If you can't find a green venue then take your ecosystem with you. Create the ecosystem to fill your available space with diversity of tools
An ecosheet (turn lights off, use of water, think and what we like) use your design skills! Reuse the sheets, let them evolve.
relabel cups so we don't wash them all the time
measure electricity / watt bug and let people know (jazzy sign on wall)
carry compost back and feed the worms
open recycling up carry your labels
measure waste don't hide it don't flaunt it but do design it
Guerilla signs to save water, turn off lights and hint (look pro, left behind print extra for participants)
create a subtle market for the outcome we need
policy and labelling, pictures and marketing
acknowledge the greenwash and float above it
make some portable devices to generate rather than extension leads
make this package part of your process