Designing office space: Electrical, power systems
Michael F. Cooper, PE, LEED AP, Managing Principal, Harley Ellis Devereaux, Southfield, Mich.
Kurt Karnatz, PE, CEM, LEED AP, HBDP, HFDP, President, Environmental Systems Design Inc., Chicago
Kent W. Peterson, PE, FASHRAE, LEED AP BD+C, BEAP, Vice President/Chief Engineer, P2S Engineering Inc., Long Beach, Calif.
CSE: What’s the one factor most commonly overlooked in electrical systems?
Cooper: The most overlooked element in electrical systems is planning for the future. We know that once these systems are installed, it’s costly and disruptive to modify or expand them. We also know that changing tenant needs are driving the need for system adaptability. Information technology alone has driven significant changes in electrical systems design. It’s critical that time is taken at the start of each project to assess the needs of today and tomorrow and how today’s systems can help facilitate future growth.
Karnatz: Power quality. While the total power required on a W/sq ft basis is trending down for office occupancy, the need for power quality and reliability is not.
CSE: Describe a recent project in which you had complex metering and submetering in a building.
Karnatz: As previously mentioned, large office buildings with multiple and diverse occupancy needs very often require complex metering schemes. In buildings where there is a great diversity in tenancy and therefore infrastructure consumption, the need to accurately allocate use costs is very important. Very often buildings have some tenants that might consume three to five times the amount of power and cooling that others consume.
Cooper: One recent project, which achieved a U.S. Green Building Council LEED Platinum Certification, included a building distribution system segregated by load type as well as metering at each tier of the system to for real-time monitoring and management. “Dashboard” displays throughout the facility indicate real-time usage and trending of all utility services. There is truth in the statement, “what gets measured, gets managed.”
CSE: How do you balance the need for reliable power with the desire for efficiency and sustainability?
Karnatz: We believe that efficiency, sustainability, and reliability is the three-legged stool of power delivery in an office environment. Depending on tenant enterprise needs, the weighting of the importance of these three elements will vary.
Cooper: Step one is to understand the level of reliability required by the owner. A computer facility may, for example, have a different need than a general office environment. Once understood, we can then properly evaluate and design power system selective coordination such that impact to system efficiency or sustainability is minimized. The goal is to provide what’s needed in the most efficient way possible.
CSE: What type of backup or standby power systems have you specified into an office building recently?
Cooper: Most recently, we have installed parallel natural gas generators (N+1) with rotary UPS systems for critical electrical loads. As our reliance on information technology, Web-based communications, and data management continues to increase, the focus on robust electrical systems and reliable backup provisions will likewise increase.
Karnatz: We commonly provide backup and standby power through the use of multiple utility feeds, supplementary power generation, and UPS systems.