What Is a Hygrothermal Perfromance Assessment?

A hygrothermal perfromance assessment is a simulation-based analysis that evaluates how heat and moisture interact within building materials and assemblies over time. Unlike obselete traditional dew point calculations with the Glaser method (BS EN ISO 13788), our hygrothermal modelling in accordance with BS EN 15026 considers:

• Transient climate conditions (e.g. real hourly weather data)
• Vapour diffusion, capillary movement, and liquid transport
• Material-specific properties, such as water absorption and drying behaviour
• Wind-driven rain, solar radiation, and indoor climate profiles

Using these inputs, we simulate how a wall, roof, or floor behaves over several years -tracking moisture content, temperature, and relative humidity throughout its layers to assess condensation risk, drying potential, mould growth risk, and material degradation.

Service Scope: What We Offer

Ecosophy Studio provides project-specific hygrothermal modelling and risk analysis using WUFI® Pro, and WUFI® 2D, depending on the complexity of the construction detail and intended outcome. Our services include:

• One-dimensional (1D) modelling of layered assemblies (e.g., external walls, pitched or flat roofs)
• Two-dimensional (2D) modelling of junctions and details where geometry impacts moisture movement (e.g., eaves, parapets, balconies)
• Assessment of moisture-related risks such as interstitial condensation, mould growth potential, timber degradation due to rot, reduced perfromance of insulation, etc.

• Evaluation of internal insulation strategies and external wall insulation strategies in traditional buildings and solid masonry walls.
• Analysis of piched roof insulation and flat roof insulation  
• Comparative modelling of proposed vs. optimised build-ups to support specification decisions.
• Support for PAS 2035, EnerPHit, or AECB CarbonLite retrofit design.

• Analysis of modern external wall systems (timber-framed, CLT, etc.).
• Analysis of new-built flat roofs, pitched roofs, and green roofs.
• Comparative modelling of proposed vs. optimised build-ups to support specification decisions.
• Support for Passive House and AECB CarbonLite New Build designs.

Applications in Product Development:

Furthermore, we support manufacturers and suppliers embarking on the introduction of new products and building systems into the market by bolstering their product launch through comprehensive parametric hygrothermal risk analyses supporting submissions towards a KIWA Certification, a BBA Certificate, or similar.

Deliverables include comprehensive reports, annotated graphs of moisture content, relative humidity, and temperature levels, with clear summaries of risk, performance, and design implications.

Regulatory and Standards-Based Compliance

Our hygrothermal assessments are aligned with the latest guidance and standards, including:

• BS EN 15026:2023 – Hygrothermal performance of building components and building elements – Assessment of moisture transfer by numerical simulation: This is the core standard for dynamic hygrothermal simulation in Europe and underpins the WUFI® calculation methodology.
• BS EN ISO 13788:2012 – Hygrothermal performance – Internal surface temperature to avoid critical surface humidity and interstitial condensation: While still used in basic condensation risk assessments, this standard’s steady-state method is often insufficient for evaluating modern, highly insulated build-ups—especially in retrofit scenarios. We use it for reference and in comparative assessments.
• BS 5250:2021 – Management of moisture in buildings: The updated BS 5250 highlights the importance of risk-based, dynamic moisture assessments for designs involving internal insulation or vapour-sensitive materials. It directly endorses the use of BS EN 15026 and tools such as WUFI for situations where traditional methods fall short.
• PAS 2035: For retrofit projects, our assessments help fulfil the moisture risk assessment requirements of PAS 2035 (2023), supporting Retrofit Coordinators in justifying material choices and mitigating unintended consequences.

We also ensure compatibility with Passive House Institute guidelines, for projects aiming at Passive House and EnerPHit certification, as needed.

Why Choose a Moisture Risk Assessment with WUFI®?

WUFI (Wärme und Feuchte instationär – Heat and Moisture Transient) is the global standard in hygrothermal modelling, developed by the Fraunhofer Institute for Building Physics (IBP). It provides:

• Realistic simulations using hourly climate data
• Integrated rain, solar, and vapour transport modelling
• A comprehensive material database (including UK-relevant materials and custom entries)
• Risk projections for long-term moisture build-up and drying performance

At Ecosophy Studio, our team is trained and experienced in WUFI® applications, enabling accurate interpretation and practical guidance based on simulation results.

Who We Work With

Our hygrothermal assessment services are suited for a wide range of stakeholders:

• Architects and designers planning new build or retrofit details.
• Retrofit Coordinators and energy consultants operating under PAS 2035, AECB CarbonLite Retrofit, or EnerPHit frameworks.
• Manufacturers and suppliers introducing innovative products and seeking to understand their moisture response in the UK (or any other) climate
• Conservation architects retrofitting heritage constructions.
• Developers and housing associations seeking moisture-safe designs for large-scale housing schemes

Why Hygrothermal Performance Assessments Matter in the UK

The UK’s moist maritime climate creates a unique set of challenges for high-performance construction. While insulation levels rise to meet net zero goals, buildings also become more airtight and vapour-sensitive -raising the stakes for moisture safety.

Simple condensation checks are no longer sufficient. Dynamic simulation using tools like WUFI® allows for:

• Identification of high-risk build-ups before construction
• Validation of product compatibility (e.g. insulation + vapour control + membrane systems)
• Better decisions about moisture management and detailing
• Improved occupant health through mould prevention and material protection

Ultimately, it helps reduce failure risk, prolong material lifespan, and deliver buildings that are both energy-efficient, durable, and healthy.

Why Hygrothermal Performance Assessments Matter in Greece

Greece’s Mediterranean climate -characterised by high humidity, intense solar exposure, and seasonal rainfall- creates unique moisture challenges for old and new buildings. Hygrothermal performance assessments are essential for designing safe, durable, and energy-efficient constructions and retrofits. From preventing mould and condensation to protecting traditional masonry and improving thermal comfort, advanced moisture modelling helps designers make informed decisions and avoid long-term failures. As Greece accelerates energy upgrades under EU and national initiatives, understanding moisture behaviour is becoming a critical part of responsible, future-proof building practice.

Contact Ecosophy Studio today to discuss your project and learn how WUFI® modelling can support safe, robust, and sustainable building performance.