Heat Overlay Wizard (Heat Overlay)

How to set up the Heat Overlay Wizard

Generally, the steps required to use and configure the Heat Stress Overlay are as followed:

1. Determine the location and area of interest and generate a project for that area;
2. Add the Heat stress overlay;
3. Open the Heat stress overlay wizard to kick off the configuration process.
   1. Select date(s) and time of day
   2. Supply daily weather station data
   3. Supply hourly weather station data
   4. Select source for Foliage height

Date and time of day

1. Select a day for which you want to generate results. You can also choose to select multiple consecutive days when using the Heat Overlay Wizard.
2. Configure per day which hours you want to generate results for. Each day-hour combination will become a result. This result is stored as a time-frame to relate it back to the day and time.

Generated sun parameters

For each day, and for each time of day, the following will be automatically generated when using the wizard:

1. The day and time pairs, along with the project location, will be used to automatically calculate the sun altitude and azimuth angles for each day-time pair.
2. The sun daily motion factor is a parameter used in the atmospheric temperature formula. It will be automatically selected from the sun motion factor table, based on the date (column) and time of day (row).

Weather station data

Next, manually determine which weather station you want to use as a reference. Download the historical hourly weather data for that station and use the data from certain columns as input. In a nutshell, using the weather data, you have to supply:

• Daily Values

1. The minimum and maximum temperature of the day;
2. The average wind speed, measured at the height of 10 meters;
3. The average global sun radiation during sun hours;

• Hourly Values

1. The hourly temperature;
2. The hourly humidity;
3. The hourly sun radiation, as an average of the current and previous hour;
4. The hourly wind speed;
5. The hourly wind direction;

Foliage Height

Select what source will define the Foliage height:

• Buildings with functions related to foliage. The foliage height calculation model will determine the foliage height using the height of the vegetation (as buildings) and the foliage crown factor attribute;
• Areas with as foliage height attribute, defining the foliage height for a whole area;
• GeoTiff, defining a foliage height value for each cell in its raster.

Further reading

To read more documentation about the Heat Stress Overlay go to Heat_DPRA_Module