I understand your concerns—I used to worry about this myself when my neighbors were renovating. Impact-resistant films really come in handy in situations like this. They’re applied directly to the glass, and when an impact occurs, they simply hold the cracked shards together on the adhesive layer. This means the window won’t shatter into dangerous shards all over the floor, which is especially important when there are small children at home. As for light, don’t worry at all. High-quality protective films are completely transparent and don’t change the appearance of the window at all. You can check out the options here: http://www.tintfit.com/shop/safety-security. It explains the different thicknesses and protection levels for various needs in detail. I went with the medium thickness, and there’s definitely no less light in the room. Do you have plastic or wooden window frames?