Low-Carbon Terminal Retrofit: Decarbonising Airports Without Starting Again

The aviation industry’s transition towards net zero is often discussed in terms of aircraft technology, sustainable aviation fuel and the electrification of ground operations.

However, airports must also address the carbon associated with the buildings they already operate.

Passenger terminals are complex, energy-intensive environments. They require heating, cooling, ventilation, lighting, baggage handling, security systems and digital infrastructure to operate for long hours—often continuously. Many existing terminals were designed when energy was cheaper, carbon targets were less demanding and passenger expectations were very different.

The response cannot always be to replace them.

Constructing a new terminal requires significant quantities of concrete, steel, glass and other carbon-intensive materials. It can also demand years of planning, major capital investment and extensive disruption to airport operations.

A low-carbon terminal retrofit offers another route: retaining the value already embodied within the building while progressively improving its environmental and operational performance.

Looking Beyond Operational Energy

Historically, airport decarbonisation has focused largely on the energy consumed while buildings are in use.

This remains essential. According to Airport Carbon Accreditation, airport-owned buildings, assets and ground vehicles are among the principal sources of the Scope 1 and Scope 2 emissions directly controlled by airport operators.

However, operational energy is only part of the picture.

A whole-life carbon assessment also considers the emissions associated with producing materials, constructing the building, replacing components, maintaining assets and eventually dismantling or disposing of them.

This embodied carbon can be significant.

Demolishing a structurally sound terminal and replacing it with a more energy-efficient building may reduce future operational emissions, but it creates a substantial upfront carbon cost. That cost must be understood alongside the savings achieved during operation.

The RICS Whole Life Carbon Assessment standard provides a consistent methodology for assessing both operational and embodied carbon across the life of an asset.

For airport operators, this means the question should not simply be:

How efficiently could a new terminal operate?

It should also be:

How much of the existing terminal can be retained, improved and used for longer?

Start With the Existing Building

Every low-carbon terminal retrofit should begin with a detailed understanding of the existing asset.

This includes analysing:

• Current energy consumption and seasonal demand

• The age and condition of mechanical and electrical systems

• Thermal performance and air leakage

• Solar gain through façades and rooflights

• Lighting performance and control

• Passenger occupancy patterns

• Baggage, security and operational equipment loads

• Opportunities to reuse existing structures and materials

This assessment helps distinguish between genuine building constraints and inefficient operation.

A terminal may consume excessive energy because its façade performs poorly. Alternatively, the problem may be outdated plant, unsuitable control settings or systems operating at full capacity during periods of low occupancy.

Without a reliable baseline, an airport risks investing in visible sustainability measures while overlooking the interventions capable of delivering the greatest reduction.

Retaining the Structure

The most important carbon-saving decision may be made before detailed design begins.

Existing terminal structures contain large quantities of concrete and steel. Where these remain safe, serviceable and adaptable, retaining them can avoid much of the upfront carbon associated with demolition and reconstruction.

Retention does not mean preserving every part of the building unchanged.

Floors may be opened to improve passenger circulation. Structural bays may be adapted for new processing equipment. Extensions may still be required where a clear operational need exists. However, the design should begin with the assumption that existing assets have value.

This approach also supports phased development. Rather than replacing an entire terminal around one long-term forecast, airports can upgrade individual areas as passenger demand, airline operations and technology evolve.

Improving the Building Fabric

Older terminals frequently lose energy through poorly insulated roofs, façades, doors and glazing.

Upgrading the building envelope can reduce heating and cooling demand, but terminal façades require careful treatment. Extensive glazing provides daylight, views and a sense of orientation, yet it can also create heat gain, glare and uncomfortable conditions near the perimeter.

The solution is rarely to remove transparency altogether.

High-performance glazing, solar-control coatings, improved seals, insulated opaque panels and external shading can significantly improve performance while retaining the architectural qualities of the terminal.

