Emissions in Construction – Moving Towards More Precise Predictions with the ATP CO₂ Tool

Red emissions? Grey emissions? – What exactly is that?
In sustainability discussions, there is often talk of red and gray emissions. Operation-related 'red' emissions arise during the ongoing operation of a building, for example, through heating, ventilation, hot water preparation, or lighting. Material-related 'gray' emissions, on the other hand, occur during the production, transport, installation, maintenance, dismantling, and disposal of building materials.

Energy is a universal good: Whether a brick is produced in Germany, Brazil, or China, the energy demand is similar. The crucial difference lies in the type of energy source. For example, if green energy such as photovoltaics or hydro power is used, fewer emissions are produced than with fossil fuels like oil. Country-specific emission factors also play a role, strongly influenced by political decisions, such as the promotion of certain technologies.

The Challenge with CO₂-Analysis
With the Green Deal, the EU has taken an important step towards climate protection and sustainable construction. The Green Deal's guidelines define how operation-related emissions must be measured and calculated. This has led to better planning decisions: while around 70–75% of total emissions used to come from operations, today we have managed to reduce this to 30% of total emissions.

Established European standards have existed for operation-related emissions since the 1980s. However, it wasn't until 2012 that we were on the right path for material-related emissions with the introduction of the Environmental Product Declaration in the EU. Another issue: Underlying emission factors vary greatly by country and are politically influenced.

We have gained a lot of experience with operation-related emissions, so we can predict them well, even though politically motivated factors can still influence material choices. With material-related emissions, the situation is much more complex.

An average building consists of around 20,000 different materials. With each of these materials, we would need to examine exactly where it was produced, by whom it was supplied, and how it was processed. This is unrealistic. Therefore, we rely on databases with standardized values, being aware that these are often inaccurate and influenced by political factors in the calculation.

How can operational emissions be reduced?
To properly reduce energy and emissions, there are 4 steps:

A. First, passive measures such as window replacement or improving insulation can be taken.

B. Also, efficiency measures such as optimizing ventilation systems or replacing equipment contribute to the reduction.

C. Implementing on-site renewable energies such as photovoltaics or heat pumps is another step towards sustainability.

D. A fourth option is the use of off-site renewable energies such as building PV systems on another property or purchasing certificates.

With these A-B-C-D measures, buildings can be optimized today to significantly reduce energy consumption (the keyword being 'Nearly Zero Energy Building'). It is important to first reduce the operational demand and then only use renewable energies afterwards – the reverse approach does not work and contradicts gray, material-related emissions.

However, the situation with material-bound emissions is more complex. There are life cycle assessment tools available, but these require a lot of input data that is often not available in the early project phases. That is why at ATP, we have decided to develop our own CO₂ calculation tool to calculate the CO₂ balance of real projects as a differential life cycle assessment. This way, we can determine early on which materials have a high or low CO₂-Footprint and make informed decisions. The tool not only helps reduce CO₂ emissions but also provides valuable insights that can be used for future projects.

What is meant by a balance sheet framework?
To improve the comparability of CO₂ calculations, the balance sheet framework is crucial. In various standards, such as the OIB guidelines in Austria or the Building Energy Act (GEG) in Germany, the balance sheet framework for operation-related emissions is defined. For materials, this is specified in the relevant standards such as the life cycle calculation framework, which is set at 50 years – regardless of whether the material lasts longer or not.

The physical framework is also of great importance: What exactly is being accounted for? The entire building? Including the parking lot? This is crucial because asphalted parking areas often cause more emissions than the building itself.

In addition, there's the difficulty that we can't calculate all life cycle phases for materials: For example, we know too little about the emissions from the truck's transportation phase. This leads to a situation where, despite a standardized balance sheet framework, life cycle assessment data cannot always be precisely compared. Improved comparability is achieved only when the balance sheet framework and the balance sheet data are transparent and clearly defined. Only then can we understand which aspects were even calculated – and the differences can be drastic. It's not just about 2-3%, but sometimes up to 100%.

Conclusion and Outlook
Precise overall CO₂ accounting remains one of the major challenges in the construction industry. While we have already made significant progress with operational emissions, the accurate calculation of material-related emissions remains problematic. Achieving a more precise CO₂ accounting requires not only the development of better tools and standards but also enhanced collection and evaluation of relevant data. Only in this way can we ensure that the CO₂ emissions from buildings are sustainably reduced at all stages of their life cycle, and the construction industry can actively contribute to shaping a more climate-friendly future.