For Engineers

Spend more time designing and less time modelling. An easy-to-use interface to accurately quantify performance in the fastest available workflow.

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For Architects

Fast, accurate modelling throughout the whole design process gives you confidence in your designs from concept to completion.

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For Energy Assessors

Confidently generate certificates and maximise QA audit success using the fastest and easiest software available.


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EnergyPlus is an extremely powerful simulation engine, but with DesignBuilder EnergyPlus you don't have to be an expert to use it. Let DesignBuilder do the hard work for you.

EnergyPlus Simulation key features

  • EnergyPlus is tightly integrated within this module providing advanced dynamic thermal simulation at sub-hourly timesteps.
  • Provide accurate environmental performance data such as energy consumption, carbon emissions, room comfort at annual, monthly, daily, hourly, and sub-hourly intervals.
  • Report solar gains on surfaces, surface temperatures and radiant exchanges.
  • Access an extensive range of results for buildings and systems.
  • Assess passive performance, thermal mass, and temperature distribution.
  • Export surface temperatures and airflow rates as boundary conditions for detailed CFD analysis.
  • Size heating and cooling systems.
  • Assess building operational and whole-life cycle costs using industry standard calculation methods.

Unparalleled Simulation Flexibility and Documentation

Most competing tools use a "black box" approach to simulation, meaning that you get no access to the raw simulation inputs, outputs and the code used to run the simulations, and so can never be really sure what is going on under the hood. DesignBuilder Simulations are different. With EnergyPlus you get full access to the source code and documentation which has been extensively tested by thousands of practitioners and academics. And when you need to model building facades, systems or operational modes that are not provided out of the box, you can  customise your simulations to match the real case through a range of methods:

  • Modify the simulation input files, either manually or automatically in a script (requires the Scripting module).
  • Customise the simulation using EMS runtime scripting (requires the Scripting module).
  • Modify the EnergyPlus source code (for the more confident modeller with software development experience).

No other mainstream simulation tool offers so much flexibility in an easy to use package.

Technical specifications

  • Calculate heating and cooling loads using the ASHRAE-approved 'Heat Balance' method implemented in EnergyPlus. Design weather data is included and loads can be reported at the zone, sytem and plant levels.
  • Run simulations of your model using real hourly weather data to check how the building would behave under actual operating conditions.
  • Daylighting - models lighting control systems using photoelectric sensors in the zone and calculates savings in electric lighting. Choose from stepped or continuous dimming.
  • Check the effects of design alternatives on the key design parameters such as annual energy consumption, overheating hours, CO2 emissions.
  • Energy consumption broken down by fuel and end-use.
  • Internal air, mean radiant and operative temperatures and humidity calculated.
  • An extensive range of comfort outputs are provided including underheating and overheating hours distribution curves, ASHRAE 55 comfort criteria, Fanger PMV, PPD, CIBSE TM52 and TM59, ASHRAE and CEN adaptive comfort metrics and unmet load hours. And with the addition of the Scripting module you can create your own comfort outputs.
  • Site weather data
  • Heat transmission through building fabric including walls, roofs, infiltration, ventilation etc.
  • Heating and cooling loads.
  • CO2 generation.
  • Environmental performance data is displayed without needing to run external modules or import data. Any simulations required to generate the data are started automatically.
  • HVAC can be simulated using either Simple or Detailed options. Detailed requires the HVAC module
  • DHW
  • Natural ventilation can be modelled with the option for windows to open based on control schemes including mixed mode.
  • Glazing systems including frames, dividers and reveals are modelled in great detail using the most accurate simulation algorithms available. Innovative facade systems such as electrochromic glazing, transparent insulation and MicroLouvres can be simulated.
  • Shading by louvres, overhangs and sidefins as well as internal and mid-pane blinds.
  • Model glazed cavities such as double facades and Trombe walls.
  • Dynamically varying vertical temperature gradients in tall spaces such as atria and for displacement ventilation systems.
  • Architectural features such as columns, awnings and complex shading devices can be treated including the effect of shading and reflection.
  • Parametric analysis screens allow you to investigate the effect of variations in design parameters on a range of performance criteria.
  • The Simulation Manager allows you to run and control multiple simulations and view their results. Simulations can be run in parallel on the local machine or on a simulation server on the network. This allows a large number of simulations to be queued and run overnight and results picked up and analysed in the morning.
  • Choose from a range of different EnergyPlus simulators including the current DOE executable release, the current DLL release and any interim releases made available by DOE. You can even access versions of EnergyPlus you have compiled yourself.
  • EnergyPlus allows you to calculate energy and carbon savings through control of electric lights according to the availability of natural daylight. The daylight illuminance levels in a building depends on many factors, including sky condition, sun position, photocell sensor positions, location, size, and glass transmittance of windows, window shades and reflectance of interior surfaces. Reduction of electric lighting is calculated based on daylight illuminance level, illuminance set point, fraction of zone controlled and type of lighting control.

Example results viewer outputResults Viewer

The Results Viewer can be used to view results contained within EnergyPlus output files and compare with results from previous simulations. It allows any of the thousands of data reports that can be generated by EnergyPlus to be viewed alongside results from the same or previous simulations. When used for analysing detailed HVAC node conditions it can be a valuable tool to help understand HVAC system operation (see a sample of graphic output to the right). 

