Hello XXXXXX,
Welcome to Just Answer.
Sorry to hear about your problem.
It sounds like with the installation of the new windows, that your house is tighter now than it used to be. If the windows are a decent quality, double pane, and do not have any major air gaps allowing cold air in, then your new windows are most likely fine.
Condensation and frost on the windows is a sign that the humidity is too high in your house. The humidity or water vapor in the air is caused by humans respiration and perspiration, showering, bathing, cooking, gas appliances, washer and dryer, plumbing leaks, exposed dirt crawlspaces, indoor pools/ spas, fishtanks, greenhouses with plants, etc. All of these add up and dump water vapor into the air, but there are ways to control it and it is good to start with the larger sources.
Using ventilation all the time will help; always use exhaust fans when showering and cooking and verify that they are exhausted directly to the outdoors. A dehumidifier can help pull moisture out of the air, as well. If you currently use a humidification system, I would stop using it. As your house gets tighter, you need more ventilation to keep the humidity levels down. Exhaust fans help, as I mentioned above, and this requires no cost to you, if they are working properly. If you want to take some extra steps you can purchase a heat exchanger and have it installed, usually with modifications to your heating system, that allows stale moist air to be exhausted out, while bringing in fresh dry air. The heat exchanger heats the air coming in by transferring it from the heated exhausted air. The humidity should be between 30 and 60 percent in a residence and it sounds like you are at a pretty decent level. I would just exhaust everytime the shower runs and at cooking times to see if that helps. Let me know if you have a dirt crawlspace because that can dump large amounts of water vapor into the air.
If you need further help or clarification on this answer, please do not hesitate to reply to this post.
Thanks for asking your question at Just Answer.
Best of Luck, Brian
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Architect
Licensed Architect- 12 years, L.E.E.D. AP, Former Remodeling Contractor- 10 years