There's a reason why they are called Venetian blinds.
The weather in Venice requires some heating in winter, shading and ventilation during the summers, and humidity is always a concern in a city that is made up of islands, canals, and bridges. A local vernacular architecture developed to meet those needs as Venice built itself over the centuries.
Windows were equipped with wooden shutters, canvas shade canopies, Venetian blinds, usually installed outside the glazing to prevent trapping the sun's heat inside the house, and drapes with valences for privacy, shading, and night insulation. Each of these elements can be adjusted to provide comfort and react to the weather as it changes. It is quite a sophisticated passive solar system.
The Venetian vernacular also includes sunspaces as separate rooms or balconies. The stone and brick wall construction adds natural heat storage. The sunspace in Venice is, reportedly, an unremarked solar adaptation, a commonplace addition to any house that sees the sun, taken for granted and an everyday sight.
On pitched roofs, Venetians built the altana, a sundeck, sometimes with a canopy but always with open railings to allow the wind to blow through them. They were used for drying clothes and foodstuffs and to provide access to the sun. Often, Venetian families would eat their meals there.
People have been building solar houses since people began building houses. We just don't do it consciously most of the time. Any window that sees sunlight is a solar collector but we tend not to think of that.
Vernacular architecture works and that's why it survives. It is nothing if not practical. Our ancestors built the way they did for good reasons. We can learn a lot by understanding the old ways of building and remembering those reasons.
Based upon "Venice and the Sun" by Aldo Fanchiotti in the Proceedings of the Fourth National Passive Solar Conference (ISBN 0-89553-018-X) which happened in 1979.
Earlier entry in this series:
Old Solar: 1881
More on windows as solar energy devices:
A South-Facing Window Is Already a Solar Collector
Your Southernmost Window