Abstract: A heat absorbing window which can receive solar energy and transmit the illumination part of the solar energy, while utilizing the heat part of such energy to provide a source of heat for useful purposes. The window includes a frame with three window panes. The outermost pane faces the exterior and is of non-heat absorbing material. The middle pane is of heat absorbing material, and the innermost pane can be either clear or of absorbing material. The space between the first and middle window panes defines an insulation space therebetween. The space between the middle and the inner window panes defines a fluid chamber wherein a fluid is passed. While in the chamber, the fluid is heated from the heat absorbed by the abutting heat absorbing window panes. The heated fluid is sent to a heat exchanger to extract the heat and provide useful heating purposes.