A HAND HELD DIGITAL THERMOMETER is very useful to take readings from areas of the room without leaving your seat. Constant readings from different room areas allows you to investigate places which suddenly appear cold.
We bought one such device from eBay for just £15.00 and it works well. It uses a laser pointer for up to 30 metres away to record temperature readings at a given point. However, you need to remember that the red laser pointer will read the area your pointing at, so if you point it towards the floor then the temperature of the floor you will get, and a floor is always going to show a lower reading than the rest of the room. We advise that you only use the laser pointer on a difficult to get too area. Most, if not all, digital hand held devices have an option to turn the laser pointer on and off.
The need to have one with you at all times is obvious. There is plenty of evidence that states when paranormal activity is taking place, a spirit being present for example, the area of interest will show a marked difference in temperature.