Designing flexible, complex office buildings: Electrical, power, and lighting
Mixed-use office buildings demand a great deal of expertise, flexibility, and complex technology, making them more challenging than one might expect. Engineers with experience handling office buildings share advice and a glimpse into the future regarding electrical, power, and lighting.
Jason Gerke, PE, CxA, LEED AP BD+C, Mechanical & Plumbing Group Leader |, Principal, Graef, Milwaukee
Jason Majerus, PE, CEM, LEED AP, Senior Engineering Leader | Principal, DLR Group, Cleveland
Pui-Yee So, PE, LEED Green Associate, Electrical Engineer, Design Team Lead, Page, Austin, Texas
John Yoon, Lead Electrical Engineer, McGuire Engineers Inc. (MEPC), Chicago
CSE: What are some key differences in electrical, lighting, and power systems you might incorporate in an office building, as compared with other projects?
So: Key differences include the fact that systems need to be flexible to accommodate future needs of the space, and there is an increasing need for the occupants to have control of lighting systems. There is also more of an emphasis on building occupants’ well-being. An example of flexible electrical systems is the power design bringing power to multipurpose rooms within office buildings that can be configured in multiple furniture arrangements. The power connections within the floor need to be flexible enough or placed in strategic locations for different furniture layouts. The lighting control system needs to be configurable and flexible to adapt to the different furniture layouts, different room uses (such as a presentation mode or lecture mode), and in some cases, different room partitions.
Majerus: Many companies are eager to define their own version of the Google work environment. This is critical for recruiting and staff retention. Creating that inspirational, signature environment often means implementing cool, modern, and creative lighting solutions.
Yoon: In multitenant buildings, product-selection criteria is often directly impacted by the terms of the lease. The landlord’s build-out allowance for a longer-term lease is usually more generous. With that larger construction budget, a tenant with a 10-year lease will usually be more motivated to invest in systems that focus on wellness and sustainability than one with a shorter 5-year lease.
CSE: How does your team work with the architect, owner, and other project team members so the electrical/power systems are flexible and sustainable?
So: We are an integrated engineering and architectural firm. We work together as a unified team to provide the owner with systems that are flexible and sustainable. One of the ways we do this is by having programming meetings with the owner early on in the project to determine the desired functionality of the space as well as which areas need to remain flexible for the future. We also have sustainability charrettes where the sustainability goals of the project are determined, such as WELL. Being in the same company allows us to best coordinate between disciplines and systems for a more efficient, coordinated design. Our collaborative process is enhanced by the use of BIM.
CSE: Describe a facility metering or submetering project. What did it include, and what best practices did you include for these facilities?
So: To meet LEED and new energy codes’ advanced-metering credit requirements, we added additional submeters to meter the systems, which individually contribute to more than 10% of the energy consumption of the building. We tried to keep the major mechanical equipment on the same panels to avoid adding many individual branch-circuit meters and to save cost. The lighting circuits were also metered either through metering the entire panel or the individual branch circuits where the panels also served other loads or equipment.
CSE: Are you seeing more smart grid or microgrid aspects on such projects? If so, how have you served these needs?
Yoon: No, although they offer the potential for increased grid resiliency, true microgrid (interconnected DES/DEG) installations in the Midwest are still rare. The primary barriers are funding and regulatory hurdles. For example, I’m aware of attempts to attach funding provisions for pilot microgrid projects in Illinois to electrical utility-rate case legislation, but none of those have been particularly successful. Usually, such provisions get scaled back significantly, or negotiated out, as part of the deal-making process involved with getting the overall utility-rate cases to pass the state house. Local electrical utilities in this area have created numerous artificial barriers to grid interconnection by third parties. It is not unusual for the amount of time required in a utility company engineering study to kill a third-party interconnection project. These types of barriers make it difficult for anyone other than the utility company to implement any type of small-scale DES/DEG program. And there is little motivation for any utility company that makes money off of infrastructure investment on a “cost-plus” basis to make the process easier. Most likely, DES/DEG won’t become significant in this area until the electrical-rate structures are significantly revised. Then, the DES/DEG requirement may be relaxed as a concession to allow passage of a bigger item, such as a demand-based rate structure.
So: We are seeing more microgrid aspects on projects. It is also common in new buildings to provide infrastructure rough-ins (space in the switchboard, physical space in rooms and in the building, conduit pathways) for future implementation. A recent project we worked on was a microgrid feasibility study for an existing building where we analyzed the financial and physical feasibility of adding a cogeneration system, Solar PV system, and battery-storage system. We also provided recommendations on which systems make sense for the building. The owner quickly adopted the recommendations and moved into the design phase of the project.
CSE: Are there any issues unique to designing electrical systems for these types of facilities? Please describe.
