I live in Michigan and this morning it was 15 degrees outside. I noticed that almost every window in the house had moisture at the bottom or in the case of double hung at the joint where the lock is. I know this is condensation. What is causing this? Can I repair this? This house is 130 years old, two story. All the windows have been replaced within the past 35 years. Most are double hung and double glass. They have not lost their double glass seal. I expect I'm losing energy here. With the price of Propane so high I need some answers. Thanks for your advice.