The transmission is mostly what you care about for heating.
In a cooling environment, you can reflect 90% of sunlight, and the room will still be bright. Sunlight is thousands of times brighter than room lighting.
It gets trickier if you are in a net heating environment, but you have hot summers. Now you have to strike a balance between too much incoming light in summer with high heat bills in winter.
One good compromise is to let the light in, with a normal window, but have a canopy that can extend far enough to block the sun most of the time. This you adjust for time of year. You likely will still want solar heating on March 22 (spring equinox) but not want it on September 22 (fall equinox -- same solar path)
You may also be able to find films that have variable reflectivity depending on the angle of incidence.