| 摘要 |
A so-called counter-flow roof has an airtight outer roof layer 11 and an air-permeable layer 12 of a porous material mounted beneath it and further a fan 16, the inlet 17 of which can be connected to an inflow air source and its outlet 18 can be connected to an air distribution space 13 which is limited by the outer roof layer and the air- permeable first layer. The air-permeable second layer 14 is arranged below and with a space between the first layer 12 and the fan's 16 outlet 18 and can alternatively be connected to the air distribution space 13 and to the interstice 22 between the first and the second layer. In the first alternative the air is directed through the fan 16 to the air distribution space 13 down through both of the air- permeable layers 12, 14. In the second alternative part of the air goes up through the first layer 12 to the air distribution space 13 and from there out into the open air through a valve-equipped outlet 23 while the rest of the air goes down through the second air-permeable layer 14. <IMAGE> |
