When power is on the line, it is critical that reliable energy delivery meet the needs of the community it serves — both functionally and in project execution. For utilities providing electricity in urban areas, gas-insulated substations (GIS) are often the right fit due to their advantages in space requirements, aesthetics and reliability.

A GIS project can typically reduce the necessary substation footprint to less than 25% of the equivalent air-insulated substation (AIS) size, especially if it requires a large number of interconnected circuits. This condensed footprint is especially important when land is scarce or costly, as is often the case in densely populated areas. GIS facilities enable utilities to develop functional substations where they are needed most, without significant space constraints or aesthetic roadblocks.

Compared to its AIS counterpart constructed in an open space with potential negative viewshed impacts, a GIS can be completely enclosed in a variety of building types, from insulated preengineered structures to architecturally interesting precast concrete. Buildings can be architecturally designed to add value to the neighborhood and overcome challenging terrain by using basements and retaining walls.

GIS projects may be the right approach for utilities even without space constraints. Utilities often consider GIS arrangements when brownfield sites need an upgrade or expansion, outage restrictions are an obstacle, restrictive transmission line entrance locations to the site exist, or if the site is exposed to extreme natural conditions, such as heat, cold or sand. By keeping equipment and systems from being exposed to natural elements, a GIS facility offers increased reliability, longer life expectancy and ease of maintenance, ultimately reducing operating costs.

As beneficial as GIS facilities can be, they are equally as complex to execute. The success of a GIS project hinges on close coordination between the substation design and building design teams. Closely coordinated interdisciplinary engineering helps see that interface points are designed appropriately and that permitting and other regulatory hurdles are met.

The engineer-procure-construct (EPC) method encourages early and constant collaboration between the owner and the qualified EPC contractor. Utilities can benefit from a turnkey project delivery method that meets the multidisciplinary demands of a GIS project — from engineering, design, permitting, varied procurement and construction scopes, which culminate in testing and commissioning of a final facility. Not only can the EPC approach offer a single point of accountability for cost and schedule certainty, utilities are able to leverage an experienced EPC contractor’s knowledge in areas where they may not have an abundance of experience, such as building design and construction or its interfaces with the substation equipment.

An EPC approach allows for parallel scoping iterations, advanced permitting considerations, preliminary design of electrical component and building interfaces, early engagement of major equipment suppliers, and construction planning activities, ultimately cutting months from the typical project cycle. The efficiency of an integrated team leverages the owner’s staff and their available time to manage the project.

When a GIS facility is the right fit for a utility, it should seek to partner with knowledgeable and experienced industry professionals who can successfully mitigate risks and effectively deliver these complex projects.


As urban populations grow, GIS facilities are helping utilities increase distribution system capacity and reliability despite limited available real estate. 

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Brad Davis is a department manager at Burns & McDonnell, where he leads an office in Baltimore and helps electric and gas customers achieve project success from concept to completion. He is experienced in building and leading teams and working on change management initiatives to help clients meet their goals. He specializes in technical consulting, power systems engineering, utility operations, strategic planning, program management and portfolio management.