Total Cost of Ownership: SF₆ GIS vs SF₆-Free Dry-Air GIS

When utilities, EPCs, and industrial operators compare medium-voltage (MV) gas-insulated switchgear (GIS), the discussion often starts — and sometimesends — with purchase price. However, MV switchgear is typically operatedfor 30 to 40 years, and many of the most significant costs occur after installation.

This is where Total Cost of Ownership (TCO) becomes the relevant metric. TCO captures not only the upfront investment, but also the long-term costsassociated with operation, maintenance, compliance, risk, and end-of-lifehandling.

This article compares the TCO of conventional SF₆ GIS with SF₆-freedry-air GIS, and explains how while upfront costs between SF₆ and SF₆-free GIS are broadly comparable, lifecycle analysis shows that SF₆-free dry-air GIStypically delivers 20–30% lower total cost of ownership over a 30-year servicelife, driven by the elimination of gas management, compliance, disposal, and risk-related costs.

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1. WhatIs Total Cost of Ownership (TCO)?

TCO considers all costs incurred over the full lifetime of an asset, including:

• Capital expenditure (CAPEX)
• Installation and commissioning
• Operation and maintenance  (OPEX)
• Regulatory compliance and reporting
• Risk and contingency costs
• End-of-life handling and disposal

For MV switchgear with long service lives, OPEX and risk-related costs often exceedthe initial purchase price.

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2.CAPEX: Purchase Price and Installation

SF₆ GIS

Historically,SF₆ GIS has benefited from:

• Long industrial maturityH
• Highly compact designs
• Highly compact designs
• Established supplier base

This oftentranslates into competitive upfront pricing, especially for standardised projects.

However, installation typically includes:

• Gas filling and density checks
• Certified SF₆ handling personnel
• Documentation for gas inventories

SF₆-FreeDry-Air GIS

Moderndry-air GIS:

• Matches SF₆ GIS in footprint and functionality
• Uses vacuum interrupters and air insulation
• Operates at neat-atmospheric pressure

Installation is simpler

• No gas filling procedures
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• No special gas handling equipment

Reduced commissioning  complexity

CAPEXdifference today is often marginal— and decreasing as SF₆-free adoption scales.

3.Operational Costs During Service Life

3.1 GasManagement and Monitoring

SF₆ GIS

• Continuous gas density     monitoring
• Alarm thresholds and     interlocks
• Periodic leak checks
• Inventory tracking and     reporting

SF₆-FreeDry-Air GIS

• No greenhouse gas management
• No density monitoring required
• No regulatory gas reporting

Overdecades, these activities translate into measurable recurring costs forSF₆ GIS that simply do not exist for dry-air systems.

3.2Maintenance and Personnel Requirements

SF₆ GIS

• Certified SF₆ technicians     required
• Special PPE during     interventions
• Decontamination procedures     after faults
• Higher training and safety     overhead

SF₆-FreeDry-Air GIS

• Standard electrical     maintenance procedures
• No toxic arc by-products
• Lower safety complexity

Thisreduces both direct maintenance cost and indirect organisationaloverhead.

4.Regulatory and Compliance Costs

Regulatorypressure on SF₆ continues to increase globally.

SF₆ GIS

Operatorsface:

• Mandatory gas inventories
• Leakage reporting
• Compliance audits
• Potential carbon pricing     exposure
• Future retrofit or replacement     risk

Thesecosts are difficult to predict — and tend to increase over time, notdecrease.

SF₆-FreeDry-Air GIS

• No F-gas reporting
• No GWP exposure
• Lower regulatory uncertainty

From a TCOperspective, regulatory risk is a real cost, even if it does not appearon a purchase order.

5.Risk-Related Costs: Failures, Outages, and Liability

Internalfaults and arc events

SF₆ GIS

• Arc decomposition creates     toxic and corrosive by-products
• Extended downtime for clean-up
• Specialist intervention     required
• Higher occupational safety     risk

SF₆-FreeDry-Air GIS

• No toxic decomposition     products
• Faster return to service
• Lower clean-up and liability     costs

Even rareevents have disproportionate economic impact, especially in urban orindustrial substations.

6.End-of-Life Costs: A Major Hidden Differentiator

SF₆ GIS

End-of-lifehandling involves:

• Certified gas recovery
• Transport of hazardous gas
• Storage or destruction at     specialised facilities
• Residual emission risk

SF₆disposal is technically complex and expensive, and in many cases gas isstored or reused rather than definitively destroyed — creating long-termliability.

SF₆-FreeDry-Air GIS

• No greenhouse gas recovery     required
• Standard dismantling     procedures
• No disposal-related climate     risk

From a TCOperspective, end-of-life costs alone can offset any initial CAPEX advantageof SF₆ GIS.

7.Comparative TCO Overview

Cost   Category

SF₆   GIS

SF₆-Free   Dry-Air GIS

Purchase  price

Comparable

Comparable

Installation

Higher  complexity

Simpler

Gas  management

Continuous

None

Maintenance

Higher

Lower

Regulatory  compliance

Increasing

Minimal

Risk  & liability

Higher

Lower

End-of-life

Complex  & costly

Simple

Long-term  cost certainty

Low

High

8. WhyTCO Is Becoming the Decisive Metric

As gridsexpand to integrate renewables, data centres, EV charging, and electrifiedindustry, utilities are deploying more MV switchgear than ever before.Small per-asset cost differences therefore scale rapidly at fleet level.

In thiscontext:

• Technologies with lower     uncertainty
• Fewer regulatory dependencies
• Simpler operation

deliversuperior long-term economics — even if upfront pricing is similar.

9.Conclusion

While SF₆GIS has historically been selected based on compactness and familiarity, its totalcost of ownership tells a different story when viewed over the full assetlifetime.

SF₆-freedry-air GIS typically delivers 20–30% lower total cost of ownership over a30-year service life because of the following:

• The elimination of gas     management and disposal costs
• A reduction of maintenance and     safety overhead
• The avoidance of long-term     regulatory and climate risk
• Greater cost certainty over     30–40 years

Whenevaluated on TCO rather than purchase price alone, SF₆-free GIS increasinglyrepresents the economically superior choice for modern MV networks.

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