What pbuilder can do
What pbuilder is/can do
building Debian package in clean-room environment
allows proliferation of Debian source building lab environment 
simplify chroot management, allows multi-distribution targets
Easier creation of backport repository
Specify --othermirror for your local apt repos
pbuilder create; pbuilder update; pbuilder build *.dsc; pdebuild
sanity checking on package build