Packages including EnergyPlus Simulation

Simulation is core functionality for most DesignBuilder applications and is is included in Energy Assessor Plus and all Architectural and Engineering packages

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Find out for yourself why so many companies and universities choose DesignBuilder

Case Studies

Trusted by many of the world’s most prestigious companies and universities

  • "I have watched the steady progression of DesignBuilder for the last 10 years or so, and having seen recent improvements in DesignBuilder’s HVAC and LEED modeling I decided to attend their training. I was both surprised and pleased to find how easy to use DesignBuilder is compared to the other similar tools I’ve tried, especially given the power and flexibility offered by the underlying EnergyPlus, Radiance and CFD engines. I’m really pleased that after a week’s training I feel ready to produce accurate results and outputs for loads and sizing calculations and energy analysis. The ability to also undertake fully-integrated daylighting and CFD analysis from the same model you use for loads and thermal simulations is also a very big plus point."
    David Ellis PE, Virginia 22102, USA
  • " We have had a very positive experience with DesignBuilder this semester as it was the first year we shifted from our previous simulation software to DesignBuilder. Our students seem to spend less time on learning the software and more on actually understanding the results and being able to analyse them."
    Dr Shahaboddin Resalati - Senior Lecturer in Sustainable Architecture and Building Physics Architectural Engineering Group, School of Architecture, Oxford Brookes University, UK
  • " The graphical user interface of DesignBuilder is comprehensive and intuitive, allowing us to model complex buildings simply and quickly. The data management structure (data hierarchy and inheritance) allows us to assign model data quickly and accurately, improving our efficiency. The power and flexibility of EnergyPlus, the underlying simulation engine, enables us to model a building in fine detail where required so that we can accurately analyse its performance. This is particularly helpful when calibrating the model with actual energy consumption to obtain a reliable close match when assessing potential improvements and energy conservation measures."
    Alessandro Righi, architect and researcher at IUAV - Laboratory technical physics
  • " We utilised DesignBuilder software to carry out detailed natural ventilation assessments on buildings at our UK gas plants in order to demonstrate compliance with hazardous area regulations. First of all I would like to praise the initial support received from DesignBuilder staff, who were extremely knowledgeable and provided a welcoming point of contact for support and advice. Having used the majority of the alternative building simulation software packages on the market, I found without a doubt DesignBuilder the most user friendly and enjoyable to use. The modelling program itself is fantastically simple allowing even complex buildings to be developed quickly and easily. The user interface of the calculation part of the software is well thought out and the results outputs are graphical and concise. Within a few hours I had got to grips with the software and obtained the results I desired. It has allowed Shell to present compliance to regulating authorities, who were also impressed with the visualisation displays and graphical outputs. I fully endorse DesignBuilder, and in particular how easy it was to learn and use compared to similar building simulation software on the market. "
    Iain Begg, Senior HVAC Engineer, Shell Projects and Technology Group, Aberdeen, Scotland
  • " DesignBuilder’s clear, well-structured layout and intuitive help system makes it a much simpler tool to learn and use, and compared to other simulation packages the creation of professional-looking geometry is much easier. The ease of use extends to other areas of the program such as thermal bridging analysis and setting up HVAC systems, and the capability to easily model adjacent ground conditions is very useful. A very important aspect of our work is optimisation, and DesignBuilder seems to be the only software that currently provides this functionality. We are encouraged that the development team have taken some of our functionality and user efficiency suggestions on board for the next release. We are already using DesignBuilder for research, and for the above reasons we think it is a tool that our students will find easier to use so we will be using it for teaching next academic year. "
    Professor Ljubomir Jankovic, Birmingham School of Architecture, Birmingham City University
  • " We decided to go out and measure some natural light levels in buildings that we have access to.... One building was our own office, and the other was a green building we worked on which will be tenanted in 2 weeks so we had a chance to take readings in the same environment for which we simulated. I am happy to say that the DesignBuilder results are very close to what we measured... What impresses me is that if we measure a value of 250 lux at 3m from the facade, DB returns similar values. This means that if we say that 40% of a building's usable area will have lux levels of 250 or above, then the measured results correlate with that. ... It certainly makes us confident in the results we give to clients."
    Warren Gray, Mechanical Engineer, Solid Green Consulting
  • " First of all I would like to thank you very much for the outstanding online training that you made possible for our team. I was very happy that we could join with three people in an online training that offered us as an outstanding value. ... The course with DesignBuilder is going very well and we have some great feedback from the students.... Your data entry GUI makes it easy for students not only to “accept defaults” but to experiment. In addition your online help is extremely thorough and you present not only the theoretical background but also offer great links to the reference. You might not realize what a powerful learning tool this is; but it is. We think you have created something very valuable and we are looking forward very much to where your company goes from here... Thanks again for your great support."
    Dr Manfred J. Zapka, University of Hawaii
  • " Gold stars all round .... Many thanks again for the high quality of customer service I receive from all at DesignBuilder, it is quite refreshing and a credit to your company."
    Mark O’Neill, DM Hall LLP, Glasgow, Scotland

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