ABSTRACT
In passive systems the sun acts alternately as a thermal friend and enemy. Within such a dichotomy, Harold Hay was concerned, among other things, with the actions of shade, and more precisely, changeable shading. Just like the seasonal shading provided by deciduous trees and vines, unfixed shading devices outperform static ones. Fixed devices provide maximum shade at June 21, maximum exposure at December 21 and half-shade at both equinoxes. Contrarily, deciduous vines provide peak shade in July, still shade at the hot fall equinox and then allow maximum solar exposure throughout the cold winter and cool spring equinox.
The temporal frames of passive design energy became further developed in Hay’s movable roof panels that can perform daily. Hay’s Skytherm is truly an example of “thermal sailing.” This chapter demonstrates how temporal aspects of his inventions have influenced some of my own passive design proposals.
