Styrofoam is a flammable material, and exposing it to direct sunlight for extended periods can pose a fire hazard. Styrofoam is not designed to withstand high temperatures, and when exposed to heat sources like direct sunlight, it can melt, release toxic fumes, or ignite.
Using Styrofoam to block gaps in your window for an air conditioner installation is not recommended. Instead, it's better to use proper sealing materials designed for this purpose, such as weatherstripping or foam tape. These materials are non-flammable and specifically designed to provide insulation and seal gaps effectively.
It's crucial to prioritize safety when it comes to home repairs and modifications. Using appropriate materials that meet safety standards will help prevent potential fire hazards and ensure the well-being of yourself and your property.