Location tab on model data at Site level
This data are defines the elevation of the site relative to sea level and is passed directly to EnergyPlus for use in pressure-related calculations. It is also used to calculate air density within DesignBuilder when calculating volumetric flow rates from cooling loads.
The site orientation is the angle of the site plan view relative to North. For example enter 45 to rotate the building(s) clockwise by 45°.relative to North (screenshot example below).
This is the quickest and most reliable way to rotate all the buildings on the site relative to North and allows you to keep your x and y axes aligned with the building. Rotating the building(s) is possible but once this is done it makes further geometric edits more difficult because, for rotations other than 90, 180 or 270°, the x and y axes will be out of alignment with the building.
North is indicated by the direction of the North arrow in the sketch plan view (above).
The exposure to wind model data affects the pressure coefficients used when the 'Calculated' Natural ventilation option is set. It also affects the calculation of U-values but these are not used in EnergyPlus simulations.
You can choose to add ground construction layers to any surface that is in contact with the ground. If you select this option you can define the construction layers of the ground.
Note: this option only affects the model for buildings having the Separate constructions model option set.
When the Add ground construction layers to surfaces in contact with ground option is selected you can define the construction layers to be added below any ground floor constructions and on the outside of any other surfaces which have been specified as being adjacent to ground.
More info on ground modelling.
The texture used to represent the ground in the rendered view on the Visualisation screen.
This field is a decimal number between 0.0 and 1.0 and is used to characterize the average reflectivity of the ground throughout the year. Ground reflectance data is used to calculate the ground reflected solar amount. This fractional amount is used in the following equation:
GroundReflectedSolar = (BeamSolar x COS(SunZenithAngle) + DiffuseSolar) x GroundReflectance
Important note on ground reflection
Reflection from the ground is calculated even if the Reflections option is not used, but if Reflections are not calculated the ground plane is considered unobstructed, i.e., the shadowing of the ground by the building itself or by component blocks is ignored.
Shadowing of the ground by component blocks is only taken into account if the Reflections option is used.
Conclusion: Switch Reflections on for accurate shading calculations.
A number between 0.0 and 10.0 which is used to modify the basic ground surface reflectance when snow is on the ground. Note that the value of GroundReflectanceUsed (below) must be <=1.
GroundReflectanceUsed = GroundReflectance x ModifierSnow
During simulations, the ground is considered to be snow-covered when the SnowDepth data in the hourly weather file is > 0.
A number between 0.0 and 10.0 which is used to modify the basic ground surface reflectance when snow is on the ground. Note that the value of DaylightingGroundReflectanceUsed (below) must be <=1.
DaylightingGroundReflectanceUsed = GroundReflectance x ModifierSnow
During simulations, the ground is considered to be snow-covered when the SnowDepth data in the hourly weather file is > 0.
There are 12 fields allowing you to represent the mean ground temperature for each month of the year. These temperatures are used as the outside surface temperature for all surfaces adjacent to ground.
Note that the depth at which these temperatures apply depends on the thickness of the ground construction (see above) added to the main floor/wall construction.
Caution: It may not be appropriate to use the 'undisturbed' ground temperatures calculated by the weather converter and listed in EnergyPlus hourly weather files as these values are too extreme for the soil under typical large conditioned buildings. A reasonable default value is 2°C less than the average monthly indoor space temperature is appropriate for such buildings. For smaller buildings, the ground temperatures will be closer to be undisturbed ground temperatures.
More information about determining appropriate ground temperatures is given in Ground Modelling and in the EnergyPlus Auxiliary Programs document.