A ventilation device for a building, the device comprising: i) a heat exchange module having a first fluid inlet and a first fluid outlet, the first fluid inlet and first fluid outlet being provided in fluid communication with one another by means of a plurality of tube elements of the module; and a second fluid inlet and a second fluid outlet, the second fluid inlet and second fluid outlet being provided in fluid communication with one another by means of a conduit surrounding the plurality of tube elements; wherein the module is arranged whereby an outer surface of each of the plurality of tube elements is exposed to fluid flowing between the second fluid inlet and second fluid outlet whereby heat may be exchanged between respective fluids flowing between the respective fluid inlets and fluid outlets; and ii) first and second fans (471, 472), the first fan being arranged to cause a flow of air from the first inlet to the first outlet, the second fan being arranged to cause a flow of air from the second inlet to the second outlet; characterized in that: the tube elements are arranged to describe a substantially helical path and configured to induce a swirl in fluid flowing through the module over an outer surface of the tube elements, thereby to reduce the occurrence of areas of low fluid movement in the module. i) a heat exchange module having a first fluid inlet and a first fluid outlet, the first fluid inlet and first fluid outlet being provided in fluid communication with one another by means of a plurality of tube elements of the module; and a second fluid inlet and a second fluid outlet, the second fluid inlet and second fluid outlet being provided in fluid communication with one another by means of a conduit surrounding the plurality of tube elements; wherein the module is arranged whereby an outer surface of each of the plurality of tube elements is exposed to fluid flowing between the second fluid inlet and second fluid outlet whereby heat may be exchanged between respective fluids flowing between the respective fluid inlets and fluid outlets; and a first fluid inlet and a first fluid outlet, the first fluid inlet and first fluid outlet being provided in fluid communication with one another by means of a plurality of tube elements of the module; and a second fluid inlet and a second fluid outlet, the second fluid inlet and second fluid outlet being provided in fluid communication with one another by means of a conduit surrounding the plurality of tube elements; wherein the module is arranged whereby an outer surface of each of the plurality of tube elements is exposed to fluid flowing between the second fluid inlet and second fluid outlet whereby heat may be exchanged between respective fluids flowing between the respective fluid inlets and fluid outlets; and ii) first and second fans (471, 472), the first fan being arranged to cause a flow of air from the first inlet to the first outlet, the second fan being arranged to cause a flow of air from the second inlet to the second outlet; characterized in that: the tube elements are arranged to describe a substantially helical path and configured to induce a swirl in fluid flowing through the module over an outer surface of the tube elements, thereby to reduce the occurrence of areas of low fluid movement in the module. the first fan being arranged to cause a flow of air from the first inlet to the first outlet, the second fan being arranged to cause a flow of air from the second inlet to the second outlet; characterized in that: the tube elements are arranged to describe a substantially helical path and configured to induce a swirl in fluid flowing through the module over an outer surface of the tube elements, thereby to reduce the occurrence of areas of low fluid movement in the module.