System parameters

Degree of automatic
schedule smoothing

It smoothes the schedule signals for internal gains, which are occupants, equipments and lights.

The parameter will be set for each of those schedules:

The same schedule without smoothing will be created to indicate the time when a zone is "in use":

This can also be overwritten within each simulation setup.

This parameter is used only for zones where ventilation system "VAV, temp. control" or "VAV, temp+CO2 control" is selected. It then sets the cooling setpoint to Setpoint + Offset for water-based cooling units in these zones.

A positive value means that the setpoint for water based cooling is increased and air cooling system will be used first, with water cooling activating only later, if air based cooling is not sufficient.

The offset thus determines how much the temperature needs to rise before the water cooling system engages.

This parameter is used only for windows where "Sun" is selected for integrated or external window shading control. It then defines the solar radiation level at or above which the shading is activated.

Note: In the case of integrated window shading, this solar radiation can be measured either inside or outside of the window. This is defined by the next system parameter.

This parameter is used only for windows where "Sun" is selected for integrated window shading control. It then indicates whether solar radiation for shading control (see previous system parameter) is measured inside or outside of the window surface.

Note: The radiation for shading control is always measured as if the shading was not drawn.

Parameter "sensorSide" of the Window model is set to "FRONT" for outside and "BACK" for inside measuring.

This parmater is used only for windows where "Sun" is selected for integrated window shading control. It then defines the angle between the direction normal to the window surface and the sun position, at or below which the shading is activated.

The default value of 90 ° means, that the sun must be directly visible by the window, to activate the shading. If also direct radiation above threshold should activate the shading, this parameter need to be set to 180 °.

Used only for occupants that can adapt their clothing:

Parameters hi and lo of this controller:

Method for measurement of daylight level

&

Height above floor for daylight calculation plane 'Average over floor'

In IDA ICE, for all zones the daylight hits all zone surfaces from where it is diffusively reflected once. Daylight is then measured on one single measuring plane that "sees" all windows and reflecting surfaces. This system parameter defines for all zones, where this daylight measuring plane is located.

The measured daylight lux level is on the one hand shown in the "Daylight diagram" and on the other hand used for all predefined or userdefined controls that use daylight measurement.

Note: The daylight measuring plane for the IDA ICE lux calculation is not the same as the measuring planes for Radiance calculation, that are editable by the user and visible in the 3D view. They always face upwards and connot be visualized.

The light distribution to all surfaces (including the daylight measuring plane) is given by the parameter vector "surfCoef" of light distribution models for each window:

IDA ICE calculates all air with the concentration of one pollutant, that by default is CO₂. The CO₂ concentration in the zones or zone layers is calculated through mass balances due to ventilation and infiltration rates, as well as internal sources from occupants and optionally sources or sinks from equipments.

Note: One could also interpret all variables of the CO₂ concentration as a concentration of another pollutant, if one adjusts the anbuebt air "CO₂ level" accordingly and makes sure that there are no occupants in the model.

The ambient air CO₂ level is defined as a binding to the variable "XAir" in the climate processor.

Note: As the average molar mass of air is 28.96, while of CO₂ it is 44.00, we can observe a factor of 44/28.96 = 1.519 between the volume-specific concentration of the system parameter and the mass-specific concentration XAir in the climate processor.

This parameter specifies the exponent used in the leak power law when the Estimated Leakage Area (ELA) is provided in the zone model. It determines the relationship between pressure and leakage rate.

Note: The ELA is defined in the ventilation section of the zone, measured in m². A yellow background indicates a variation from the default values.

For each zone, the parameter, "N", in the CELEAK element represents the exponent in the power law.

The Cd factor, or discharge coefficient, characterizes the efficiency of airflow through an opening. It takes into account various factors affecting airflow, including friction, turbulence, and the geometry of the opening.

Note: A higher Cd value indicates less resistance and more efficient airflow, while a lower Cd value suggests greater resistance and reduced airflow.

For windows, the parameter is available in the openings section under "More...". For doors, it can be found in the general settings.

Note: A gray background indicates the use of the default value defined in the system parameters.

This parameter includes the effect of solar radiation absorbed by an occupant or a sensor when calculating the operative temperature. The effect of direct and diffuse solar radiation is added to the thermal radiation from the walls when the mean radiant temperature is calculated. An absorption factor of 0.85 is used, but can be changed at advanced level. Emissivity is approximated to one. The calculation method is described in “A model for managing and evaluating solar radiation for indoor thermal comfort" by La Gennusa et al., Solar Energy 81 (2007) 594–606. The parameter is by default set off.

This parameter is valid only for zones using the Climate zone model (with or without stratification), where it affects the operative temperature and thereby the PMV/PPD values. It also affects the distribution of heat from the occupant(s) between thermal radiation, convection and vaporization, and thereby the heat balance in the room. It does not affect the directed operative temperature.

This parameter affects the thermal balance between surfaces and the air mass in a zone, i.e. both temperatures and heat flows are affected. The heat flow from and to the air mass is evenly distributed.

This parameter specifies the duration of the sliding average applied in post-processing signals, helping to smooth out fluctuations in the data over time.

By default, this interval is set to 15 minutes, providing a more stable representation of the information. This method ensures that measurements, such as maximum and minimum peak values, are not viewed as instantaneous values but instead reflect a more accurate average over the specified time period.

This parameter influences the generated post-processing signals used for diagrams, reports, and tables at both the zone and building levels that utilize a sliding average. The interval for all sliding averages is set to this value, ensuring consistency across the analyses and representations of data.

Note: A green background indicates the use of the default value defined in the system parameters. A yellow indicates a variation from the default values.

These parameters indicate  threshold values for the operative temperature.

It is used to calculate the number of hours that exceed these thresholds, which are displayed in the Summary table under the lower level and higher level columns. 

The total number of hours exceeding these thresholds is available in the Summary table under the columns labeled

"h of T_op > X, h"

for each zone in both the Energy and Custom simulations.

For each zone, the post-processing components — sliding average (DIFF_COOL/HEAT_AVG) and duration (UNMET_COOL/HEAT) — are utilized for calculations.

The temperature tolerance is input for the sliding average component, along with the indoor air temperature and the setpoint.