Commercial buildings consume nearly 19% of delivered energy in the U.S, nearly half (42%) of which is consumed in buildings with digital control systems [23] comprised of wired sensor networks. These sensors have scant metadata, and are represented by "tags" which are obscure, buildingspecific and not machine parseable. We develop a human-inthe-loop synthesis technique which uses syntactic and datadriven steps to parse these sensor tags into a common namespace, which can enable portable building applications. We show that our technique allows an expert to fully parse a large fraction (70%) of the tags with 24, 15 and 43 examples for three large commercial buildings comprising 1586, 2522 and 1865 sensors respectively, and deploy three portable applications on two buildings with less than 30 examples.