Dear Ladybug Tools Community,
Welcome Dewbee, a Honeybee extension to run heat and moisture transfer (HAMT) simulations in Grasshopper!
Dewbee basically activates the Combined Heat and Moisture Transfer algorithm in EnergyPlus, which uses a 1D finite element approach to model coupled heat and moisture behavior in opaque building components like walls, internal mass, and even doors. The underlying model builds on the formulation of Künzel (1995), which is also used in WUFI.
Download link
Fresh from the oven in Food4Rhino: https://www.food4rhino.com/en/app/dewbee.
Features
- Seamless integration with Honeybee workflows
- Definition of moisture sources
- Access to a curated hygrothermal material database
- Easy creation of custom materials
- Targeted HAMT simulations (only where needed)
- Multi-year simulation and analysis (only for Windows at the moment, sorry folks)
Why would you even care though?
Unlike the default model used in EnergyPlus (and Honeybee), HAMT captures how heat and moisture are stored and how they move within building elements. This makes it especially important for assessing indoor climate and comfort in buildings that include hygroscopic materials such as earth, timber, and bio-based materials.
Click to read more
This is particularly true for relative humidity. Here is a comparison for Zurich climate considering a rammed earth office building:
In addition, transient behavior is captured in much greater detail. When moisture dynamics are accounted for, comfort metrics become more trustworthy. The example below shows the resulting differences in standard effective temperature (SET):
Next steps and background
Targets for the next stable release:
- Temperature and moisture profiles through components
- A more comprehensive hygrothermal material database
- Better compatibility with Mac.
- Activate Effective Moisture Penetration Depth (EMPD) Model - which is much faster, albeit less accurate, than HAMT.
Click for more background
Dewbee has been developed at the chair of Architecture and Building Systems (ETH Zurich) with support from Think Earth, an Innosuisse flagship project. It extends the scope of an earlier proof-of-concept tool called WaterSkater.
The core of my ongoing PhD is to investigate climate-responsive design with materials like earth and wood. Having used Honeybee for years, I could only see one fair direction ahead: parametric and open-source!
Citing us
Zorzetto, G., Hischier, I., & Schlueter, A. (2026). Dewbee (v0.1.2). Zenodo. https://doi.org/10.5281/zenodo.19919608
Looking forward to your feedback! Also, feel free to colaborate (Github repo).