The real estate sector is undergoing a fundamental transition. Particularly in inner-city area developments, the bar is being set increasingly high. Developing “Paris Proof” – in line with the objectives of the Paris Climate Agreement – requires not only energy-efficient buildings, but an integrated approach to CO₂ emissions across the entire life cycle. In this context, scope 1, 2 and 3 emissions are no longer abstract definitions, but concrete control variables in the development process.

The Three Scopes as a Basis for Steering

The classification into scope 1, 2 and 3 emissions originates from the globally applied Greenhouse Gas Protocol and forms the standard for measuring and reporting greenhouse gas emissions.

• Scope 1 includes direct emissions from owned sources, such as gas consumption on construction sites or emissions from owned equipment.
• Scope 2 concerns indirect emissions from purchased energy, such as electricity for offices or construction sites.
• Scope 3 includes all other indirect emissions in the value chain, both upstream (e.g. production of construction materials) and downstream (use and demolition of buildings).

For project developers, scopes 1 and 2 are relatively manageable. However, these scopes represent only a small share of the total climate impact.

Scope 3: The Real Impact of Real Estate

In real estate development, the bulk of CO₂ emissions almost always lies within scope 3. Research shows that in construction and real estate projects, these emissions can account for 80 to as much as 95% of total emissions.

This is because the largest emissions do not arise from the use of office space or site cabins, but from:

• the production of materials such as concrete, steel and glass
• transport and logistics within the value chain
• the energy use of buildings during their lifetime
• maintenance, renovation and eventual demolition

This means that choices in design, material use and supply chain collaboration largely determine the actual climate impact.

Paris Proof Development: A Shift in Focus

The ambition to develop Paris Proof is accelerating this shift. Whereas traditional sustainability strategies often focused on energy performance (e.g. EPC or BENG), the focus is shifting towards whole life carbon: total emissions over a building’s entire lifespan.

This has direct implications for the role of the developer:

• from optimizing building systems to optimizing material use
• from individual performance to supply chain responsibility
• from cost-driven design decisions to CO₂-driven decisions

In inner-city contexts – with limited space, high density and complex logistics – this challenge becomes even greater.

Why Scope 3 Is So Complex

The complexity of scope 3 mainly lies in three factors:

1. Lack of data and transparency
   Measuring scope 3 emissions is significantly more difficult than scopes 1 and 2. Data on materials, suppliers and usage phases is often fragmented or unavailable.
2. Limited direct influence
   These emissions fall outside the developer’s direct operational control. They arise from suppliers, contractors and end users, making control indirect.
3. Supply chain collaboration as a prerequisite
   Reducing scope 3 emissions requires intensive collaboration across the entire value chain. This calls for new contract forms, transparency and shared objectives – something that has not traditionally been standard in the construction sector.

Implications for Developers

For project developers, this means that the greatest sustainability challenge no longer lies within their own operations, but within the value chain. At the same time, scope 3 offers the greatest potential for emission reduction.

Concrete implications include:

• steering material choices: applying biobased or circular materials
• designing for disassembly and reuse
• collaborating with suppliers on CO₂ data and reduction targets
• integrating life cycle assessments (LCA) into the design process

In Paris Proof projects, this is reflected in choices such as timber construction, low MPG scores and minimizing transport movements within cities.

Conclusion

While scope 1 and 2 emissions represent the “low-hanging fruit,” the real challenge – and impact – lies in scope 3. This is where the largest emission flows are found, but also the greatest uncertainties and dependencies.

For project developers, this implies a fundamental shift in role and responsibility: from executor to supply chain orchestrator. Reducing scope 3 emissions is not only the greatest challenge, but also the key to achieving real climate impact.