Install an electric heater in a wall with this Letsfixit guide. If you have ever needed heat in an area that has never had heat you have some options. Here is an article about a specific electric wall heater, there are many so you will have to find the right one for your application. This guide will tell you how to install one. Keep in mind the wire needs to be installed by a qualified technician
First you will need to determine the size heater for your room size Here is a simple chart or you can contact the company you choose to buy the product from. An 8x12 foot room is 96 sq ft so you will need at least a 960watt heater (8x12 = 96 sq ft times that by 10 and you get 960 watts)
Install the cavity into the wall and attach it to the 2x4 s that you installed.