It's not enough for your windows to simply look good. They also need to provide adequate insulation. Leaks, no matter how minor they might seem, can quickly escalate and become worse. Apart from losing heat in the winter and having your air conditioner work harder in the summer, you will also need to worry about water infiltration. So, what can you do about it? Simple, you can test your windows regularly to make sure that they are closing properly and the glass is still sealed. There are three easy methods you can use to do this.