The Weather Tool: WeaTool
Note these instructions refer to Version 1.10
The Weather tool is an integral component of the Ecotect design software. It provides 3 main functions:
Proper use of the final two functions requires a high skill in interpreting data presented in many formats. To make best use of this tool you will need to develop good skills in this area.
Preparation of data
WeaTool will convert hourly ascii climate data files in a separated (tab, comma, space) format. It will accept data in a range of units and formats. The following represents the current set of parameters accepted by the software:
Note that not all of these parameters are strictly required as their is an interdependence of some provided to give flexibility. For example, of the Psychrometric data, only 2 are necessary as the remainder may be calculated from these two. If your data is incomplete, then this may be OK (for example you do not need to worry about Rainfall data unless you are particularly interested in this). However the absence of some parameters may make the design tools nonsensical.
You should have your climate data prepared before using Weatool and be aware of the units and order of parameters. Make a note of Time Zone, Longitude, Latitude and Altitude. It is recommended that you retain the data file from which the Ecotect weather file will be produced as this can be used to help validate the conversion.
To load your data, select Open, telling WeaTool to look for Files of Type: 'Separated Value Files'. WeaTool opens your file and produces a view window of the file. Simply select each parameter, in order from the left hand window, add and, then check the units. You will need to specify a name for the location along with Latitude, Longitude, Time Zone and Altitude (check the sign convention). A general rule when checking any data formats/signs when the help files are not helpful: is to examine any datafiles which are already incorporated in the software. When the specification is complete, simply Import Data and save the file. It is sensible when naming the weather file that you find some way of identifying which weather files you have created and which 'came with the software'.
Make some simple checks of the data by using the various data presentation facilities of the software.
Presentation of climate data
You will of course need to have Opened an appropriate WEAther data file. The tabs on the left hand-side permit examination of monthly, weekly and hourly data. You can also specify the period over which you wish to concentrate. Many of the charts are quite complex and it is important to spend some concentrated time in achieving a proper understanding of the charts: for example what each plotted point represents: is it an average value say? and for what kind of period does it represent (hour, day, month ...).
Close examination of this data (apart from any data validation) will probably be carried out after using the design tools: For example, if the design tools recommend Natural Ventilation, then a next step would be to examine the typical speed and direction of the winds. These might help you to orient openings and decide if Cross Ventilation on its own is appropriate.
Weatool incorporates some standard passive design tools. In particular Bioclimatic Charts and Sun-Path diagrams.
The Bioclimatic chart (Psychrometry tab) uses the Psychrometric chart to plot values of temperature and humidity for a given period. These represent 2 of the main parameters affecting thermal comfort. By examining the concentration of these points, it is possible to determine the most likely successful technique for Cooling (and heating). These are techniques first set out by Olgyay and further developed by Milne and Givoni.
The path traced by the sun is represented in a Sun-Path diagram. This may be used to overlay radiation intensities and the effects of shading. The form of these sun-path diagrams is explained by consideration of the movement of the earth relative to the sun. This is explained in the presentation on Solar Geometry. Reading of the different Sun-Path diagrams and their use in shading analysis is also explained in the presentation.
Use of Sun-Path diagrams is further developed within Ecotect itself.