The chair has a collapsible frame (1) with a flexible tension proof cover (2). At least one panel of the cover incorporates a flat heating element (7) powered from a solar panel (9) located close to the chair. The heater can be in the form of a circulation system on the rear of the cover supplied with liquid through a control valve and fitted with an expansion vessel with heat supplied by an adjacent solar collector. Other forms of heater are an absorption layer heated by reflected sun's rays or a L.V. heat conductor supplied from a photoelectric solar powered battery.
