Heat Insulation

Got up at six-thirty and walked to the living room in pajamas without flinging a gown on or socks as usual. Surprised to find the wireless thermometer, which I had set up outside on the balcony wall(pointed by a blue arrow in the photo), showed 10.8 ℃. Incredible!
The thermometer in the living room indicated 23.6℃. We haven't used the heating system even once yet. Still this new house provides the constant environment for us.
Heat insulation. That's the word for saving energy in our everyday lives.