Hi and welcome!
Well Gerdi... Maybe put a fan on you while you exercise? Low Impact exercise? A nice stroll after dinner counts. You don't have to power walk...
Unfortunately if you are looking for weight loss the most effective way to do that is raising your heart rate for 30 minutes plus several days a week...hence sweating... Low impact and weight loss can be done but it does take a longer time to see results. If that is okay with you I say go for it!