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RESNET® Selects Energy Modeling Director: A Big Step to Enhance the Consistency of the Calculation of HERS® Index Scores

Oct 11, 2018

A key to ensuring the quality of HERS® ratings is to enhance the consistency which the various accredited HERS® software programs calculate HERS® Index scores. Too often in the past, the same home could receive a different score based upon the software program being used.

For the past four years, the RESNET Board has been striving to enhance the consistency of the calculation of HERS® Index Scores.

A key element to meet this policy is the establishment of a RESNET Board Software Consistency Committee (SCC) and securing the services of a RESNET Energy Modeling Director.

The RESNET Energy Modeling Director will act as the arbitrator of the SCC, making technical decisions about modeling tests, requirements, and guidelines with the support of other members of the committee. The position will also be the liaison between the SCC and RESNET staff.

Other responsibilities include:

  • Respond to software modeling consistency inquiries from RESNET membership:
    • Investigate instances of software modeling tools calculating different results with similar inputs.
    • Research and identify what major drivers are causing the inconsistency by using the relevant software tools and leveraging the Software Consistency Committee.
    • Propose resolutions that will enhance consistency between software tools.
  • Generate and update modeling guidelines to improve consistency of modeling techniques between software tools.
  • Propose RESNET Standards updates to enhance software consistency.
  • Enhance and expand RESNET test suites to enforce software consistency.

After a RFP process, RESNET has selected Big Ladder Software to serve as out Energy Modeling Director.

Big Ladder Software is a Denver-based company dedicated to providing software and services for the building energy modeling industry. The company name reflects its mission to “help our clients reach new heights”. Big Ladder president, Peter Ellis, founded the company in 2009 after a six-year career at the National Renewable Energy Laboratory (NREL) in Golden, CO. Today, Big Ladder is a team of programmers, engineers, and scientists with a unique combination of expertise in software development, computer simulation, and building science. Over the past nine years, the company has experienced steady growth and achieved significant success and recognition in the industry.

Big Ladder provides software, training, support, and consulting services for a number of architectural engineering and design firms in their local area of Colorado, as well as nationally. The U.S. Army Corps of Engineers uses Big Ladder’s software to help Army installations achieve aggressive energy saving goals. The company also does contract work for the U.S. Department of Energy through the National Renewable Energy Laboratory (NREL). Their client roster includes many other high profile organizations including ASHRAE, California Energy Commission (CEC), Electric Power Research Institute (EPRI), Southern California Edison, Xcel Energy, Rocky Mountain Institute (RMI), Southwest Research Institute (SwRI), Navigant, McKinstry, Iconergy, and MKK.

The team that will be working with RESNET are:

Lead Member

Neal Kruis, PhD

 Dr. Kruis is Vice President of Big Ladder Software. He has a doctoral degree in building systems engineering from the University of Colorado at Boulder. His current responsibilities focus on the development of computational software for building energy analysis. He is a core member of both the EnergyPlus and California Simulation Engine (CSE) development teams1 as well as California’s Title 24 compliance software CBECC-Com and CBECC-Res development teams.  Prior to joining Big Ladder, Neal worked at the National Renewable Energy Laboratory (NREL) where he developed the Building Energy Optimization (BEopt) tool within the residential buildings research group. Neal has published peer-reviewed articles on the topics of simulating foundations, fenestration, hot water, and direct expansion vapor compression systems. He is an active member of ASHRAE where he is involved in several technical and standards committees.  Neal is also on the board of directors for the U.S. chapter of the International Building Performance Simulation Association (IBPSA-USA).




Other Team Members

Bruce Wilcox, PE

Bruce Wilcox leads projects for government and industrial clients involving standards development, field experiments in building science and the development and validation of energy calculations and software. Bruce is the current prime contractor and project manager for the Residential Building Science Technical Support project where a large team is developing state of the art simulation, rules processing and user interface software for code compliance and providing services related to Low-Rise Residential Energy Efficiency Standards for the California Energy Commission (CEC). Bruce was also the prime contractor for the 2013, 2016, and 2019 Title 24 code cycles. Bruce is the prime contractor and project manager for the Central Valley Research Homes program which uses four unoccupied, highly-instrumented laboratory homes in Stockton to validate and improve CEC energy simulation algorithms and demonstrate cost effective ZNE retrofits. Bruce developed the first tests for California residential compliance software for the California Energy Commission.

Matthew Larson, PE, CEM, BEMP, LEED AP BD+C

Matthew Larson holds a bachelor’s degree in engineering science from Colorado State University in Fort Collins, CO and is a licensed Professional Engineer in the State of Colorado. He has also achieved certifications as a Building Energy Modeling Professional (BEMP) through ASHRAE, Certified Energy Manager (CEM) through Association of Energy Engineers (AEE), and LEED Associated Professional (AP) for Building Design and Construction (BD+C) through US Green Building Council (USGBC). Matthew has been using EnergyPlus for more than eight years over a wide range of projects and building types. He has extensive knowledge of modeling with ASHRAE Standards 90.1, 62.1, and 55 to achieve project goals. He has been providing training and support for EnergyPlus and other software tools for the past three years. Matthew has experience using CBECC-Res and CSE, and performed comparisons against EnergyPlus for residential building models. He has also been project manager and lead energy modeler for multiple projects for research institutes and utility companies involving portfolio parametric analysis across multiple climate zones, building types (commercial and residential), vintages, and HVAC systems.

The securing of the RESNET Energy Modeling Director is a big step in bringing greater consistency to RESNET HERS® Software tools.