Waldram Diagram

A Waldram diagram is an aid to the calculation of sky factors. The axes are arranged so that the contribution to the illumination at a point from an overcast sky is proportional to the corresponding area on the diagram. So if one determines the area of unobstructed sky on the diagram, this area, expressed as a fraction of the total diagram area gives the sky factor at the point.

The two Waldram Diagrams on the right show an example of the amount of sky visible from a window. The top diagram shows an existing neighbouring building in green, the building being developed is shown in red on the bottom diagram.

It is apparent from the diagrams that both existing and proposed buildings produce a similar vertical angular obstruction of about 65 degrees. The reduction in visible sky is due to the proposals increased width. Moreover this increase in massing is predominantly to the right hand side of the diagram.

view larger Waldram Diagram

view larger Waldram Diagram

Animated Waldram Diagrams

Waldram diagrams can also be used as a convenient means of visualisation. We can produce animations using them as a 'view' of a model. One can observe the movement of the sun on an animated Waldram Diagram as shown in the animation on the left.

There are various types of Waldram diagrams. Horizontal or Vertical according to the orientation of the plane on which the light is incident; and Uniform or CIE depending upon the intensity distribution of the overcast sky.

The animation above requires a Quicktime plug-in. If it does not automaticaly play then follow the Quicktime link to download the Player.

back introduction