well, im not a genie mouse when it comes to this stuff, as i said it was just an 'idea'. I would take the air shared from an air-brick with two 160mm fans to create some pressure (under ground floor level) then I would take two runs of piping 80-90mm run it 30-40 cm under my grounding which is only 1.5 meters from the water table and conduit it through an up a thick brick chimney breast where by at the top there would be two out-take fans.. the cooling distance under the ground would be 3.5 meters and the chimney itself would also be very cold. not very scientific but the air should have enough time to get cooled (were not talking freezing air here)
could it work? perhaps i could drop a water tank under there and run the pipe through it ?