Design buildings your way

Building energy modeling software
for busy consulting engineers


New Tas Release

Download Tas to start using the new features or request a trial


Free Tas training course

Video and workbook based courses provide clear, step-by-step guidance


Free Tas Licenses for academic use

We have made Tas available for academic use at no charge. Augmented with a free Tas Course.

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Tas Features

Learn to use Tas

Technical Briefings

Tas Engineering_Simple

With Tas Engineering you can:

  • Create 3D geometry
  • Import/ export BIM file formats
  • Perform daylight and climate based daylight modeling analysis
  • Simulate building loads
  • Create component based HVAC air and water side systems
  • Simulate HVAC for sizing/ energy/ cost/ CO2
  • Easily access and visualize all simulation data
  • Switch between IP and SI units with the click of a button

Scroll down to see more of Tas Engineering

HVAC simulation using Tas Systems

Component Based

Tas Systems is a Component based plant modeling tool with a drag and drop interface.

Fully Customizable

Every component has editable properties with fully customizable control logic.

Schematic Design

Plant models are laid out to resemble HVAC schematics for clarity.

Template Systems

Optional wizard to walk users through setting up common system types.

Easy data exploration for QA/QC and system behavior analysis

Reports can be easily generated as PDFs or Excel spreadsheets. The report generator is a great way for the user to extract the desired results in an easily interpreted and accessible format over the time period of interest, be that annual, monthly, daily or hourly.

Co-ordinate your project

Tas Systems is fully integrated with the other components of the Tas package and results can be imported from multiple simulation files.  This allows engineers to work concurrently on different parts of the building then merge their results together to work on the HVAC.


140-1 compliant software for 90.1 versions 2007-2016


Tas Engineering includes a 90.1 studio which does all the hard work for you, generating baseline building geometry and lighting gains for 90.1 versions 2007, 2010, 2013, and 2016 as well as providing tools for calculating efficiencies for baseline equipment based on sized capacity, fuel type, climate zone, etc. 


Tas is compliant with ASHRAE 140-1 2014, 2007, and 2004, as well as being a qualified 179D software for Tax deductions.

Daylight Simulations

Climate Based Daylight Modeling

Multi-core distributed Climate Based Daylight Modeling for rapid design iterations.

Daylight Factors

Fast daylight factor calculations using a radiosity engine for accurate results.

Daylight Rendering

Render a high quality raytracing based 3D view of your building at any hour of the year for shading and shadow casting analysis.

Right to Light

Equivalent First Zone, Daylight Distribution, Vertical Sky Component, Permanent Overshadowing.

Tas Generic Optimization

A utility for parametric simulations & variable optimization

TasGenOpt intelligently combines GenOpt from Lawrence Berkeley National Laboratory with a powerful c# scripting interface in order to achieve incredible flexibility and design options. This utility allows parametric analysis as well as an optimization facility

Optimization and Parametric Analysis

Sometimes, it’s easy to understand the effect of a variable on your building: Increasing the boiler efficiency results in a reduction in CO2 emissions. Other times, it’s not so clear.

Imagine adding more insulation to your external walls – the U-value will decrease and the heating demand will decrease, but this may have some other effects:

  • Increased risk of overheating
  • Increased cooling demand

With some variables, there is an optimum value that balances the effects a variable has. One way to find this optimum value is to perform many simulations with different values, but this can be slow and time consuming. 

TasGenOpt solves this problem by doing the hard work for you, automatically minimizing the number of simulations required to find the optimum value through parametric analysis.

Comfort Analysis

Assess the expected comfort levels in your design

Data Import & Export

Tas has a multitude of data import & export options enabling it to be an integral part of a BIM workflow.


2D DWG import allows tracing of new geometry, and 3D DWG shade surface import allows easy modeling of complex shading.


Tas intelligently repairs common issues with gbXML geometry.


Exchange data with EnergyPlus. Import or export geometry, building fabric, gains and schedules, and even import shading data for a ready-to-simulate building data file.​


Import geometry, building fabric, and internal condition data from DOE-2 INP files.

SI & IP Units – Its just a simple switch between units of measurement

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