Abstract: A ventilation system including a heat recovery assembly having a first heat exchanger for heat recovery with a first flow path and a second flow path to exchange heat energy from air transported in one of paths to the other. A peripheral inlet to the first flow path is arranged to surround a central outlet of the second flow path and a peripheral inlet to the second flow path is arranged to surround a central outlet of the first flow path. The assembly further includes a peripheral outlet and a central inlet, the peripheral outlet arranged to surround the central inlet, and the heat recovery assembly is arranged such that air entering the peripheral inlet of the first flow path exits by the peripheral outlet; and air entering the central inlet will exit by the central outlet of the second flow path.