Dragonfly returns relative humidity > 100%

ladybug-tools
1

Hi everyone,

I’m using Dragonfly to generate an EPW weather file taking into account the UHI effect of a dense city.

I got strange outputs for Relative Humidity: among the 8760 values, 2 hours are above 100% relative humidity (102% and 104%). How can I treat this error? My initial EPW file (the rural one) does not have any hour where RH>100%.

Any ideas?

I can send the files if needed. Thanks in advance!

Best.
Julien

2

Hi @JulienFBC ,

EPW files are actually permitted to have relative humidity values as high as 110% and you can see this here in the EnergyPlus documentation:

Admittedly, I don’t know if this is because conditions higher than 100% represent some super-saturated state like a fog where humidity is technically precipitating out of the air but the droplets are small enough that they’re still suspended, or if it’s the result of something else like the saturation line shifting in the case of lower/higher air pressures.

But, long story short is that RH values greater than 100% are not an error and you’ll still be able to run energy simulations with EPWs that have such values. My recommendation is just to leave your EPW as it is.

3

Hi Chris,

thanks for the quick reply.

Interesting to know, I wouldn’t have guessed! I’ll take a look into it, if I find what these >100-values correspond to, I’ll let you know.

Best,
Julien