BUILDING SCIENCE TOOLS
Drop in a year of measured hourly temperature and humidity and watch the mold index respond hour by hour, using the VTT model that underpins most modern mold-risk assessment.
Mold risk is not a single number you can read off a wall section. It depends on how long a surface stays wet, how warm it is while it does, and what the surface is made of. This tool steps the VTT model through your data one hour at a time, so growth accumulates through wet spells and recedes through dry ones — the same way it does on a real building.
Load a CSV of hourly conditions, or drive the model live with the sliders to see how temperature and humidity trade off against each other.
Three columns: timestamp, temperature, relative humidity. Fahrenheit, semicolons and logger preambles are handled — sub-hourly readings are averaged up, coarser ones interpolated down.
file.csv
5.0 % above critical — growth possible
Surface finish
Sawn / resawn — SQ = 0
Surface view
Mold index
No growth
Spores present but dormant. Nothing has started.
Visual scale
Start the simulation or drop in a CSV to plot the series.
VTT model (Hukka & Viitanen 1999; Ojanen et al. 2010 sensitivity classes), stepped hourly. Results describe the surface conditions you supply, not a whole assembly — pair with a hygrothermal analysis before drawing conclusions about a real wall. For a steady-state look at where those conditions come from, start with the Glaser method calculator.
