Window shades and blinds can be very effective at blocking solar heat, light and glare; but they can also be mere decorative devices.
All depends on their type and materials, or where they are located (indoors or outdoors).
A venetian blind can block up to 50% of the solar heat if installed indoors and about 70% or 80% when installed on the exterior of the window. But a cheap exterior bamboo shade - very common in many hot climates - may only block 20% or so of the solar heat gains. They aren't as efficient as venetian blinds and new roller shades, using fabrics with reflective metalized coatings.
Blinds & Shades can help you cut your cooling costs to very low levels.
Choose effective window shades and blinds and combine them with other shading strategies and with natural ventilation.
Prices and reviews
Prices depend on the size and type of blind/shade. New roller shades are a bit more expensive than most traditional shades, but they cost a small fraction of most awnings or shutters.
Most shades and blinds have prices within the $10-$100 range (per window). See, for reviews and prices at Amazon.com: Shades and Blinds.
Below we list several types of shades and blinds - venetian blinds, bamboo blinds, wood and wooden blinds, roman shades and new "solar" shades and new thermal and cellular-honeycomb shades - and their main pros and cons from an energy-efficiency standpoint.
Cellular Honeycomb or Thermal shades
Honeycomb or cellular shades are among the best types of shades. They have air pockets in their structure to help reduce solar heat.
They are excellent to block the sun’s heat, and they operate as common roller shades or as horizontal blinds.
They are very effective for light control, and prices are very similar to other shades. They come in a range of colors.
Note: there are also shades of this type, designed to keep the heat inside during in the winter. This ‘energy-saving roller shade’ can reflect heat back into the room.
Venetian blinds are a versatile and popular choice. Exterior venetian blinds provide higher solar shading, but they need to be hardy enough and favorable locations to withstand the elements. They can block the heat up to 50-60% indoors and up to 80% or more outside.
They are relatively inexpensive ($10-$100 per window, depending on size and details) and easy to install (a DIY task).
Bamboo and wood blinds
Simple bamboo and wood blinds are inexpensive and popular in hot countries. They are reasonably effective at shading and at controlling solar heat and light when located outdoors, but their effectiveness decreases when installed indoors.
Their popularity comes from their low price and decorative value. New bamboo, wood and faux wood blinds for indoor uses are less rustic, more sophisticated and still inexpensive, but they aren't as effective as other types of blinds for solar heat control…
Roman blinds can be made from different fabrics, and come in an immense variety of colors and patterns. They do a reasonable job at controlling light and glare, but they are a poor choice for solar heat control.
Solar roller shades
Solar roller shades are made from new fabrics, with different degrees of transparency/openness. They are good for modern decorations and for light, glare and privacy control.
Room darkening roller shades (blackout shades) are the best for solar heat control. The best shades for blocking solar heat have a bright white color on their exterior-facing side, or a reflective metalized coating.
The best shades for solar control and energy efficiency are a bit more expensive, but you should prefer them; very inexpensive solar shades can be rather ineffective. Expect prices between $30 and $100 per window.