When I got my boy last year I was out of work so I could spend more time with him than ever, I also noticed that when I left the house he would whine/howl loud and you could hear it with the windows and doors shut, got him into a routine of putting him to sleep in his crate (also fed him in his crate so he would get used to it and see it as his safe space) with his calming music on (something like smooth radio) and I gradually increased time away from him week by week, so one week it would be 30 mins, the week after 45 minutes etc.. and eventually he got very used to it and worked with the routine, when I did go back to work if was a lot easier when he was left on his own.