Net zero - How to take the path to net zero carbon buildings

The whitepaper titled "Net Zero: How to take the path to net zero carbon buildings" was published in 2023 by Implenia, a leading international construction and real estate services provider based in Switzerland. Implenia aims to contribute to a sustainable real estate industry and assist in meeting climate targets through practical guidance on developing net zero carbon buildings. The foreword is penned by Marc Lyon, Head of Real Estate Development Switzerland at Implenia, highlighting the company's commitment to advancing sustainability in construction.

The primary audience for this whitepaper includes real estate developers, builders, architects, engineers, sustainability experts, policymakers, and other stakeholders involved in the real estate sector across Europe. This diverse group is essential for implementing the strategies outlined in the paper to achieve net zero carbon buildings.

Buildings are responsible for approximately 40% of global energy consumption and 36% of greenhouse gas emissions. Therefore, decarbonizing the building sector is vital for achieving climate objectives. Net zero carbon buildings are characterized by very low operational emissions from energy use, minimal embodied emissions from construction materials, and the offsetting of any residual emissions. Typically, these buildings incorporate high energy efficiency, renewable energy systems such as solar photovoltaic (PV) panels, and a significant proportion of low-carbon construction materials.

The whitepaper emphasizes that most emissions stem from materials and construction (referred to as upfront embodied carbon), which accounts for about 70-75% of total lifecycle emissions, rather than operational energy use. To tackle this issue, key strategies include efficient design, the use of renewable energy, passive design techniques, low-carbon materials, and effective offsets.

Decarbonization efforts should begin early in the construction process, starting with site selection. Factors such as compact building design, orientation, and glazing can significantly affect emissions. Establishing benchmarks is crucial for assessing a building's performance regarding embodied and operational carbon, with more ambitious targets needed to achieve net zero.

The paper highlights that the most effective opportunities for reducing carbon emissions lie in the initial planning and design stages. It advocates for a comprehensive approach that combines multiple strategies throughout the lifecycle of a building, as no single solution will suffice to reach net zero.

On-site renewable energy generation, particularly through photovoltaic systems, is essential for achieving net zero operational carbon. Optimizing factors such as orientation, tilt angle, and energy storage enhances self-consumption. Additionally, purchasing 100% renewable electricity can further diminish operational carbon emissions, with green leases facilitating access to renewable energy supplies.

The paper notes that natural shading, ventilation, thermal mass, and green roofs or facades can passively reduce cooling loads and mitigate the urban heat island effect.

Implenia has set ambitious targets for its projects, aiming for net zero operational carbon by 2030 for new builds and 2050 for refurbishments, while aspiring for net zero embodied carbon by 2040 for new constructions. Achieving these goals requires a combination of strategies applied across all lifecycle phases, emphasizing that a proactive approach during planning yields the most significant impact.

In summary, this whitepaper makes a compelling case for net zero carbon buildings, offering practical guidance based on lifecycle assessment and real projects to help the European real estate sector reduce its climate impact.