Heated second window in a double glazing system

A window comprising:

• a window frame in a wall of a room;
• a sash fitted in said window frame;
• an outer glazing mounted in said sash;
• a second glazing mounted to one of said frame, said sash and said outer glazing, and at position interior to said outer glazing, so as to form an air circulation space between said second and outer glazings;
• means for heating said second glazing;
• and
• apertures in at least said sash and positioned for forming an air circulation path from outside said outer glazing, through said air circulation space and into the room,
• wherein said apertures comprise at least one lower aperture in a bottom crosspiece of said sash and at least one upper aperture in a top crosspiece of said sash, and
• wherein said at least one lower aperture comprises a single aperture extending substantially the width of the outer glazing and connecting said air circulation space with the outside,
• whereby fresh air circulating into the room is heated by said heating means.