use variable name as HOME and variable value as %userprofile% to set the home dir in windows.By default your .ssh folder should be there.
To view or change environment variables:
1.Right-click My Computer, and then click Properties.
2. Click the Advanced tab.
3. Click Environment variables.
4. Click one the following options, for either a user or a system variable:
o Click New to add a new variable name and value.
o Click an existing variable, and then click Edit to change its name orvalue.
o Click an existing variable, and then click Delete to remove it.
Complete article to set up environment variable