Heat recovery installation, comprising: - a channel plate, comprising: - a first plate, second plate, third plate and fourth plate arranged parallel to one another; - partitions for connecting the first, second, third and fourth plate provided approximately at right angles to the latter, - wherein a first supply and discharge channel layer is formed between the first plate and the second plate, comprising alternately arranged fresh-air supply channels and used-air discharge channels separated by the partitions; characterized in that - a heat recovery channel layer is formed between the second plate and the third plate, comprising alternately arranged fresh-air heat recovery channels and used-air heat recovery channels separated by the partitions and adjoining the channels of the first supply and discharge channel layer via perforations in the second plate; - a second supply and discharge channel layer is formed between the third plate and the fourth plate, comprising alternately arranged fresh-air discharge channels and used air supply channels separated by the partitions and adjoining the channels of the heat recovery channel layer via perforations in the third plate; - a fresh-air supply header which is connected to the fresh-air supply channels via fresh-air supply apertures; - a fresh-air discharge header is connected to the fresh-air discharge channels via fresh-air discharge apertures; - a used-air supply header is connected to the used-air supply channels via used-air supply apertures; - a used-air discharge header is connected to the used-air discharge channels via used-air discharge apertures; - a first air pump is arranged for pumping fresh air from the fresh-air supply header to the fresh-air discharge header; and - a second air pump is arranged for pumping used air from the used-air supply header to the used-air discharge header, - for producing a flow of fresh air in the fresh-air heat recovery channels and an opposite flow of used air in the used-air heat recovery channels of the heat recovery channel layer. - a channel plate, comprising: - a first plate, second plate, third plate and fourth plate arranged parallel to one another; - partitions for connecting the first, second, third and fourth plate provided approximately at right angles to the latter, - wherein a first supply and discharge channel layer is formed between the first plate and the second plate, comprising alternately arranged fresh-air supply channels and used-air discharge channels separated by the partitions; characterized in that - a heat recovery channel layer is formed between the second plate and the third plate, comprising alternately arranged fresh-air heat recovery channels and used-air heat recovery channels separated by the partitions and adjoining the channels of the first supply and discharge channel layer via perforations in the second plate; - a second supply and discharge channel layer is formed between the third plate and the fourth plate, comprising alternately arranged fresh-air discharge channels and used air supply channels separated by the partitions and adjoining the channels of the heat recovery channel layer via perforations in the third plate; - a fresh-air supply header which is connected to the fresh-air supply channels via fresh-air supply apertures; - a fresh-air discharge header is connected to the fresh-air discharge channels via fresh-air discharge apertures; - a used-air supply header is connected to the used-air supply channels via used-air supply apertures; - a used-air discharge header is connected to the used-air discharge channels via used-air discharge apertures; - a first air pump is arranged for pumping fresh air from the fresh-air supply header to the fresh-air discharge header; and - a second air pump is arranged for pumping used air from the used-air supply header to the used-air discharge header, - for producing a flow of fresh air in the fresh-air heat recovery channels and an opposite flow of used air in the used-air heat recovery channels of the heat recovery channel layer.