So: The flexibility of electrical systems, physical space, and metering are unique issues to designing office buildings. The electrical systems (power and lighting/lighting controls) need to be flexible to configure to different setups and tenant needs. As mentioned before, with the increase of sustainability initiatives, the physical space required for electrical equipment has increased. The metering between different tenants and what is considered to be part of the “building core” vs. a tenant space is also a challenge. Additional electrical equipment, such as entire panels or additional meters, need to be taken into account in conjunction with the owner/landlord’s rental-agreement contracts. Also, this can be tricky for mechanical HVAC equipment when one unit serves multiple tenants. It can lead to added cost and physical space if the HVAC equipment needs to be completely separate.
CSE: What types of unusual standby, emergency, or backup power systems have you specified for such facilities? What were the project goals?
So: In the past, an emergency power system for office buildings has only been provided for code requirements to power emergency egress lighting, firefighter elevators, fire alarm systems, and fire-suppression systems. More recently, more owners have requested other systems, such as their IT infrastructure and workstations, to be on backup power. On one of our recent projects, the program called for some critical office IT infrastructure to be operational at all times. We specified a central UPS system with battery backup fed from an emergency generator to feed the central IT servers.
Yoon: Data centers were usually the primary motivation for installing backup power systems in commercial office buildings. Once upon a time, most large corporate headquarters projects also had an enterprise data center as part of their scope of work. However, the number of large onsite data centers has decreased dramatically over the past several years. This corresponds with an industrywide trend toward remote colocation and cloud computing. With those mission critical functions now offsite, design considerations often don’t go much beyond basic NFPA 70: National Electrical Code (NEC), Article 700, compliance. This aside, new requirements in the 2018 edition of the NEC—such as provisions for a temporary generator connection, SPDs, what “fully coordinated” means, etc.—are a bit of challenge as authorities having jurisdiction are inconsistent in code interpretation for those.
CSE: What are some of the challenges when designing electrical, power, and lighting for office building projects?
Majerus: Today’s energy codes are becoming more complex with very specific functional and performance requirements for lighting controls. Whether it’s automatic time-of-day controls, daylight harvesting, or individual space-dimming controls for user comfort, these systems can initially seem more complicated or unnecessary to tenants who are not accustomed to them. It is important to provide training on these systems to ensure the occupants understand the functionality and are ultimately more satisfied with the outcome of the installation.
So: Challenges of designing electrical systems for office buildings include keeping power systems flexible for future modifications and balancing end-user lighting controls against how the overall building program is intended to function. Also, as mentioned before, getting space for electrical panels and control panels for lighting space.
Yoon: Multitenant office building projects are often speculative in nature. As opposed to a build-to-suit project, “spec” buildings need to be flexible enough to accommodate multiple different types of tenants, meet vague requirements for MEP infrastructure capacity based on boilerplate leasing requirements put forth by real estate brokers who have limited engineering knowledge, and yet still be cost-effective. Location, cost, and amenities typically are emphasized first by brokers, but in a competitive market, providing modern MEP systems can often be a tie-breaker. Tenant concerns regarding MEP systems often revolve around their ability (or lack thereof) to directly control their environment. All other things being equal, buildings that offer tenants more control over lighting and HVAC are typically perceived as being more desirable.
CSE: What kind of lighting designs have you incorporated into such a project, either for energy efficiency or to increase the occupant’s experience? Discuss the use of LEDs or other updated light sources.
So: On most of our projects, we use LEDs for energy efficiency. LEDs’ unique compact size also allows for new creative aesthetics for lighting manufacturers. The flexibility of using LED lighting allows the design team to configure lights to fit almost any space. LED technology also allows the creative use of color-changing decorative applications, and in some cases, the color temperature of white light can change throughout the day to match the daylighting outside to improve occupant circadian rhythms. Since the majority of LED lights comes with standard 0- to 10-V dimming drivers, it has also become more cost-effective to incorporate dimming into the lighting controls. This allows the occupants to adjust lighting levels to their desired levels and increase their experience.
Yoon: Most of the current buzz in lighting design centers is on tunable white lighting. Clients who have familiarity with the ability of tunable white lighting to support/enable circadian rhythms want to try it. However, very few projects actually end up using it due to cost. It normally gets value-engineered out somewhere in the course of the design.
CSE: When designing lighting systems for these types of structures, what design factors are building owners asking for? Are there any particular technical advantages that are or need to be considered?
So: Flexibility and adaptability—lighting design that can be adapted to future changes in site layout. Functionality—meeting lighting levels for their required tasks as well as to meet code. Aesthetics—the lighting plays a big part in the “feel” of a space and should be part of the overall design of the space, rather than just for functional purposes. We try to use indirect light fixtures where practical, to reduce glare on computer screens. It also helps to create a more comfortable environment. Additionally, the color temperature of the lights specified makes a difference to the building occupants. LED lights are able to be shaped and molded to different surfaces and applications, which helps provide better lighting distribution and a more pleasant environment. Controllability—more lighting is being requested with dimming capabilities and lighting control systems that can be reprogrammed when the areas are reconfigured. LED lighting technology also allows mechanical engineers to take a lower heat load from the lights, which improves the energy efficiency of the building.