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, and allows designers to accurately simulate daylighting and 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 HVAC 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 has a two-way link to EnergyPlus and EnergyPlus based tools via IDF, and can also import gbXML and INP from 3rd party programs. There are also customizable report generation facilities.
Tas is accessible through its fully open API. This enables users to create automated worksflows, for example, quick parametric simulations can be carried out, The automation interface (VB.NET, C#, VBA) allows you to make custom changes, such as: manipulating model inputs, creating new geometry, import/export data, simulate files, extract results data etc. from any application within Tas.
Tas simulations are multicore enabled, allowing users to simulate multiple buildings at the same time. Meaning Appendix G ASHRAE 90.1 Proposed and 4 Baseline buildings can all be simulated at the same time or UK building regulations Actual, Notional, and Reference buildings. The Climate Based Daylight Modeling feature of Tas is also multi-core enabled, however it also allows the CBDM simulation to be run across multiple computers on the same network using peer-to-peer technology, leveraging the processing capabilities of multiple machines at the same time for fast simulation.
Tas 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 and can easily be incorporated.
Tas 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 of building loads)
  • Tas Systems (HVAC design and simulation program. Simultaneous graphical, tabular, and psychrometric chart data display possible)
  • Tas Ambiens (2D CFD 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 9.5 (01/01/2020).
Tas 3D Modeller:
Tas 3D modeller allows you to trace out your floor plan using CAD drawings. Building stories, building elements, windows, shades, and thermal zones are easily created and modified. 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 (free training available here: The Tas 3D modeller can perform climate based daylight modelling and point-in-time daylight calculations based on radiosity calculations and is validated against international standards (CIE 171:2006), and has been successfully benchmarked against Radiance. Daylight factors and lux levels can be displayed graphically on the floor plans or in 3D 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. Daylight Autonomy and UDI metrics can be calculated to comply with LEED and the UK Priority Schools Building Program.
Tas Building Simulator and Tas Results Viewer:
Tas Building Simulator allows for detailed occupancy and use information to be built into your model, detailed natural ventilation controls and analysis of passive solar heating and solar shading concepts can be analyzed easily. 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), Calendars, and Weather. The International Glazing Database, COMNET, ASHRAE 90.1, and UK Building Regs databases are included. Weather databases are also included however, weather data can be imported from .epw files. (Sourced from the Department of Energy website). Tas Building simulator is perfectly placed for quick analysis of simple box models and early designs with extremely fast simulation times to allow rapid feedback and model QA and QC procedures. As Tas Building Simulator can handle large and complex buildings your model can progress in one platform as you move through simple box models, to schematic design (SD), design development (DD), and construction documents (CD). Resulting in 'as built' performance models with the possibility of post occupancy analysis. Buildings of up to 4000 thermal zones have been simulated.
The Tas Results Viewer allows the user to display results in tabular, graphical, or 3D formats with all data types easily exported (to excel for data or to high res images for graphical content) to be used in creating your own custom reports and graphical content to communicate the data effectively. The 3D view superimposes 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 for the zone, down to data for individual surfaces (temperature, solar gain, internal condensation etc.).
Tas Systems:
Tas Systems uses component based HVAC simulation for the water and air side with advanced customisable control logic. Tas Systems can model all 90.1 Baseline systems (2007 - 2016). Tas Systems includes the use of Modifiers which can easily model manufacturer level detail for components. Simple COPs and efficiencies with part load can be included as well as using, for example, 3 dimensional tables or Linear to Tri-Linear, or Quadratic to Tri-Quadratic, or Cubic curve modifiers of HVAC 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 allowing users to customise the controller logic. Tas Systems also includes HVAC manufacturer data which can be imported into your HVAC components. Tas Systems visually communicates flow rate, temperature, and pressure simulation results on the schematic diagram. It allows users to see tabular, graphical, and psychrometric data simultaneously (if desired) to understand how a schematic is performing for easy QA and QC procedures (see video below).
For a full list of up to date features visit our website:

Tas Systems - interactive visual results exploration

Expertise Required: 

Qualified Engineer or Architect. Software includes comprehensive tutorials. No training courses are required. FREE training material is available online:


Consulting engineers and architects


A 3D CAD front-end allows building geometry to be drawn. Geometric data can be imported from other CAD packages. Comprehensive databases on thermal properties of materials, climate data, occupation schedules, internal heat gains, and HVAC characteristics are included to be used for inputs. A graphical interface makes for efficient data entry and modification.
Tas can import  RevitTM (gbXML), EnergyPlus and EnergyPlus based tools (IDF), and eQuest/DOE2 (INP) files


Information is provided on building loads, HVAC sizing, energy use, comfort conditions, and natural ventilation. There are pre-formatted inputs and outputs reports. All simulation data can be exported to other packages such as Microsoft Excel, Word, Adobe products etc. for customized report preparation. However, Tas comes with a customizable report generator that includes the ability to incorporate your own name/logo. Tas can also output data to be read into EnergyPlus based tools. Please see the Technical Briefings for examples:

  • Whole-building Energy Simulation and Performance Analysis
  • Load Calculations and Load Reduction Analysis
  • HVAC System Selection and Sizing (Template HVAC systems can be used to test HVAC system options)
  • Parametrics and Optimisation using TasGenOpt
  • Energy Conservation Measure Analysis
  • Code Compliance (90.1, UK Building regs (Part L & EPC), can be used as part of Title 24)
  • Utility Bill and Meter Data Analysis for detailed cost analysis
  • Weather Data and Climate Analysis - annual inslolation and annual sun availability analysis
  • Lighting Simulation - CBMD and Point-in-time Daylighting Calculations (UDIx metrics, lux, Daylight Autonomy (DA), Daylight Factors, Rendered lux views etc.)
  • Air Flow Simulation - natural ventilation simlation for load reduction (complex multi-zone displacement, stack, cross, and single sided ventilation simulation etc.)
  • Detailed Component Simulation - component based HVAC systems allows detailed and custom component simulation
  • Solar and Photovoltaic Analysis
  • Wind turbine Analysis
  • Building Simulation data driven 2D CFD analysis for detailed thermal comfort analysis
  • Support and Training services available - [email protected] /
United Kingdom, United States, Australia
Major Capabilities: 
Whole Building Energy Simulation
Load Calculations
HVAC System Selection and Sizing
Parametrics and Optimization
Code Compliance
Building Type: 
Multi Family
District Scale
whole building energy simulation
passive optimisation of buildings
daylighting simulation
code compliance
Free for Non-Commercial/Academic Use
Free To Try
Help and Support: 
Subscription Email Support
Subscription Phone Support
Last Software Update: 
01 January 2020
Last Entry Update: 
14 January 2020
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