• Multiple zone dynamic heat balance, including specific contributions from: sun, occupants, equipment, lights, ventilation, heating and cooling devices, surface transmissions, air leakage, cold bridges and internal objects such as furniture.
• Solar influx through windows with full account for local shading devices as well as surrounding buildings and other objects. Detailed 3D direct and diffuse shading calculations.
• Air and surface temperatures
• Operating temperature at multiple arbitrary occupant locations, e.g., in the proximity of hot or cold surfaces. Full non-linear Stephan-Bolzmann radiation with view factors is used to calculate radiation exchange between surfaces.
• Non-linear correlations for film coefficients
• Directed operative temperatures for estimation of asymmetric comfort conditions
• Comfort indices, PPD and PMV, at multiple arbitrary occupant locations
• Daylight level at an arbitrary room location
• Zone CO2 and moisture levels, both of which may be used for control of VAV system air flow
• A model for vertical air gradient calculation is available
• Wind and buoyancy driven airflows through leaks and openings via a fully integrated airflow network model. This enables study of, e.g., temporarily open windows or doors between rooms.
• Airflow, temperature, moisture, CO2 and pressure at arbitrary locations of the air handling and distribution systems
• Power levels and temperatures for primary and secondary system components
• Total energy cost based on time-dependent prices as well detailed energy accounts

Reports

Special reports are available for single page printout of key output summaries of, e.g., monthly energy totals over the year including energy cost or zone climate summary over a day. All reports and diagrams can be automatically exported into a formatted Word document, with editable (emf-format) diagrams.

Input parameters are grouped into objects, which are chosen from a database. Geometrical input is configured in graphical editors. All geometrical data can be specified graphically as well as numerically.

Models can be automatically built based on 3D CAD data in the industry standard IFC format, which can be generated from most CAD tools such as AutoCAD ADT, ArchiCAD, Microsoft Visio, Facility and others. Geometry of zones, walls, windows and openings are directly imported as well as any available wall and window constructions.

Extensive hourly climate data as well as design day data is available for downloading from the ICE User’s website for many European and international locations. An open source weather file utility enables conversion from the most common data formats.

A single zone ICE model with default primary and secondary systems comprise a total of about 600 time dependent variables, any of which may be plotted. The most common output requests are easily selected, while more sophisticated options require some navigation in the mathematical models.

Memory requirements and execution time

Available memory sets the limit to the size of problems. A large model may have perhaps 50 zones but considerably larger models have been simulated on less than 128 Mb memory.

Execution time is highly dependent on model structure and control. The full system of equations is solved with the general purpose, variable timestep IDA Solver. A standard yearly simulation of a ten zone model takes about five minutes on a modern PC. All problem variables are then solved with a time resolution of less than a few minutes. This resolution enables study of detailed control behavior in a full-building context.

Any variable may be plotted with this time resolution. Alternatively, hourly, daily, weekly or monthly averages are presented as graphs or tabulated in a text window. Output signals may also be converted into duration form over arbitrary time intervals. A special function enables export of equidistant time series to Microsoft Excel.

Since IDA ICE is built with IDA Simulation Environment, mathematical models may be re-connected arbitrarily by the end user. This is particularly useful for configuration of non-standard system types. Available building material for this type of work is first of all the native ICE library of some seventy NMF models. Also directly compatible is the ASHRAE toolkit for secondary systems and a full library of multizone airflow models.

A year’s worth of temperature data shown in the Swedish
user interface. ICE is available in English, German,
Swedish, Finnish and Norwegian. The red curve
represents air temperature while the blue shows
operative temperature in the middle of the room.
The setpoint for the (somewhat undersized) chilled
beam PI controller is 25 ºC.
Same temperatures as in the previous image but here
presented as a duration diagram for the occupied periods
only. The number of hours with too low and high
temperatures can easily be estimated.
The zone heat balance for a day of overheating. The heat
balance often gives good advice as to the cause of a
problem (here high solar influx).


ICE is capable of representing also fast control
response with good accuracy. Here, a two-point
thermostat controls air temperature, setpoint=20 ºC,
dead band= 1 ºC.


Using NMF and IDA Simulation Environment, most
phenomena in conjunction with the building can be
modeled. The image shows the results from a 3D solution
of the heat equation under a building after some six
months of simulation.

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