Automatic doors and entrance lobbies also deserve attention. Large numbers of passengers, baggage trolleys and staff move through terminal entrances throughout the day, creating repeated air loss. Better entrance configurations and controls can reduce this without impeding passenger flow or accessibility.

Replacing Services Strategically

Mechanical and electrical systems are often the greatest challenge—and the greatest opportunity—within a terminal retrofit.

Ageing boilers, chillers, ventilation plant and lighting systems may be inefficient, difficult to maintain or unable to respond accurately to demand. Replacing them can deliver substantial operational carbon savings, particularly when combined with improved controls and a transition away from fossil fuels.

Potential measures include:

• Heat pumps and low-temperature heating systems

• Heat recovery from ventilation and cooling systems

• Demand-led ventilation based on occupancy

• LED lighting with daylight and presence controls

• More efficient chillers and air-handling plant

• On-site renewable electricity generation

• Thermal or battery energy storage

• Intelligent building-management systems

However, services should not be designed independently of terminal operations.

A more efficient security process may change passenger occupancy within the building. New retail concessions may increase cooling and power demand. Common-use processing could reduce the number of fixed check-in positions while increasing requirements elsewhere.

Operational change, architectural design and energy strategy must therefore be modelled together.

Designing Around Variable Demand

Terminals do not operate at a constant level of occupancy.

Passenger numbers rise and fall according to flight schedules, seasonal demand and disruption. Yet many older systems treat the terminal as though every area is equally occupied throughout the day.

Zoning allows heating, cooling, lighting and ventilation to respond more closely to actual use.

Check-in zones can be activated around airline demand. Gate rooms can reduce energy use when unoccupied. Back-of-house facilities can operate independently from passenger spaces. Flexible boundaries can prevent large volumes of air being conditioned unnecessarily.

This is where passenger-flow modelling can support carbon reduction as well as capacity planning. By understanding when, where and for how long people occupy different spaces, airports can align environmental systems with real operational demand.

Reusing Materials and Designing for the Next Retrofit

A low-carbon retrofit should also reduce waste.

Existing stone flooring, ceiling systems, partitions, doors, furniture and architectural finishes may be suitable for retention or refurbishment. Where replacement is necessary, materials should be selected for durability, repairability and future reuse.

Demountable partitions, reversible fixings and accessible service zones make later changes easier. Components can be replaced without stripping out entire areas, while materials can be recovered rather than discarded.

This is particularly relevant to airports because terminals are never truly finished. Security requirements change. Airlines move. Retail offers are renewed. Technology is replaced. Passenger processes evolve.

Designing for disassembly helps ensure that today’s low-carbon retrofit does not become tomorrow’s waste-intensive strip-out.

Delivering Retrofit in a Live Airport

The environmental case for retrofit must be matched by a credible delivery strategy.

Airports cannot simply close a terminal while it is upgraded. Passenger processing, security, baggage operations, emergency routes and commercial activity must usually continue throughout the works.

This requires detailed planning around:

• Temporary passenger and staff routes

• Construction logistics and material storage

• Airside and landside segregation

• Dust, noise and vibration

• Fire and life-safety systems

• Temporary services

• Equipment changeovers

• Short operational possessions

• Seasonal passenger peaks

Phasing should be considered from the earliest design stage, not added after the preferred solution has been developed.

In some cases, a series of smaller interventions will produce a more practical and lower-risk route to decarbonisation than one comprehensive refurbishment. Plant can be replaced progressively, façade zones upgraded in sequence and internal spaces renewed alongside operational projects.

A Terminal With a Longer Life

Low-carbon terminal retrofit is not simply about installing efficient equipment.

It is about reconsidering the value of the existing building.

By retaining structures, improving façades, replacing services strategically, responding to real occupancy and designing future changes around reuse, airports can reduce carbon while improving comfort, resilience and operational performance.

New terminal infrastructure will sometimes be necessary. But it should follow a clear assessment of what the existing asset can still provide.

The lowest-carbon terminal may not be the newest.

It may be the one that has been intelligently adapted to remain useful for decades longer.