DIY Heat Blocking Curtains

Quite simply, just find whatever reflective material you can and hang it as a curtain.

"Summer is nearing/here, and it's getting hotter in my house. To save electricity with our super expensive A/C, I constructed reflective curtains to block sunlight from warming our house. Think auto windshield. This is super simple and kind of obvious, but it works well."

Heat blocking curtains - Instructables