Green Building Studio's interface relays estimated HVAC costs.
Michael Kilkelly Green Building Studio's interface relays estimated HVAC costs.

A new round of simulation tools puts the power of building-performance analysis—long the domain of engineers and energy consultants—into the hands of architects. According to the AIA’s Energy Modeling Practice Guide, architects are the most qualified members of the project team to lead the energy-modeling process, given their expertise in integrating program, space, and building systems.

Predicting a building's post-occupancy performance early in the design process gives teams the greatest opportunities to optimize a project and understand which decisions will have a significant impact on carbon footprint. Generally speaking, tools that provide real-time feedback and order-of-magnitude comparisons are best suited for the conceptual and schematic design phases, given the rate of design changes. In later phases of the design process, accuracy takes precedence over immediacy as a building becomes more defined.

In the past, designers seeking performance-analysis software had to sacrifice accuracy for ease of use. High-end simulation engines, such as DOE-2.2 and EnergyPlus, required a lot of detailed information and time to compute—two things that are in short supply in the early design phases. Recognizing these constraints, several software companies have developed tools and plug-ins that integrate almost seamlessly into existing BIM software and facilitate early-and-often checks on building performance. Below are five such products to consider for your next project.

Vabi Apps, by Vabi Software
Works with: Autodesk Revit
Cost: $9.99 to $29.99 a month
Vabi Software provides a suite of apps for calculating and visualizing a project’s environmental, financial, and programmatic performance. The Thermal Comfort Optimizer calculates ideal heating and cooling set points for each room in a building, while the Daylight Ratio Evaluator calculates the amount of daylight a space is receiving and highlights rooms that do not meet requirements. The Energy Assessor, which is forthcoming, estimates the project’s monthly and yearly energy use and costs.

Results from all of the developer's apps are summarized on a single interface, Vabi's building performance dashboard, which tallies an overall score based on each criteria for a project. While Vabi Apps do not provide as much detail as some of the other products listed here, their affordability and ease of use are a plus.

Sefaira Architecture, by Sefaira
Works with: Autodesk Revit and Trimble SketchUp
Cost: Varies depending on product package. Contact for more information. 
Sefaira provides interactive building-performance feedback through its Sefaira Architecture plug-in, which calculates and graphically displays metrics, including daylighting factors, energy use intensity, and energy use breakdown by building system, in real-time on a performance dashboard.

The Element Performance chart, which is integrated into the dashboard for convenient access, offers more in-depth insights on how building components, such as walls and windows, affect overall heating and cooling loads. The Daylighting Visualization tool shows the distribution of natural light throughout the building. Similarly, the Direct Sunlight Analysis tool quantifies the amount of direct sunlight each space receives throughout the day, a metric used in certification programs such as Australia’s SEPP 65 program and the BREEAM system, which is popular in the U.K.

Sefaira’s Web app, which uses the cloud to process and analyze models with the EnergyPlus simulation engine, provides a faster and more in-depth analysis of the building model while allowing for straightforward comparisons between design options.

Sefaira's Daylighting Visualization tool
Sefaira Sefaira's Daylighting Visualization tool

Green Building Studio, by Autodesk

Works with: Autodesk Revit and any modeling software that exports to gbXML
Cost: Part of the Autodesk Subscription program
Green Building Studio (GBS) is available as a standalone cloud-based service or as part of Revit’s add-on Energy Analysis tools. Using the DOE-2.2 analysis engine, this service provides a very detailed analysis and, as a cloud service, runs quickly on Autodesk’s servers.

Ordinarily, the DOE-2.2 engine requires a thorough description of a building’s envelope and mechanical systems. However, GBS makes assumptions for many of these parameters using ASHRAE standards, allowing architects to focus on the design areas that have the most significance on the building’s overall energy footprint without getting bogged down in technical details. In addition to calculating energy consumption, electricity use, and annual carbon emissions, GBS also estimates the building’s Energy Star score, points for glazing factor and water credits for the U.S. Green Building Council's LEED rating system, and solar energy potential.

One downside to the cloud-based approach is that the analysis is provided in a report format rather than interactively in the model itself. However, the GBS report viewer does allow for side-by-side comparisons of simulation results.

Green Building Studio estimates a project's heating and cooling loads.
Michael Kilkelly Green Building Studio estimates a project's heating and cooling loads.
Green Building Studio breaks down several building performance metrics.
Michael Kilkelly Green Building Studio breaks down several building performance metrics.

OpenStudio, by the National Renewable Energy Laboratory

Works with: Trimble SketchUp
Cost: Free
Available both as a standalone application and SketchUp plug-in, OpenStudio is an open-source software that provides a visual, user-friendly interface for the EnergyPlus analysis engine—a console-based program that reads and writes only text files. The SketchUp plug-in generates building geometry formatted specifically for input into EnergyPlus. After the geometry is created, users can define material properties, systems, and zones in the OpenStudio application. Once the model is fully attributed, they can then run multiple simulations with the Parametric Analysis Tool (PAT), test different configurations with a drag-and-drop editor, and obtain life-cycle cost information.

Because OpenStudio is open source, it does lack the support and documentation provided with commercial software. It also doesn’t work well with existing SketchUp models. Rather, for best results, design teams must model the building envelope in SketchUp using specific OpenStudio rules and requirements. That said, the resulting data from the analysis is extensive and the PAT provides a quick and easy way to compare options.

OpenStudio interface
Michael Kilkelly OpenStudio interface
OpenStudio can run multiple simulations with the Parametric Analysis Tool
Michael Kilkelly OpenStudio can run multiple simulations with the Parametric Analysis Tool

IES Virtual Environment for Architects, by Integrated Environmental Solutions

Works with: Autodesk Revit, Trimble SketchUp, Vectorworks, and any modeling software that exports to gbXML
Cost: Contact IES for more information
Integrated Environmental Solutions (IES) offers a range of energy modeling tools based on the Apache simulation engine. IES Virtual Environment (IESVE) for Architects is an architect-friendly version of the developer’s base IESVE product, which is targeted to engineers and energy-modeling professionals. Using a plug-in for Revit, SketchUp, or Vectorworks, architects can export their models to the IESVE application for analysis and then simulate water usage, daylighting, solar shading, energy use, and heating and cooling demand. A simulation report conveys results through charts and diagrams.

This program performs a very thorough building analysis, but it is not as user-friendly as some of the other options listed here, nor does it provide the real-time feedback that is helpful during early design stages. Also, since IES is based in Scotland, the software references European energy standards though it will calculate potential LEED credits.

Michael Kilkelly

The Outsourcing Option

BIM IQ Energy is a building-performance simulation service provided by Oldcastle BuildingEnvelope using material data generated from Oldcastle’s BIM IQ Render plug-in for Revit. The service uses a proprietary energy-simulation engine to calculate building performance quickly and provide immediate feedback to designers. Because simulation specialists handle the number crunching, architects do not need to master yet another software program to estimate their project’s energy performance. Contact Oldcastle for pricing.