A sensor device for determining at least one heat transfer parameter of a gas comprises a sensor unit (10) comprising at least one heater element and at least one temperature sensor. A first (inner) housing (20) receives the sensor unit. The first housing comprises a first membrane (22) allowing a diffusive gas exchange between the exterior and the interior of the first housing. The first housing is received in a second (outer) housing (30). The second housing comprises a second membrane (32) allowing a diffusive gas exchange between the exterior of the second housing and the exterior of the first housing. Thereby temperature gradients inside the first housing are reduced. The second housing can be made of metal and can be disposed on a support plate (40), taking the form of a cap. An auxiliary sensor (50) can be arranged in the space between the first and second housings.