AJ 18.06.20: Climate changeAs the AJ submits its RetroFirst campaign to government, our climate change issue features building studies of an ultra low embodied carbon building by Practice Architecture and La Borda social housing complex by Lacol arquitectura cooperativa; results of a new in depth survey by the AJ on what Architects Declare has achieved; the shortlists for AJ100 2020 are revealed and Paul Finch uses his column to argue that solar farms need much better design