In Bielefeld, Germany, a family decided to bring their architect-designed home from 1965 up to modern energy standards.
The renovation focused primarily on the flat roof, which had become outdated and inefficient. By applying advanced insulation techniques and taking advantage of government subsidies, the project both improved thermal efficiency and extended the roof's lifespan.
This aligns with current European renovation goals on energy efficiency and serves as an interesting case to consider for broader application across the EU.
Outdated Flat Roofs and EU Climate Goals
Flat roofs, especially those constructed in the mid-20th century, often suffer from insufficient insulation and energy inefficiency. This was the case for this family’s home. Their biggest issue appeared in the cold roof construction being ventilated, allowing air to circulate freely, which led to high energy losses.
Such roofs fall short of today’s high energy performance standards, such as those defined by the Energy Performance of Buildings Directive (EPBD),which aim to achieve near-zero energy buildings in Europe by 2050.
Upgrading the building's flat roof posed a significant challenge, as sizeable structure changes were required to meet today’s insulation standards. Finally, the challenge was further heightened by the need to manage condensation risks without compromising the architectural integrity of the house.
Future-Proofing with Inverted Roof Insulation
The family opted for a complete replacement of the flat roof, converting it from a cold roof to an inverted roof system. This decision was driven by the advantages offered by such systems, including the protection of the waterproofing layer beneath the insulation, which increases the roof’s durability.
An inverted roof construction, where the insulation is placed above the waterproofing layer, provides excellent protection against weathering and thermal bridging, a common issue in flat roof designs. By using pressure-resistant insulation, the renovation achieved a high level of thermal efficiency, with a U-value of 0.14W/(m²K), well within the standards set by the KfW Development Bank, which subsidises energy-efficient renovations.
This solution aligns with EU goals to cut carbon emissions, as flat roofs have the potential to reduce household energy consumption significantly. According to the European Commission, energy-efficient roofs can save up to 30% in heating costs, which is a long-term solution as durable and low-maintenance materials were used in the renovation.
RenovationProcess and Insulation Techniques
The renovation was carried out by a team of roofing specialists, and despite the complexity of removing the old roof structure and installing the new one, the process was quick and effective. The 150-square-meter roof area was transformed into a 0° roof with improved drainage systems and thermal insulation installed in a single layer. Key steps in the implementation included:
QuantifiableEnergy Savings and Enhanced Comfort
The most immediate impact of the renovation was a significant reduction in energy consumption. The new flat roof now meets modern energy standards, contributing to a 30% reduction in heating costs for the homeowners. This aligns with data from the European Energy Agency, which suggests that properly insulated roofs can reduce overall building energy demand by as much as 25%.
Additional benefits include:
The project also had an impact on property value. Homes with modern energy-efficient features, particularly well-insulated roofs, tend to see a 5-10% increase in market value, a factor that will benefit the family should they decide to sell the property in the future.
SupportingEU Energy and Climate Objectives
The renovation of this home illustrates how small-scale residential projects can support broader European policy objectives. Under the Renovation Wave strategy, the EU aims to renovate 35 million buildings by 2030, reducing carbon emissions and improving energy efficiency across the continent.
This case demonstrates the importance of prioritising energy efficiency first, rather than relying solely on decarbonising energy supplies. By reducing energy demand through better insulation, such projects contribute to lowering Europe’s reliance on external energy imports, strengthening energy resilience.
Additionally, this approach supports the upcoming implementation of minimum energy performance standards (MEPS) under the EPBD, which will mandate energy upgrades for existing buildings by 2030.
As stakeholders work to meet these ambitious targets, focusing on cost-effective measures like flat roof insulation will help mitigate the risks associated with energy price fluctuations and rising energy bills. Properly insulated buildings also ease pressure on the electrical grid, reducing the need for costly energy infrastructure upgrades.
Scalabilityand European Impact
Flat roofs, commonly found in older European buildings, represent a scalable opportunity for improving energy efficiency across the continent. Projects like the one in Bielefeld demonstrate that renovating flat roofs can be done quickly, cost effectively, and with significant energy savings.
By leveraging available government subsidies and focusing on thermal insulation, other homeowners and building managers can replicate this success. As Europe moves toward its 2050 climate neutrality goals, similar renovation strategies will be essential in reducing carbon emissions and promoting sustainable development.
