In the push towards achieving sustainability and energy efficiency goals, retrofitting traditional buildings has become a priority. However, one of the most pervasive and overlooked challenges in retrofit projects is thermal bridging. Architects tasked with retrofitting historic or traditional buildings must understand how thermal bridges compromise energy performance and what solutions exist to address them effectively.
Retrofitting traditional buildings is crucial for improving energy efficiency and reducing carbon emissions. The government document Improving Energy Efficiency in Traditional Buildings highlights strategies for upgrading energy performance in historical structures, with special focus on addressing thermal bridging. Let’s look more closely at the driving forces and incentives for improving thermal bridging in the retrofit sector.
Understanding Thermal Bridging: A Technical Overview
Thermal bridging occurs when materials with high thermal conductivity, such as steel, timber, or masonry, allow heat to pass through the building envelope, bypassing insulation layers. In architectural terms, thermal bridges often emerge at junctions—where walls meet floors or roofs, around window openings, or at structural penetrations like balconies or service pipes. In these areas, the insulation layer can be compromised, leading to significant heat loss.
For traditional buildings, particularly those with solid masonry construction, thermal bridging poses a considerable risk. Unlike modern buildings that rely on cavity walls and vapour barriers, traditional structures manage moisture and heat through mass and permeability. When retrofitting, applying modern insulation techniques without addressing thermal bridges can not only result in energy inefficiencies but also exacerbate moisture problems, leading to condensation, mould, and long-term structural deterioration.
Why Thermal Bridging Must be Addressed
It’s critical to consider how even well-insulated buildings can experience substantial energy losses if thermal bridges are not adequately mitigated. Here’s why thermal bridging should be a priority in retrofit designs:
- Energy Loss and Inefficiency: Thermal bridges can account for up to 30% of the heat lost in a well-insulated building. This compromises the overall thermal performance of the retrofit, significantly increasing heating and cooling demands. Even small areas of unaddressed thermal bridging can negate the positive effects of extensive insulation upgrades.
- Condensation and Moisture Management: In traditional buildings, heat loss through thermal bridges can lead to surface cooling, increasing the risk of interstitial condensation. Over time, this can cause dampness, mould growth, and potential structural degradation. Proper moisture management is essential in retrofits, especially in historic buildings where preserving the building fabric is paramount.
- Regulatory Compliance and Energy Targets: Ireland’s Climate Action Plan mandates that 500,000 homes be upgraded to a B2 Building Energy Rating (BER) by 2030. Similarly, the UK’s Future Homes Standard and Minimum Energy Efficiency Standards (MEES) for rental properties require stringent energy performance. Thermal bridges, if left unaddressed, can prevent buildings from meeting these ambitious targets. Furthermore, with increasing demand for Nearly Zero Energy Buildings (NZEB), particularly in new builds, achieving high energy performance in retrofits is critical to comply with evolving standards.
- Aesthetic and Historical Preservation: Working on traditional and heritage buildings must balance energy performance upgrades with the preservation of the building’s architectural integrity. Poorly implemented insulation solutions can detract from a building’s historical character or lead to irreversible damage. Addressing thermal bridging with appropriate techniques ensures that the retrofit is both energy-efficient and sensitive to the building’s original design.
Modern Standards: Energy Performance in Ireland and the UK
To contextualise the importance of addressing thermal bridging, it’s crucial to examine the energy performance standards that architects must adhere to during retrofit projects.
Ireland’s Energy Regulations
Ireland’s Part L of the Building Regulations governs energy conservation in buildings, including retrofits. A core objective is upgrading the national building stock to achieve higher BERs, with the Climate Action Plan aiming for a 51% reduction in carbon emissions by 2030. To meet this, retrofitted buildings must incorporate advanced insulation techniques, airtightness, and energy-efficient systems, while addressing thermal bridging.
The transition to NZEB standards further highlights the importance of tackling thermal bridging. New dwellings must meet very high energy performance criteria, and retrofitted buildings must be insulated to a standard that reduces overall energy consumption to align with national goals.
The UK’s Energy Performance Standards
Similarly, in the UK, the Future Homes Standard mandates that all new homes by 2025 must produce 75-80% fewer carbon emissions than homes built to current standards. For existing buildings, the MEES require rental properties to meet a minimum EPC rating of C by 2025. Addressing thermal bridging in retrofits is not only necessary to meet these targets but also to future-proof the building against further regulatory changes as the push for net-zero carbon intensifies.
Technical Solutions for Thermal Bridging in Retrofits
Thermal bridging in retrofit projects requires specific design considerations to ensure energy efficiency is maximised without compromising the structural and aesthetic integrity of the building. The following solutions are critical for architects:
- Thermal Breaks: Introducing thermal breaks at junctions where different building elements meet (e.g., wall-floor, wall-roof junctions) is essential. These thermal breaks use materials with low thermal conductivity to prevent heat transfer. For traditional buildings, solutions must be carefully designed to ensure that these breaks do not affect the building’s visual character or structural integrity.
- Continuous Insulation Layers: To minimise thermal bridging, it’s beneficial to also include insulation systems that create continuous thermal layers, eliminating gaps where heat can escape. This can be achieved using internal or external insulation, depending on the building’s characteristics and heritage requirements. External insulation, while often effective, may not be appropriate for all traditional buildings and must be carefully assessed on a case-by-case basis.
- Use of High-Performance Thermal Bridging Blocks: Partel’s Alma Vert thermal bridging blocks are an ideal solution for architects addressing thermal bridges in retrofit projects. These blocks are specifically designed to mitigate heat loss at critical junctions, offering low thermal conductivity without compromising the structural performance. Integration of Alma Vert blocks into retrofit designs, can achieve seamless insulation continuity, improve energy performance, and reduce the risk of condensation and moisture problems.
- Sustainable Materials: Alma Vert blocks are made from eco-friendly, high-performance materials, aligning with the growing need for sustainable construction solutions in retrofits.
- Compatibility with Heritage Buildings: These blocks are especially suitable for retrofits of traditional or heritage buildings, offering a solution that maintains the integrity of the building while improving its thermal performance.
- Ease of Integration: With their structural strength and versatility, Alma Vert blocks are easy to integrate into a range of junction types, making them a practical choice for architects managing complex retrofit projects.
A Call for Architectural Precision
For architects involved in retrofitting traditional buildings, addressing thermal bridging is not just an optional enhancement but a necessity to achieve energy performance standards. Thermal bridges pose a significant risk to the integrity, comfort, and energy efficiency of retrofitted buildings. Partel can deliver projects that meet the stringent energy targets set by governments in Ireland and the United Kingdom while also preserving the unique character of traditional buildings by utilising modern solutions such as Alma Vert thermal bridging blocks.
The technical challenges posed by thermal bridging can be overcome with precise planning, careful design, and the right materials. Addressing these challenges proactively ensure that retrofit build projects not only comply with modern standards but also contribute to a more sustainable built environment.
