel of a historic site like Ivar’s Restaurant, there are many challenges. As the design progressed, we needed to ensure that the existing electrical infrastructure was modified to be code compliant and feed the proper load densities from the diverse loads from the kitchen, retail, office, and dock/shore power. Significant coordination with multiple design entities was required to ensure that the correct electrical infrastructure was located at the correct locations with enough power for today and future load growth.
Ahuja: Finding accurate existing conditions is always a challenge in existing buildings, and correcting existing code violations sometimes causes small modifications that can be very expensive and blow out budgets.
CSE: How do you balance the need for reliable power with the desire for efficiency and sustainability?
Lane: This is always a fine balance and is very dependent on the specific project, the local electrical codes, and energy codes as well as specific LEED goals. Communication and coordination with the owner and other design team members is critical.
Ahuja: We balance reliable power by right-sizing power and using intelligent diversity factors to avoid oversizing or too conservative designs.
CSE: What low- and medium-voltage power challenges have you overcome? 
Ahuja: Medium-voltage design skills are not common in traditional design firms. Also, maintenance people at facility are not trained properly to work on medium-voltage equipment, which causes challenges and avoidance of using these systems. Medium-voltage designs (where justifiable) are efficient system designs, both from a cost perspective and space requirements.