Infrared Thermometer

We take temperature with our hands, and of course it is not very scientific, we could probably detect if something is a few degrees difference, but nothing accurate.  

Between our hands and a calibrated thermal imaging camera, there is something in between, surface temperature probe.  You can even plot your own thermal image, by taking temperate in a fixed grid and colouring in a sketch of the room.

I think an infrared thermometer is the perfect economical tools to identify the worst offending cold spots, and we tackle one heat sink at a time...