An electrical enclosure system for transferring heat from a closed environment, includes an electrical device having a heat-generating part, and a polymer-based ventless housing for protecting the electrical device from environmental contaminants. The ventless housing fully encloses the electrical device and includes a base layer forming an impact-resistant portion of the ventless housing. The base layer includes one or more open areas in close proximity to the heat-generating part. The ventless housing further includes an integrated thermally conductive layer that forms a heat-flow path for conducting heat away from the heat-generating part towards an exterior environment. The integrated thermally conductive layer is molded around the base layer such that portions of the integrated thermally conductive layer cover the open areas of the base layer.