I recently ordered the Eclipse Thermalayer Crinkle Curtain Panels from Walmart, but I found that unless your curtains start about 3 inches above the window, light will come through at the top. This is do to the fact that the blocking material starts a little lower than it should. The Thermalayer is basically 3 layers, the backmost layer being a white sheer like material. However, I found that it still let in more light than expected during the day. The crinkle fabric looked nice, but not as nice as their suede Thermaback panels (Thermaback panels have white foamy backing), but I suppose it depends what other fabric you have in your room. If you have satin, silk or other such material the crinkle fabric maybe the way to go. The Dobby material they offer is their cheapest line, but I really didn’t like how it looked. The Thermaweave line of curtains seem to not have a white back, so if that’s important you may want to look into that line. The three lines they offer – Thermalayer, Thermaback and Thermaweave are all energy efficient (insulation), block light and help reduce some outside noise. I think if you really want to save money on energy though, the curtains should go all the way to the ground, unless you have a radiator, then you wouldn’t want to cover that up. I like to put a sheer behind them, so when I do open them, I still have a little privacy and some style.