The invention relates to a device for controlling the climate in a greenhouse, comprising a first heat exchanger (7) with a first series of channels (7a) and a second series of channels (7b), greenhouse supply means (1) leading from the greenhouse to the first series of channels, outside supply means (5) leading from outside to the second series of channels, greenhouse discharge means (4) leading from the device to the greenhouse and outside discharge means (6) leading from the device to the outside, wherein the greenhouse discharge means connect to the first series of channels and the outside discharge means connect to the second series of channels. The air is hereby retained in the greenhouse without supply of new air, while the temperature of the air in the greenhouse can be adjusted while maintaining a separation between greenhouse air and outside air.