Hygrothermal building analysis

© Fraunhofer IBP
© Passive House Institute US

Headquater of the Rocky Mountain Institute - modell in WUFI Passive

© Passive House Institute US

Headquater of the Rocky Mountain Institute - certified with WUFI® Passive.

The interaction between building envelope and the rooms it encloses is the main factor determining the hygrothermal behavior of a building. A comprehensive view of all boundary conditions that affect this interaction enables a detailed analysis of energy demands, indoor climate and hygrothermal conditions inside the building envelope. This view is derived from both experimental sampling and the evaluation of boundary conditions, including inner sources of heat and moisture, air exchange, measured and simulated weather data sets, as well as from user preferences regarding temperature and humidity set-points, or window opening patterns in different climate zones. The research findings flow into the development and application of hygrothermal building simulation tools.

Hygrothermal building monitoring paves the way to new solutions that are developed to avoid critical conditions, improve hygrothermal comfort and to reduce energy consumption. Models are developed based on measurements derived from monitoring under real conditions and in the lab, as well as on theoretical relationships. Once these models have been validated, they are implemented in the WUFI® Plus/Passive software. By combining hygrothermal building component simulation and energy building simulation, integral solutions are developed that take into account conditions in the room and in the component, as well as how these interact – while not neglecting the influence different approaches have on energy consumption. This not only leads to strategies that can be adapted to best serve homes and offices, but also to recommendations on passive measures that can, for example, enhance climate stability in historic buildings. The existing simulation environment makes it possible to quantify the influence of different climate zones, usages, component assemblies, geometries, alignments and building operation strategies on indoor climate, energy consumption and the extent to which the building envelope remains damage-free.

Hygrothermal building monitoring

Hygrothermal issues in buildings are often influenced by more than one factor. Mould growth for example can occur due to critical detail solutions, a high moisture production in the room, insufficient ventilation or a combination of several factors. The scientists of the work group »Hygrothermal Building Analysis« records temperature and humidity conditions as well as the user behaviour and assess them. This allows the development of solutions to avoid critical conditions, to improve the hygrothermal comfort and to reduce the energy use of the building.

Model development and experimental validation

Besides energy related analysis hygrothermal building simulation allows the assessment of the indoor environment and to assure a damage free construction. To perform realistic simulations it is on the one hand necessary to represent physical relationships in best possible detail. On the other hand models need to be developed, which take into account e.g. windows, thermal bridges, user behaviour or air exchange in a simplified but sufficiently accurate way. Models are developed based on theoretical relations and measurements in laboratory under realistic conditions. In a next step these models are implemented in the WUFI®Plus software.

Hygrothermal whole building simulation studies

Connecting hygrothermal building component analysis with whole building energy simulation allows the development of integral solutions, considering the conditions in rooms and components and their interaction without neglecting the influence of different approaches on energy use. In this way not only adjusted strategies for residential and office spaces can be developed, but for example also passive measures to ensure a stable climate in historic buildings. With the existing simulation environment the influence of different climate zones, building uses, component assemblies with varying materials, geometries and orientations as well as different building operation strategies on indoor environment, energy demand and durability can be evaluated in detail. Based on those investigations refinement strategies may be developed that concentrate on the most efficient and cost effective improvements.

Knowledge transfer into practice

Research results and their interpretation are made available for the building science community as well as for building practitioners by presentations and publications in national and international conferences and journals. Furthermore it is integrated in the hygrothermal whole building simulation software WUFI®Plus. The intention is to provide the architect or engineer with a tool that allows not only comprehensive simulations and analysis but also good usability. The documentation of the software features, the compilation of training material and the conduction of seminars prepares the gathered know-how for practical use.

Building concepts for new markets

Energy efficient building concepts for growth markets in e.g. Asia are adapted to compact urban building techniques and different climatic boundary conditions. Measures to maximise comfort by simultaneously reducing the fossil energy use are evaluated through hygrothermal building analysis. Furthermore building products and systems are developed together with industrial partners, which are cost-effective and provide besides technical quality also an added value by better service for the users and improved standard of living.



Improved simulation tools

WUFI® Plus and WUFI® Passive are user-friendly software programs that use sophisticated computer modeling to depict a building and its energy and hygrothermal behavior.



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Florian Antretter

Contact Press / Media

M.Eng. Florian Antretter

Fraunhofer Institute for Building Physics IBP
Fraunhoferstr. 10
83626 Valley, Germany

Phone +49 8024 643-242

Fax +49 8024 643-366