Climate Analysis using Weather Tool – 02

Weather Tool 02 |

Weather Tool’s Optimum Orientation Analysis | (Solar Position tab > Best Orientation)

When you use Weather Tool’s optimum orientation analysis function, the program would already define some defaults for 3 months peak overheated and underheated period, based on a weather file. Then, a fictitious surface would be rotated 360 deg. to check for initial incident solar radiation.

An optimum orientation is one that receives lowest radiation during 3 summer months and highest in 3 winter months. So, if you go with the defaults, you would assume that you’re going to use those months for the calculation. If you change the input months, you’ll notice that the optimum orientation is changed. This can be an issue for some locations like Thailand where you have only overheated months almost all year round. If you go with the defaults then the result could be misleading. For a very hot and humid climate, for example, Bangkok, you have to uncheck the underheated months and only specify the overheated months based on the weather file (kind of a judgment call on which months to use – better to check monthly or hourly temperature data).

After you get the optimum orientation, actually an orientation which differs by 10 deg. might not be that much of a difference in terms of incident solar radiation. You can check on this by clicking “Solar Position” button again and use a slider bar to check for incident solar radiation at different orientation.

Optimum Orientation Analysis screenshot

Solar Radiation screenshot (after optimum orientation is calculated)

Caveats |

Since this orientation analysis is done in Weather Tool and the only input is a weather file, this means it has not considered the impact of  neighbor building’s overshadowing or functional uses of a building at all. This is suitable for early design phase where you just want to have some ideas on how to approach a project based on the climate. Also, this result could be applicable for envelope-dominated building, while for internal load dominated building, this will affect the heat transfer at the building on the perimeter zone.

For a blank site in largely undeveloped area, then, some of the analysis derived from Weather Tool can be reasonably applied. Further analysis should be done if you’d like to test the impact of neighbor building or when you start to model your building. This will require other software tool such as Ecotect.