In addition to the table-top Moonbase model larger individual buildings were built for close-ups (and explosions, as in Force Of Life, War Games and other episodes). The buildings are approximately 1/24 scale. None of these correspond to the buildings of the table-top model. (See the continuity guide)
The individual buildings had windows that were illuminated by internal lights, unlike the full Moonbase Alpha model which used reflective tape.
Filming the model buildings. They are on the studio floor (the camera is in a sunken pit). Cut out photographs of lunar mountains are placed behind. Cut outs are easier to move and store than 3-dimensional model hills.
The shot as it appeared on screen, in The Metamorph
In these shots from War Games, it's on the left in the first shot, and on the right in the second.
Photos from Alpha:2014 convention
Behind and inside the building: light bulbs illuminate the windows
The building today, at the Alpha:2014 convention.
Inside the building.
Contents copyright Martin Willey