Energy Performance Certificates (EPCs) evaluate a building’s energy efficiency and provide guidance for improvements. In complex multi-storey buildings, air leakage can have a significant impact on energy consumption and EPC ratings. Understanding and mitigating these leaks is essential for accurate energy assessment and sustainable building management.
What Is Air Leakage?
Air leakage occurs when uncontrolled gaps or openings in a building envelope allow warm or cool air to escape, increasing heating or cooling demand. Common causes in multi-storey buildings include:
Poorly sealed windows and doors
Gaps around pipe penetrations and service ducts
Faulty or aged insulation
Structural connections between floors and external walls
In high-rise or multi-unit buildings, air leakage can compound across multiple floors, resulting in substantial energy inefficiencies.
Why Air Leakage Matters for EPCs
Increased Energy Demand – Escaping air forces HVAC systems to work harder, increasing energy use.
Reduced EPC Ratings – Standard EPC assessments account for building envelope efficiency; significant air leakage can lower ratings.
Occupant Comfort – Drafts and temperature variations affect comfort and usability.
Regulatory Compliance – Ensuring airtightness may be required for certain building regulations or sustainability certifications.
For professional assessment of multi-storey buildings, check our EPC Assessors in London page.
Challenges in Multi-Storey Buildings
Complex Geometry – Numerous façades, roof levels, and junctions make airtightness testing more difficult.
Shared Systems – Multi-unit HVAC and ducting can create unintentional air pathways between units.
Accessibility – Inspecting higher floors, roofs, or hidden cavities may require specialized equipment.
Dynamic Occupancy – Variable use patterns can affect pressure differences and airflow, complicating measurements.
Methods to Detect and Mitigate Air Leakage
Blower Door Tests – Measure the airtightness of individual units or entire floors.
Thermal Imaging – Identify hidden leaks by visualizing heat loss.
Sealant and Insulation Upgrades – Target gaps around windows, doors, ducts, and structural penetrations.
Pressure Testing for HVAC Systems – Ensure ductwork is properly sealed to prevent cross-unit leakage.
Learn more about scheduling a professional assessment by booking your EPC inspection here.
Benefits of Controlling Air Leakage
Improved EPC Ratings – Airtight buildings score higher on energy performance.
Lower Energy Bills – Reduced heating and cooling demands.
Enhanced Comfort – More consistent indoor temperatures.
Sustainability Compliance – Supports carbon reduction goals and regulatory standards.
For guidance on pricing and assessment options, see our Pricing page or Contact Us for details.
Conclusion
Air leakage in complex multi-storey buildings is a critical factor affecting EPC ratings, energy efficiency, and occupant comfort. Accurate identification and mitigation of leaks, using methods like thermal imaging, blower door testing, and proper sealing, ensure reliable EPC assessments and support sustainable building operation.
