Offices change, accommodating electrical and power requirements
To appeal to various clients and work styles, office building electrical system design is shifting
Office building insights
- Office building electrical system design is changing as owners and tenants expect more, especially flexibility.
- Electrification, smart lighting and flexibility are key for electrical systems in an office space.
- Miles Brugh, PE, Project Electrical Engineer/Manager, ESD, Chicago
- Adrian Gray, C Eng, Eur Ing, Global Director – Commercial and Real Estate Sector, HDR, London
- Matt Humphries, Associate Principal, Arup, Toronto
- John Yoon, PE, LEED AP, Principal Engineer, McGuire Engineers Inc., Chicago
What are some key differences in electrical, lighting and power systems you might incorporate in an office building, compared to other projects?
Miles Brugh: When it comes to office buildings, we enjoy the opportunity to design the electrical infrastructure as a blank slate. This makes it imperative to fully understand what the developer is looking to do. Office buildings typically are not designed around a specific tenant, so providing the best flexibility in the system is important. The flexibility opens opportunities with the leasing teams to be more aggressive with tenants that do have higher than normal requirements. Many times, larger tenants are looking to provide more amenity space that require more capacity, such as kitchens. This flexibility in the system can make the building more attractive for those types of tenants.
John Yoon: In multitenant commercial office building construction, the term of a lease (typically five or 10 years) strongly influences the cost and complexity of the systems that we specify. As a result, our designs often anticipate that those system will be changed and/or replaced after that initial lease period expires.
Adrian Gray: The key difference for office buildings’ systems is the requirement to be flexible to accommodate a variety of user groups, compared to other buildings such as schools, hotels or hospitals.
How does your team work with the architect, owner and other project team members so the electrical/power systems are flexible and sustainable?
Miles Brugh: There has been a larger push on projects to offset the resulting carbon footprint. The main ways we are seeing this addressed on the electrical side is adding a renewable energy component to the project. This is often accomplished using either a small on-site solar photovoltaic installation or via a power purchase agreement that allows them to purchase off-site renewables to help offset their consumption. Whether it is a new project or existing building either approach can be used to meet some of these goals.
Adrian Gray: Ensure the electrical design makes allowance for adaptation over the life of the building and designing systems to be as efficient as feasibly possible. Some of the examples include allocation of spare connections in the main switchgear and rising busbars with space for additional tenant tap-off connections. We work with other design team members by ensuring there is sufficient space for equipment, accessible distribution routes and easily accessible electrical risers for the landlord and tenant to adapt the building.
John Yoon: The first goal is to educate our clients. More often than not, clients have little understand of code requirement for the systems that we specify and their associated pros/cons. Without that information, it’s unreasonable to expect them to develop coherent project requirements that we can develop a basis of design from.
Sophisticated lighting controls, holistic lighting and other techniques are often incorporated into design. What unique lighting systems are you working on in office buildings?
Adrian Gray: Circadian lighting controls — lighting that follows the human circadian rhythm. Lighting control system integrated with the building converged network systems, enabling interoperability with other building systems. Flexible, open protocol lighting control systems such as Casambi. Reduced lighting level Category A lighting with flexibility for tenant enhancements. This is an extremely efficient method of lighting speculative office spaces as it reduces wastage while supporting well-being.
Miles Brugh: Lighting controls are becoming more and more integrated, whether it is a central system or having controls built into the light fixtures themselves. With integrated central systems, it is providing end users the ability to have more flexibility and insight into their operations which can be adjusted based on usage. For the integrated controls within fixtures, it can look like just another added cost on top of the overall fixture cost.
However, when it comes to installation and operation, this can really end up providing the most flexible design with easier installation. This has allowed adjustments in the field and users to rezone their spaces as they readjust to accommodate the flexible working environments we are currently in.
John Yoon: A few years ago, I thought that tunable white LED lighting would be the next big thing for office occupancies. However, we only specified it on a handful of projects due to cost and requests for it have dropped off dramatically. While not necessarily unique, integration of automatic receptacle control into lighting control systems seem like a better bet to take hold given that it has now been incorporated into the 2021 IECC.
Are you seeing more smart grid or microgrid aspects on such projects? If so, how have you served these needs?
Miles Brugh: For ESD, studies around implementing solar PV within campuses to allow clients to meet their sustainability goals.
Adrian Gray: We have not seen this specifically on office projects, although smart grid and microgrids are being developed. Electricity suppliers are designing and building a smarter, more dynamic electricity network to meet a net zero future.
John Yoon: No. However, I expect that to change in the near future when ADR and DER requirements start to be incorporated into the energy code.
What types of unusual standby, emergency or backup power systems have you specified for such facilities? What were the project goals?
Adrian Gray: Although generators are still a popular choice for standby, emergency or backup power systems, some of the options include:
- Alternative utility power sources, usually supplied from an alternative substation to avoid single point of failure.
- Uninterruptible power supply or offline battery inverter — each provided with power autonomy by central batteries.
- Local batteries.
We have also discussed gas turbine generators, although not yet seen these implemented on office projects.
Power availability from the electrical network operator.
What are some of the challenges when designing electrical, power and lighting for office building projects?
John Yoon: The first challenge is controlling the complexity of the control systems that we design. For the ideal control system, an average person should be able to effectively operate it without significant technical knowledge. While we can easily specify the part and pieces that meet prevailing code and functionality requirements, it’s very easy for the end product to be effectively unusable because of its complexity. Oftentimes, proper commissioning and end-user training can overcome that issue. However, keeping the user interface as simple as possible can minimize those issues that arise from incomplete commissioning and/or training.
Miles Brugh: The most challenging thing when it comes to designing an office building is with the initial space planning. As the engineering team, we want to limit our distances from the loads and the amount of raceway we run through open space. In addition, we have some code limitations to work through. In the growing amenity spaces we are seeing, clients are looking to locate that central on the first few levels, which typically is the best location for large electrical spaces and utility rooms.
Adrian Gray: Ensuring there is sufficient space for electrical plant, risers and services distribution routes, particularly in London where space is a premium. Engineering standards constantly evolving. We usually see quite major changes to design midway through a design. Predicting the maximum electrical demand and annual electrical usage for buildings. Although there are plenty of benchmarks and standards, it is almost impossible to predict the actual buildings in use figures. Energy efficient targets for lighting products. We regularly receive “lighting design” from other members of the design team that base lighting layouts on aesthetics alone. This can be extremely challenging when that design team partner has no knowledge of technical lighting design.
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 light sources.
Adrian Gray: We regularly design lighting as efficient as feasibly possible as this is one of the key drivers for ensuring the building meets planning requirements and obtains the best LEED, WELL classifications possible. We are now starting to see lighting product average efficacy of around 130 luminaire lumens/circuit-watt. We are investigating circadian lighting on a regular basis, but still not seeing this as a common installation due to up front capital costs.
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?
Adrian Gray: Interesting question, as we have clients that are constructing buildings and those that are running and maintaining buildings. In no particular order:
- Look and feel — appearance of the light distribution in the space.
- Energy efficiency.
- Costs — capital and in-use.
- Aesthetics — what does the fixture look like.
- Any technical benefits — DALI.
- Compliance with standards and technical design criteria. Manufacturer customer service.