The relative sizes of the parts of a design to each other are the proportions of these parts. These relationships are therefore a fundamental aspect of the design process and proportion is the skeleton on which the building fabric is hung.

From ancient historical buildings proportions can be deduced, for example Egyptian tombs and temples can be linked to the Fibonacci series. The analysis by Barry Kemp and Pamela Rose showed that various aspects of Egyptian culture and religious buildings involved variations on this series.

The classic sequence is 0,1,1,2,3,5,8,13,21 … where each number in the series is the sum of the two previous ones. When any number above one is divide by the next (e.g. 5 divided by 8) the result is roughly 0.62. This result holds for all numbers in the sequence to infinity. This relationship of dividing one part to the whole in this ratio has become associated with the Golden Section. It has long been held that these proportions are pleasing to the human eye.

Both the Fibonacci series and the Golden Section have been identified throughout the human and natural world, from the growth patterns of Nautilus shells and the pattern of flower petals to architectural dimensions in Classical Greece and Rome.

When the Pythagorean mathematicians were developing the power of numbers they were also encoding musical sequences which have evolved into our modern day system. The Dorians, at a similar time, were building their temples and Palladio in his "Four Books of Architecture" measures and traces the numerical relationship of

These relationships can be found in Japanese architecture, Mediaeval and Classical European buildings. From the Renaissance, and studies by such figures as Palladio, proportions were identified which led to the 18th century pattern books. While outstanding artists have always manipulated proportion to the greatness of their works, the framework of the pattern books allowed even the country builder to produce works with harmony in their overall proportions and in the particular aspect of the windows and doors.

The Modern Movement consigned all talk of proportion to historical irrelevancy. You can now spend years studying Architecture without a reference to proportion. The manufacturers of doors and windows similarly by the evidence of their products have rarely if at all considered proportion.

Consider the example pictured above, of an extension, where the Conservation Officer has requested all the right aspects of design, the extension is thatched with rendered walls, but no one has addressed the proportion of the 'standard' door frame with its jarring proportion of 3 to 7.

On a Listed Building extension that we designed in Melbourn we gave the windows a 3: 5 and 3: 4 proportion and as Palladio advocated these ratios are the glass or "void" with a 1/6 architrave. The entrance door was sized to a 3: 6 ratio of two squares.

We have used the Fibonacci sequence numbers on a barn frame window and while not classical, gives an overall harmony with the main height to width proportion of 3 : 5. If the standard window manufactures products and especially their UPVC offerings were designed with some small consideration given to proportion, what an improvement could be achieved to buildings up and down the country.