Not really. Heat travels 3 ways - convection (as in hot air rising in a medium), conduction (put a metal rod in a fire and touch other end to feel the heat), and radiation (as in solar energy traveling through vacuum of space to earth as radiant energy). The latter works through vacuum.

There was protection - “the portal is ‘ray shielded’ so you’ll have to use proton torpedoes”, according to Dodonna in ANH