ZUB Esther 6.0

ZUB Esther supports hygrothermal component simulations for typical practical construction verification and assessment cases. The software is particularly useful when simplified methods, such as the periodic balance or Glaser verification, are insufficient to reliably assess the actual moisture behavior of a design.

1. Hygrothermal Simulation of Components

ZUB Esther calculates heat and moisture transport processes in components over an extended period. In doing so, it accounts for temperature profiles, moisture content, capillary moisture transport, sorption, climatic boundary conditions, and drying processes. Hygrothermal simulation enables a significantly more realistic assessment than purely steady-state verification methods. It helps detect critical moisture developments early, optimize component layups, and evaluate long-term moisture risks. Typical questions include:

• Does the design remain permanently safe regarding moisture control?
• Can introduced or absorbed moisture dry out again?
• Are critical material moisture levels reached?

2. Dynamic Moisture Protection Verification according to DIN 4108-3 Appendix D

ZUB Esther is optimized for dynamic moisture protection verification according to DIN 4108-3 Appendix D. The software supports planners in assessing designs where a simplified verification is not permitted and a dynamic analysis is required. Its application is especially relevant for components with complex materials, multi-layer designs, renovation measures, and demanding roof or wall structures. ZUB Esther automatically sets many required boundary conditions based on the component type. This guides the verification process in a practice-oriented manner and reduces input effort.

3. Differentiation from the Periodic Balance / Glaser Verification Method

The classic periodic balance or Glaser verification is a simplified method. It primarily considers diffusion-based moisture transport under steady-state boundary conditions. Moisture storage, capillary moisture transport, solar radiation, construction moisture, driving rain, or time-varying climate conditions are either not represented or only very limitedly captured. For many standard designs, there is additionally a simplified verification via the list of verification-free designs in DIN 4108-3. For designs deviating from these or for special boundary conditions, a hygrothermal simulation is required. ZUB Esther supports exactly this dynamic analysis and helps overcome the limitations of simplified verification methods in building practice.

4. Hygrothermal Simulation with the WUFI® Calculation Engine

A key feature of ZUB Esther is the integrated WUFI® calculation engine from the Fraunhofer Institute for Building Physics IBP. In this way, ZUB Esther combines a proven scientific calculation engine with a practice-oriented user interface and a workflow aligned with moisture protection verification according to DIN 4108-3. This makes ZUB Esther particularly interesting for users who want to apply hygrothermal simulations efficiently and economically in daily planning. The software is deliberately practice-oriented and reduces many inputs that would otherwise have to be determined manually in more comprehensive simulation environments.

5. Interior Insulation

Interior insulation imposes several requirements on moisture protection. Applying insulation to the indoor surface significantly changes the temperature and moisture behavior of the exterior wall. The existing wall becomes colder, which impacts intersecting walls and ceilings. Furthermore, it must be verified whether indoor moisture from the inside or driving rain from the outside affects the design. ZUB Esther supports the hygrothermal assessment of interior insulation designs and helps verify whether:

• Harmful condensation can form,
• Moisture dries out sufficiently,
• Critical material moisture levels are reached,
• Mold risks can develop,
• The planned buildup is safe in terms of moisture control.

Simulation is particularly relevant for interior insulation with pronounced sorptive and capillary properties on single-leaf exterior walls when simplified verification is no longer sufficient.

6. Insulated, Unventilated Wooden Roof Structures

Wooden components react sensitively to elevated moisture content. For insulated, unventilated wooden roof structures, a dynamic simulation can be required, especially when metal roof coverings or waterproofing membranes are placed on sheathing or boarding without rear ventilation of the waterproofing or decking substrate. ZUB Esther supports the assessment of such roof designs by simulating the moisture development in the component over an extended period. Typical questions include:

• Does the moisture content of wood or wood-based materials rise above limit values?
• Is there sufficient drying potential?
• How does the water content develop in individual layers?

In ZUB Esther 6.1, additional functions were supplemented for this purpose, including the WTA-6-8 method for calculating the pore air humidity of wood, as well as a differentiated calculation of wood moisture levels for wood-based materials according to service classes.

7. Components in Contact with the Ground

Components in contact with the ground are among the structures where simplified moisture protection assessments do not apply. ZUB Esther 6.1 includes a calculation method for components in contact with the ground in accordance with the specifications of DIN 4108-3. ZUB Esther supports planners in tracking the moisture development of such components and evaluating the design with regard to long-term moisture safety.

8. Green and Graveled Flat Roof Structures

Green and graveled flat roof structures, as well as roof structures with slab coverings or wooden gratings, can be highly demanding regarding moisture protection. The additional layers alter the boundary conditions for heating, drying, and moisture release. ZUB Esther provides special exterior climate datasets for gravel and green roof structures, allowing these roof buildups to be evaluated for practical applications. The simulation supports, among other things, the analysis of:

• Moisture accumulation in the roof structure,
• Drying potential,
• Long-term moisture development,
• Critical material moisture levels.

9. Mold Prevention and Critical Moisture Conditions

ZUB Esther supports the assessment of critical moisture conditions within the component and at boundary layers. In version 6.1, checks for boundary layer temperatures and relative humidities for mold prevention were added. This allows planners to detect moisture risks early and optimize designs purposefully. While hygrothermal simulation does not replace thermal bridge assessments of connection details, it can provide important indications of moisture-critical component states. For detailed thermal bridge assessments of connection details according to DIN 4108-2, ZUB Argos is suitable. For hygrothermal component simulation and the assessment of the moisture behavior of layers and materials, ZUB Esther is the appropriate tool.