In winter our heating costs were quite high. We live in an old building and I hated the idea of the warmth just disappearing through doors and windows. That’s why I bought these funny door noodles that only must be cut to the size of your door. Just slip them under the door leaf, you don’t have to drill holes or bolt toghether anything. And yes: We could see the impact on our hetaing bill.
Note: At the moment these door sealers are only available as plastic versions, but I hope there will soon be some made of natural materials.