Development of National Guidelines for Improvement of Building Envelopes Airtightness Measures

Abstract

Airtightness of the building envelope is critical for reducing energy use, limiting convective moisture transport, improving indoor air quality and safeguarding the durability of building components. Despite two decades of regulatory airtightness requirements in Estonia, the absence of coherent national guidance has led to inconsistent on-site results and frequent underperformance relative to design assumptions. The new standard prEVS 946:2025 Guidance for improvement of building-envelope airtightness measures addresses this gap through an action-research process involving cyclic literature review, field measurements and stakeholder feedback. The standard introduces a process-oriented framework covering both new construction and renovation: it assigns clear responsibilities to a client-appointed airtightness specialist and a planner-side specialist and establishes mandatory phase-based deliverables from the project brief through intermediate blower-door testing to final verification in accordance with ISO 9972. The standard includes a large collection of illustrated examples of good and bad practice, covering material selection, junction detailing, installation quality and common failure modes. Field measurements in newly completed apartment buildings confirm that leakage is systematic rather than random, concentrated at window and door junctions, balcony connections, service penetrations and roof–wall interfaces, however object-specific other failures can occur. Measurements tracking one construction company over five years with recorded values between 0.67 and 1.45 m3/(h·m2) demonstrate that a systematic approach yields steady airtightness improvement. The selected central performance criterion for air permeability at qE50 ≤ 1 m3/(h·m2) for new energy-efficient buildings, balance ambition with practicality: they are stringent enough to deliver measurable energy and moisture-safety benefits while remaining achievable with coordinated practice.