To verify the environmental performance and make sure that designers promote sustainable design practices, it is important to assess the entire lifecycle impact of a building. This approach helps ensure that construction choices contribute to environmental payback over time and guide the selection of eco-friendly building materials. 

What is a Life Cycle Assessment (LCA)? 

In the context of a Plus Energy Building, Life Cycle Assessment is a method to evaluate the environmental impacts of a building over its entire lifespan. It goes beyond just looking at the operational energy use and considers all stages of a building's existence, from the extraction of raw materials to the end-of-life disposal. 

It considers all the environmental impacts of a building: this includes the embodied carbon in the building materials, the energy used during construction, the operational energy use, and the eventual disposal or recycling of the building components. 

What contributes to a building’s carbon footprint? 

• Load-bearing and envelope elements significantly impact a building's carbon footprint, particularly in reinforced concrete frame structures, where they can account for up to 20% of total CO₂ equivalent emissions. 

• Timber-based frames may offer lower embodied carbon than reinforced concrete structures but require careful assessment of structural, energy, 
and architectural needs. 

• PV modules contribute significantly to embodied emissions due to the high carbon intensity of current production methods. Although future technologies may improve this, PV systems remain a critical factor in a building’s environmental footprint. 

• The solution sets developed in the Cultural-E project demonstrate a low Global Warming Potential (GWP), averaging below 
5 kgCO₂eq/m² per year over 30 years, across all geoclusters and building archetypes. High-rise buildings generally perform better environmentally, as they optimize resource use. 

What is the environmental payback? 

The chart below compares the payback periods of demo cases across four countries: the left chart reflects the specific national energy mixes, while the right chart uses the EU-averaged energy mix. 

Several factors influence the environmental payback: 


• Countries with higher carbon intensity in their energy mix (e.g., Italy, Germany) reach environmental payback earlier. 
• In countries like France and Norway, which rely on nuclear power or renewable energy, environmental payback does not occur over building life cycle. For example, Norway's subarctic climate limits local PV installations and Norway energy mix is characterized by a high share of hydropower production.
• PV systems contribute significantly to embodied impacts but also play a major role in achieving environmental payback. 
• Material choices, such as timber versus reinforce concrete, should balance structural, environmental, and economic factors. 

Designers and architects can make choices that contribute to a building's environmental payback, moving towards the goal of net-zero emissions.

Detailed guidelines for assessing a PEB's environmental impact are provided in the Guidelines and calculation methods for Lifecycle Environmental Impact Assessment of Plus Energy Buildings.