Origin of the proxy data. In the ecoinvent database, proxy data has been used primarily used for estimating missing data on (1) electricity demands, (2) heat demands, (3) cooling water demands, (4) process water demands, (5) wastewater treatment, (6) nitrogen demands for blanketing, and (7) infrastructure requirements . The gap-filling approach (13) for the first six types of missing data is to use proxy data derived from the environmental reports of one specific medium-sized chemical 20 manufacturing site in Germany (located close to the city of Gendorf) , whereas the approach for missing infrastructure data includes data from Gendorf and a second German chemical production site located in Ludwigshafen .