Johnson himself would probably insist that the design is not very original, deriving from Mies van der Rohe's earliest projects for the Farnsworth house and a dozen or more historical precedents that he has listed in print.  And he has also said that it is 'not a controlled environment' (apparently because it has no air-conditioning). Whatever his personal opinions, the result is discovered by inspection and habitation to be an unique example of environmental management in an extended sense. For a start, what Frank Lloyd Wright (who was expectedly rude about the design) would call 'modern opportunities' in servicing have been exploited not merely to spread or 'articulate' the plan, but to split into two distinct units; one the almost entirely solid-walled guest wing, the other the totally-glazed living pavilion—a realisation of Scheerbart's detached veranda, if not by intention—more obviously related to the Farnsworth project. Simpler than the Farnsworth design, it presents itself to the observer as an undifferentiated rectangular enclosure of glass, detailed only to the extent of four recessed steel corners, and a full-height door in the centre of each of its four sides.

The glazing is not doubled, so—from the point of view of heat, light, vision and acoustics this is the lightweight wall in extremis. A brick drum, suggesting a mechanical core, rises from the floor and passes through the flat roof-slab; it contains a working bathroom, and, on the side toward the main living area, a fire-place which also works—but at the mainly ceremonial level of most of Wright's spectacular hearths. It makes a psychologically satisfying display of combustion, and radiates heat over a limited area. Yet the entire floor plan, even to the most remote glazed corners, is thermally habitable even when snow lies on the ground and against the glass. Heating is, in fact, provided by electrical elements in both the flcor slab and the roof slab, and since this requires no visible outlets or registers, the house, under normal conditions when the fire is unlit, provides an ultimate example of invisible heating services.

But in the height of summer it remains equally habitable, and this is the more baffling at first sight because of the lack of any visible sun-controls beyond some internal curtaining. The cooling and sun shading provisions are, however, 'concealed' in full view in the surrounding landscape. The glass house stands on a (partly artificial) bluff projecting from the fall of quite a steep slope that descends from the road at the top of the site to the pool at the bottom of it. The bluff looks west, through a bank of well grown trees rooted at a lower level, and these trees give adequate shade, when in leaf, to the thermally critical south and west walls. Furthermore, the slope and its trees seem to encourage a mildly breezy local micro-climate even when there is no general wind, so that the glass opening of two or more of the doors will provide any necessary cross-draught. The same trees, floodlit, also provide a spectacular nocturnal environment even in winter, and the isolation of the house from the public road guarantees visual privacy.

In practice, only two sets of conditions seem to reveal any serious shortcomings in its environmental performance. One is when fine summer weather brings determined architecture lovers down the drive without a by-your-leave, to interrupt Mr Johnson's privacy. The other is when a very prolonged Indian summer brings low hot sunlight into the house through already leafless trees; at such times the internal blinds are not always adequate to the heat-load of the early afternoon. These few days, however, hardly seem too high a price for a house in the country, to recall Wright's proposition, that is the delightful thing that imagination would have it. Forty years after the Robie house, Philip Johnson produced (only once, it seems) a masterly remixture of mechanical and architectural environmental controls that was as subtle and successful as Wright's. Admittedly, he had innumerable advantages both in budget and site, that are denied to most other architects, but one must still wish that those other architects would more often seize hold of the advantages they do possess with the same imagination and practical craft, and extract more environmental profit from their briefs, budgets and sites