Shading from the sunFor afternoon m

Shading from the sun
For afternoon matches, which are the majority, the main stand should face east with a minimum of spectators having to look into the sun from a west- facing stand.
In all cases the efficacy of a roof in shading its occupants from the sun, and the extent of shadow it casts upon the pitch at different times of the day and year, must be studied by careful computer modelling. Such modelling should proceed in par- allel with wind tunnel testing, especially if the play- ing surface is to be natural grass, because ‘it is now generally accepted that a combination of shad- ing from sunlight and reduced airflow at pitch level has an adverse effect on the durability and quality of grass’, to quote Britain’s Football Stadia Advisory Design Council.
Shelter from wind and rain
As far as plan shape is concerned, designers should note Rudolf Bergermann’s advice that continuous roofs arranged in a circle or ellipse, as opposed to separate roofs with gaps between, normally have a calming effect on the air inside the stadium. This cre- ates more comfortable conditions for spectators and performers – experience at the Don Valley Stadium
Front edge of roof
30o
in the UK actually suggests that such improved conditions can measurably enhance the perfor- mance of athletes. One disadvantage is that too little airflow in wet climates may give inadequate drying of a grass pitch after rain, which may argue in favour of open corners between the stands. A balance must be struck between such differing and possibly contradictory factors.
As far as cross-sectional shape is concerned, very approximate rules of thumb are given in Figure 5.7.
These simple parameters are only a starting point for design, and detailed studies should be made using scale models and wind tunnels. Factors to be included in the investigations are:
• Prevailing wind directions and velocities.
• Prevailing air temperatures, and whether winds at
match times are likely to contain rain or snow.
• Local patterns of air turbulence caused by sur- rounding buildings and, of course, by the pro-
posed stadium design itself.
• Conflict between the needs of spectators (wanting
protection from wind and sun) and the desirability of a natural grass pitch.