We have a lovely airy extension to our house which has created a large kitchen/dinning room and an extended sittingroom. As part of the renovation we have underfloor heating in a concrete floor and a Karndean flooring, which extends through the whole ground floor. And a lot of glass. We love the airiness in the spring, summer and autumn, but in the winter the rooms feel echo-y and in need of something to reduce this. We have curtains and cloth blinds and a couple of rugs, but don't want to impair the underfloor heating capabilities. What would others suggest to reduce the echo?