The challenge: Tall and super-tall buildings: Electrical and power systems
High-rise buildings aren’t just big—for engineers, they present big challenges. The electrical engineer has many distribution, metering, and power system issues to consider.
Jason Heffelmire, PE Gulf Coast operations director, TLC Engineering for Architecture, Tampa, Fla.
Mehdi Jalayerian, Executive vice president, Environmental Systems Design, Chicago, Ill.
Jim Quiter, PE, FSFPE, LEED AP, Principal, Arup, San Francisco, Calif.
CSE: Describe some recent electrical/power system challenges you encountered when designing a new building or working in an existing building.
Heffelmire: Determining the level of reliable power to provide for the various building occupancies and uses, and understanding the owner’s mind-set is always a challenge in new or existing buildings. Reliable power can be on-site generated, uninterrupted power supply (batteries), a dual utility service entrance, or any combination of the three.
CSE: How do you balance the need for reliable power with the desire for efficiency and sustainability?
Jalayerian: Extending the medium-voltage primary distribution to as close as possible to the load center reduces the material required to distribute power while also reducing distribution power losses. The zoning within these super-tall or high-rise buildings lends itself to configuration through multiple electrical feeds, which inherently increases the system reliability and redundancy. In this way, it is a similar concept to the horizontal distribution of cities, and as designers we can look at super-tall buildings as vertical cities.
Heffelmire: Reliable power is paramount and goes hand-in-hand with system efficiencies and sustainability. Balancing the need for reliable power with the desire for efficiency and sustainability can take several forms. For example, a photovoltaic system can be a redundant power source combined with on-site generators but must be balanced against overall project costs.
CSE: What low- and medium-voltage power challenges have you overcome?
Heffelmire: Some issues when specifying medium-voltage systems are whether the user has the ability to maintain the switchgear with its present staff or go to outside sources. In Florida, the return on investment on medium-voltage switchgear does not receive as attractive a utility company incentive as in other parts of the country.
CSE: Describe a recent tall/super-high-rise project in which you specified standby or emergency power. What challenges did you face, and how did you overcome them?
Heffelmire: Standby or emergency power system challenges usually deal more with mechanical issues like proper acoustical treatment of the area housing the equipment on a limited site, locating the muffler exhaust to not create a nuisance, and locating an adequate fuel storage facility.
CSE: What types of renewable energy systems have you recently specified in one of these projects?
Jalayerian: The headquarters for the Federation of Korean Industries, Seoul, South Korea, which opened to the public earlier this year, features integrated photovoltaic panels on its façade, which use alternating upward-angled spandrel panels to maximize sun exposure for energy collection and downward-angled viewing panels to minimize sun glare and heat gain, thereby reducing the cooling load. We performed an optimization analysis during design for the positioning and placement of these panels to support the maximum amount of energy that would be collected to generate power for the tower’s electrical systems. Certain portions of exterior wall spandrel panels were fitted with active photovoltaic panels to maximize performance and to increase economic benefit.
Heffelmire: Tall and super-high-rise buildings would be a great place for installing a photovoltaic system, but overcoming the high first cost is just one problem. As buildings get taller, the higher floors become more expensive to build and their floor plan becomes smaller because of light and air setbacks. Available roof space also diminishes. We have had some luck with geothermal systems, but only for small buildings. We looked at wind power for a high-rise, but controlling the noise of the blades was a big issue for surrounding areas.
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