Why the compass lies indoors — and what it does to a solar survey
Every phone has a magnetometer. It is a good one, right up to the moment you carry it into a loft. Steel lintels, the water tank, the boiler flue, the wiring in the ceiling below — each one bends the magnetic field a little, and the compass reports the bend as if it were north.
On a heat-loss survey this hardly matters. On a solar survey it is the whole job: a roof that faces 20° further west than you think loses a chunk of its morning sun, and the installer's design will be built on the wrong number.
That is why Inkaroom takes orientation outside, at the front wall, as a separate step — and marks any orientation taken indoors during the scan as unreliable until you confirm it. Two minutes on the pavement is cheaper than a design that is 20° out.