How to get user home directory on Windows?

I'm developing a cross-platform library that is meant to load configuration files from a user's home directory. The idea is to automatically provide configuration parameters without editing code.

This library can be used in desktop apps or in daemons/services. In (I assume) most Unix environments I can use getpwuid() to get the home directory of the user. In Windows SO told me I could use SHGetKnownFolderPath but its documentation says its for desktop apps only. Is there a way to get this path, on Windows, for the user running a service?