xkcd #3099: Neighbor-Source Heat Pump
Title text:
The installation of the pipes on the inside of the insulation can be challenging, especially when the neighbor could come home at any minute.
Transcript:
[Two houses are shown next to each other. They have almost identical facades with a base, two windows on either side of a door and a chimney to the right on the roof. But next to the left house there is a small box with two light-blue pipes going from the house to the box. From the bottom of the box two similar light-blue pipes goes a bit down under ground, the left further than the right, and then they bend to the right and goes under the neighboring house to the right. The upper pipe closest to the ground is shown to enter the wall of the right house, going almost up to the roof, and then bending sharply around going down below ground. Then it goes under ground to the other side of the house and do the same in the right wall, going up and down. Where it goes under ground, it connects to the the other pipe that has gone all the way straight under the house.]
[Caption below the panel:]
A covertly-installed Neighbor-Source Heat Pump takes advantage of the fact that your neighbor keeps their house cool in the summer and warm in the winter.
Source: https://xkcd.com/3099/
