Past Perfect vs Past Simple

Solution 1:

This is a typical use of the past perfect. In a narrative like this, the use of the past perfect establishes that there is a temporal focus (even though the writer has not given any explicit information about it), and placed other events in the past relative to that focus. The reader can expect that the following sentences will relate to that temporal focus.

If he used the simple past, it would not establish a temporal focus, so the default focus of the present would apply. If the following sentences were in the past, it would not be immediately clear when they were relative to the remodelling of the houses.