Location

This dialog describes an object of the Location type. It contains the geographical position and references to weather data for the place where the simulated building is located. The Location can be set manually, selected from the loaded database or downloaded in the general tab.  

There are three different types of weather data involved:

1. Weather data for statistically determined extremely hot or cold so called design days that are used for sizing of cooling or heating loads. This data is taken from an ASHRAE database, which has been documented in ASHRAE Fundamentals 2021, Chapter 14.
2. User-defined design day data. A simplified version of design day data that can be entered by the user. This simplified data is also used to accommodate design-day data from previous versions of IDA ICE.
3. Yearly measured climate data for whole-year simulations. This data should reflect normal, often hourly, weather conditions that should be applied to compute energy use. Extreme periods might occur, but their statistical significance for sizing is not reliable.

The given design day data is used when synthetic weather has been selected in Heating or Cooling load calculations. This data is also used for Custom simulations when the Synthetic (winter or summer) option has been selected in the Climate field in the building form

Field descriptions, etc:

Location: Choice of location. The rest of the dialog shows the details of the selected location.

Position: Country country or geographical area for calculation

Position: City place for calculation

Position: Latitude calculation object’s latitude (Deg). To avoid sign confusion, the directions from equator are denoted by N (north) and S (south)

Position: Longitude calculations object’s longitude (Deg). To avoid sign confusion, the directions from Greenwich are denoted by E (east) and W (west)

Position: Elevation calculation object’s height over sea level (m)

Position: Time zone calculation object’s time zone (h). To avoid sign confusion, the directions from Greenwich are denoted by E (east) and W (west), e.g. 1 E for Central Europe.

Climate description Default climate file for given location

Design day data: Design data file Reference to the ASHRAE database file for the location¹

Design day data: Button "User-defined design days" Press this to provide your own design data for a single hot or cold day. Once pressed, you can only revert by cancelling the dialog and starting over. ¹

Design day data: Dry-bulb min Lowest dry bulb temperature during the day (°C) ^1,2

Design day data: Dry-bulb max Highest dry bulb temperature during the day. (°C) ^1,2

Design day data: Wet-bulb max Highest wet bulb temperature during the day. (°C) ^1,2

Design day data: Wind direction The wind is only relevant to the airflow through the building if pressure coefficients are given and more than one leak or opening has been defined. (Deg)
The wind from North has direction 0°, from East 90°, etc. ^1,2

Design day data: Wind speed Wind direction and speed is kept constant during the day (m/s) ^1,2

Design day data: Clear-sky-optical depth, tau_b Empirical parameter for sky optical properties. ¹

Design day data: Clear-sky-optical depth, tau_d Empirical parameter for sky optical properties. ¹

Design day data: Clearness number Reduction factor for direct and diffuse sunlight. 0 = dark, 1 = clear, dry and cloudless atmosphere, 1.15 = extremely clear conditions.  ²

¹ Field is displayed when ASHRAE design data has been selected.
² Field is displayed when user-defined design data has been selected

Object: name and description

For ASHRAE cooling design data, weather parameters are available for each month of the year. Cooling load design temperatures are given at four levels of statistical severity: 0.4, 2, 5, and 10% monthly cumulative frequency for the dry bulb temperature. By default 2% is set, corresponding to that the outdoor air temperature exceeds this temperature around 15 h during the month in average. The data for the hottest month are shown for reference. Other levels can be selected in the Cooling load setup dialog. For winter data, the level for a yearly cumulative frequency of 99.6% for the dry bulb temperature is shown, and these data are used for the heating load calculations. This corresponds to that the outdoor air temperature goes below this temperature in average around 35 h in a year. 

When ASHRAE design data is used, the temperature variation over the day and the sky optical properties are given by the model described in ASHRAE Fundamentals 2021, Chapters 14.4 and 14.2.

For user-defined synthetic climate, a simpler sky model is used, where a Clearness number gives the presence of clouds or unclear atmospheric conditions. For a clear, dry and cloudless sky, 1 is given. A normal daily average for a clear day summer day can be 0.8. Under extremely clear conditions, particularly in northern countries, 1.15 may occur. Further information about clearness number and additional references can be found in e.g. ASHRAE Fundamentals 2005, Chapter 31.