Hi,
When I open an idf file with the IDF editor and create an "Site:GroundReflectance" object, I can see that the default value is 0 for each month.
Since I did not specify any value for this object, I though that EnergyPlus used a ground reflectance of 0 for each month in the simulations I did.
I created a new "Site:GroundReflectance" object with values of 0.1 for each month of the year, to see how it impacts on my heating and cooling needs. The results I get are strange : an increase of heating needs, and a decrease of cooling needs. I was expecting the opposite with a higher value of monthly ground reflectance...
So I did the same test with a ground reflectance of 0 for each month, and I obtained even more heating needs and even less cooling needs. That means the default ground reflectance is not 0, and it seems to be higher than 0.1.
If someone now what is the default ground reflectance value taking into account by EnergyPlus, please tell me and give me the source of this information because I did not find it in the documentation...