GBB IV is the utility building. It is a hybrid building: the walls of the back portion, which are partially underground, and interior walls that form small rooms are made of concrete block, while the workshop at the front of the building is mostly of ferrocement construction.
This is the only structure that does not employ polyhedral geometry. It preserves, however, the scale of the other structures by being partially underground and because it comprises three distinct volumes.
In separate (for safety reasons) small rooms, GBB IV houses the generator, PV batteries, inverter and main switchboard, the burner for the heating system, a storeroom, and a small workshop.
All rooms are arranged around our original 1974 experimental dumb-wall, which we decided to preserve for sentimental reasons. (We also joke that the 1974 wall is an ancient ruin and we can point out the name "Byron" scratched on it to prove it. Lord Byron left his mark on many an ancient ruin when he toured Greece in the early 19th century, and a friend who helped us construct the wall decided to turn it into an instant antiquity by scratching the prolific lord's name in the wet concrete.)
Each of the small rooms receives natural light from a small fixed-glass window and is vented by a grilled opening. Triangular openings at the top of the gabled workshop contribute to its comfort during summer, while two rows of glass block on the south wall provide evenly diffused light. A further two windows to the west, above the work bench, afford views to the sea.
In addition to preserving the 1974 wall, we also wanted to retain the patio we had leveled and paved, earlier in 1974, in front of the dumb-wall, and these preservation requirements, along with the boundary limitations imposed by the ravine to the north and GBB III to the south, largely dictated the footprint of the building.
From the gable of the workshop is suspended a sculptural piece — Aeolus' Balls. The system of pipes and associated cables used in its suspension relate in a manner that makes the sculpture an integral part of the building.