A portable, insulated shelter consists of flexible inner and outer layers, lightweight fabric panels located therebetween, and connected to each other, a suitable support frame, and a system, such as a HVAC unit and a suitable connector, for actively controlling the interior environment of the shelter. The shelter may be used to protect and provide livable conditions in harsh, remote locations. Methods of selectively installing and removing the fabric panels are also provided, along with methods of setting up and disassembling the shelter.