Wiktionary
build in
vb. 1 (context transitive English) to add components to a larger entity without interfering with the purpose or functionality of the larger entity 2 (context transitive English) to build something in the interior of an entity
WordNet
build in
v. make something an integral part of something else; "we can build in a special clause to make the contract better for you"
Usage examples of "build in".
If you plan to build in a rural area, they also maintain graphical representations of the average temperatures so that you may extrapolate them for your site.