A 10" metal culvert was incorporated into each large room as a means to bring fresh air into the earthship. These "snorkels" were covered by the final berm so that heat can transfer to/from the berm to temper the incoming air.
Though these snorkels have been there since the very first stage of the build, they have not been used to date because they needed covers to keep rain, insects and animals out.
Where the intakes enter the building we installed 1/4" welded wire mesh.