Hygrothermal Performance Assessments with WUFI®
In the evolving landscape of high-performance building design, understanding the movement of moisture and heat through building envelopes is critical to ensuring long-term durability, comfort, and compliance. At Ecosophy Studio, we offer advanced hygrothermal performance assessments using industry-leading WUFI® software, enabling our clients to evaluate the performance of walls, roofs, and complex building elements under realistic, climate-dependent conditions. Our service is designed for architects, retrofit designers, manufacturers, and developers seeking robust insights into interstitial condensation, mould growth, drying potential, and the compatibility of construction build-ups with both energy and moisture management goals. All our work is rooted in UK and international best practices, ensuring technical rigour and regulatory relevance.
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 interstitial condensation, mould growth potential, and moisture accumulation
- Evaluation of internal insulation strategies in traditional buildings and solid masonry walls
- Analysis of external insulation systems, green roofs, ventilated cavities, or proprietary membranes and tapes
- Support for ECO4, PAS 2035, or EnerPHit-compliant retrofit designs
- Custom climate inputs and material profiles specific to the UK or bespoke locations
- Comparative modelling of proposed vs. optimised build-ups to support specification decisions
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, 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 EnerPHit certification, as needed.
Why Choose 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, especially with vapour-tight, bio-based, or complex build-ups
- Retrofit Coordinators and energy consultants operating under PAS 2035 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 adding internal insulation to solid walls or 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.
Get in Touch
If your project involves retrofit, novel materials, or unusual construction details, or if you simply want to be sure your building envelope can manage moisture as well as it retains heat, we’re here to help. Our hygrothermal assessments combine rigorous analysis with clear, design-relevant advice.
Contact Ecosophy Studio today to discuss your project and learn how WUFI® modelling can support safe, robust, and sustainable building performance.