[Interior, detail of air ducts.]

[Heating control valve on 17th floor of unidentified building.]

[Interior, basement with air ducts.]

[Interior, basement with air ducts.]

[Interior, basement with air ducts.]

[Interior, basement with air ducts.]

[Interior, basement with air ducts.]

[Interior, basement with air ducts.]

[Interior, boiler room.]

[Interior, detail of meters.]

[Interior of unidentified building, possibly a factory.]

[Interior, boiler room.]

[Interior, boiler room.]

[Interior, possibly a basement, with unidentified equipment.]

[Interior, radiator manufacturing shop.]

[Interior with machinery.]

[Interior, boiler room.]

[Machine room.]

[Exhaust system on roof.]

[Brick wall cut-away with embedded drainage pipe.]