How to engineer systems in mixed-use buildings: Electrical and power systems

When working on mixed-use buildings, engineers must address many needs in one building. Electrical and power engineering are key aspects of these buildings.

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Participants:

Mark Crawford, Principal engineer, Southland Industries, Las Vegas

Christopher M. Kearney, PE, LEED AP, Project manager, exp, Maitland, Fla. 

Brian McLaughlin, Associate, Los Angeles, Arup

 CSE: What’s the one factor most commonly overlooked in electrical systems in mixed-use buildings? 

Kearney: It is hard to narrow this down to one factor, but the first two that come to mind are metering and voltage requirements, since you may have 120/240 V single-phase for residential units and 277/480 V 3-phase for commercial areas. This will require input and coordination from the owner and utility company. 

CSE: Describe a recent project in which you had complex metering and submetering in a mixed-use building. 

Kearney: We are currently working on a six-story building that included two commercial retail tenants, apartments, and a multi-level parking garage with a fire pump. Separate metering was required for the fire pump, apartments, and retail tenants, which includes back-of-house power for lighting, mechanical equipment, etc. 

CSE: How do you balance the need for reliable power with the desire for efficiency and sustainability?

Kearney: When we incorporate renewable power sources (i.e., wind, solar, bio-gasification, etc.) into the building designs, we suggest the building should remain connected to the grid as the grid is your “battery.” With this design, there is no question about these systems’ reliability as they are there for their sustainability benefits. If the question is about having to have reliable power for a project (e.g., data centers), then it is just part of the project and sustainability is a completely independent issue. Efficiency and sustainability are becoming more and more important in all of the building types we work on. We must design more efficient buildings. This can be done by appropriately selecting system types and purchasing more efficient equipment in those systems. We must spend more money here. Renewables are an extension (not a substitution) of this foundation when we are reaching to become closer to carbon neutral projects.