Properly insulating a house is essential to achieve adequate comfort and efficiency. However sometimes the insulation prevents the desired outside temperature from entering the house (for example if you want the warm afternoon sun to heat your cold house).
So I propose a building block with a thermal
conductivity that can be varied.
This block would have three layers: two conductive layers sandwiching an insulating layer. The core of the block would have a hole extending through it (the axis of the hole co-planar with the layers). A cylindrical component would loosely fit in the hole. This cylindrical component would also be made of longitudinally extending layers: two insulating layers sandwiching a conductive layer.
The idea is the cylindrical component can be rotated from an insulating configuration (with layers of the block and the cylinder co-planar) to a conducting configuration (the layers of the cylinder are perpendicular to the block such that the conducting layer of the cylinder forms a conductive path between the conductive layers of the block).
The blocks would be stacked together like bricks (sans the mortar) with the cylinders linking together. The blocks at the ends/corners of the walls would contain a small motor to rotate the cylinders.
The blocks would run on a simple algorithm such as:
Heat mode: IF outside>21 THEN conductive ELSE insulating.
The blocks could also be used in the floor utilising the fact the the ground is about 14 year round.
I'm posting this from my phone in a remote location (Thredbo) so unfortunately I can't provide illustrations.