San Bruno-based Planet Metrics, a venture-backed publisher of software corporations use to reduce their carbon footprints, reported Tuesday that it has added two directors to its board, effective immediately. Planet Metrics identified the new members as Tyler Elm and Adam Lowry. Elm, Planet Metrics noted, is a former Wal-Mart executive who currently serves Canadian Tire Corp. as consulting vice-president of business sustainability. Lowry, Planet Metrics continued, is chief greenskeeper and founder of Method. Before that, he worked as a climate scientist at the Carnegie Institution, Planet Metrics added. Planet Metrics is backed by $2.3M in funding from angel investors and Draper Fisher Jurvetson (DFJ).