Building Energy Software Tools
Formerly hosted by US Dept. of Energy    

Tas Engineering

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Tas is an industry-leading building modelling and simulation tool. Capable of performing fast dynamic thermal simulation for the world’s largest and most complex buildings, Tas allows designers to accurately predict energy consumption, CO2 emissions, operating costs and occupant comfort.

Tas is a complete solution for the thermal simulation of a building and a comprehensive tool for modelling plant and systems using it’s graphical and component based analysis. Tas is a powerful design tool in the optimisation of a buildings environmental, energy and comfort performance. Tas can import gbXML, INP, and IDF files from 3rd party programs. There are also customisable report generation facilities.

The Tas suite allows full automation available through visual basic. This enables quick parametric simulations to be carried out and allows you to make any changes to the model, export, simulate or extract results from any application within the Tas suite.

Tas simulations are multicore enabled, allowing users to simulate multiple buildings at the same time such as your UK building regulations Actual, Notional, and Reference buildings or your Appendix G ASHRAE 90.1 Proposed and 4 Baseline buildings all at the same time.

The Tas suite also comes with a host of utilities for regulatory analysis (UK Building Regulations Studio, ASHRAE 90.1 Studio etc.). Along with the regulatory studios Tas includes utilities for natural ventilation turrets, sun pipes, phase change materials amongst others. HVAC manufacturer data is also available in Tas Systems.

The Tas Suite includes the following applications:

  • Tas 3D Modeller (Geometry creation. Daylighting solution using radiosity and ray-tracing)
  • Tas Building Simulator (Building information modelling and simulation program)
  • Tas Results Viewer (Tabular, graphical and 3D results viewer)
  • Tas Systems (Plant and systems design and simulation program)
  • Tas Ambiens (2D CFD program, available as a separate program).

Consultancy services are available using our in house 3D CFD program which is not currently available in the release of Tas (Current release of Tas is version 9.4.3).

Tas 3D Modeller:

Tas 3D modeller allows you to trace out your floor plan using CAD drawings. As it isn’t a ‘volume modeller’ it allows quick adjustments to be made to the geometry. Building floors, building elements, windows, shades, and thermal zones are easily created and modified. Windows and shades can be grouped and applied to walls as one unit (only one window or shade type is needed for each different control strategy operating at the same time). Tas 3D modeller also allows the user to import gbXML files as well. The Tas gbXML import employs an intelligent healing feature that fills in the missing gaps in wall/ceilings etc. in the imported gbXML file and allows for surfaces to be corrected if imported with the wrong orientation. The Tas 3D modeller can perform daylight calculations based on radiosity calculations and is validated against international standards (CIE 171:2006). Daylight factors and lux levels can be displayed graphically on the floor plans to illustrate the calculated results. Daylight views can be rendered based on ray-tracing algorithms to show external and internal shading and to evaluate shading devices.

Tas Building Simulator and Tas Results Viewer:

Tas Building Simulator allows for detailed occupancy and use information to be built into your model as well as detailed natural ventilation controls. The Tas suite comes with comprehensive databases for Constructions, Internal Conditions (Internal Conditions include thermostat set up, infiltration and ventilation, occupancy, lighting, and equipment details for different space types such as an open office), Calendars, and Weather. Tas Building Simulator can handle large and complex buildings. Buildings of up to 4000 thermal zones have been simulated so far.

The Tas Results Viewer allows the user to display results in tabular, graphical, or 3D. The 3D view superimposes the chosen data onto the selected building geometry allowing you to step through hour by hour looking at your 3D model analysing anything from internal dry bulb temperature, internal solar radiation, aperture flow or any other data output.

Tas Systems:

Tas Systems uses component based plant simulation for the water and air side with advanced customisable control logic. Tas Systems can model all 8 of the 90.1 Baseline systems. Tas Systems includes the use of Modifiers which can use up to 3 dimensional tables or Linear to Tri-Linear, or Quadratic to Tri-Quadratic, or Cubic curve modifiers of plant components. Modifiers can use a multitude of different variables in the tables and curves. Tas Systems uses controller logic which is customisable using an advanced Lua scripting option where you can enter Lua code to customise the controller logic. Tas Systems also includes HVAC manufacturer data which can be imported into your HVAC components.

For a full list of up to date features visit our website:

Expertise Required: 

Qualified Engineer or Architect. Software include comprehensive tutorials. No training courses are required, although training is available.


Building services engineers and architects


A 3D CAD front-end allows building geometry to be input. Geometric data can be entered from other CAD packages. Comprehensive databases on thermal properties of materials, climate data, occupation schedules, and plant characteristics. A graphical interface makes for efficient data entry and modification.

Tas can import gbXML, INP, and IDF files from third-party programs.


Information is provided on comfort conditions, plant sizing, energy use and natural ventilation. There is also a CFD section of microclimate variation. There are pre-formatted inputs and outputs. All simulation data can be exported to other packages such as Microsoft Excel, Word, Publisher etc. for customised report preparation. However, Tas comes with a customisable report generator that includes the ability to incorporate your own name/logo.

  • Excellent responsive and accurate tool for concept development
  • Fast and robust tool with comprehensive capabilities for all types of energy modeling
  • Customisation and refinement of input data and highly customisable control of apertures, plant and systems.
United Kingdom
Major Capabilities: 
Whole-building Energy Simulation
HVAC System Selection and Sizing
Code Compliance
Building Type: 
whole building energy simulation
passive optimisation of buildings
daylighting simulation
thermal comfort
natural ventilation simulation
Free for Non-Commercial/Academic Use
Free To Try
Help and Support: 
Subscription Email Support
Subscription Phone Support
Last Software Update: 
24 May 2018
Last Entry Update: 
18 July 2018
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