There is an immediate need in the marketplace to be able to identify residential retrofit software modeling tools that have both tested physics engines, and interfaces that allow them to consistently and accurately model a wide range of energy retrofits. The use cases for these retrofit software tools do not require the delivery of an energy rating.
The RESNET Board of Directors voted to create a RESNET Working Group on Retrofit Audit Standard that is chaired by Greg Thomas of Performance Systems Development. The working group’s membership is composed of representatives of two national laboratories and the leading modeling software developers.
The charter of the working group is to: “draft a standard based on the BENTEST Tier 1 and/or Tier 2 Tests, the RESNET HVAC tests, the RESNET Distribution System Efficiency test (DSE) and the RESNET DHW test and consideration of a minimum set of improvement calculations.”
RESNET intends to provide clear guidance to the market on how to develop software that can consistently pass a strong retrofit calculation test. Software tools developed using strong physics engines should be able to reliably pass such a test. Software tools using measure specific engineering calculations will be difficult to test using a performance based test that focuses on testing an underlying simulation engine. Without using a “whole model” approach, each individual improvement calculation should require testing, a process that would be very difficult to administratively support. Developing a test for each calculation is possible, but will take time and funding to develop.
RESNET has all the testing requirements in place to be able to approve simulation based residential retrofit software modeling tools. The HERS BESTEST Tier 1 and/or Tier 2 Tests, the RESNET HVAC tests, the RESNET Distribution System Efficiency test (DSE) and the RESNET DHW test, when combined do an excellent job of testing the strength of a software model. When a wide range of improvements are put into strong physics energy models that have passed these tests we can have increased confidence that the physics engine is delivering a result based on science and not a unique and unknown calculation customized for a specific improvement.
The BESTEST EX effort or another test based on real consumption data could eventually be a complimentary addition to the testing of software physics if a version becomes available that has a viable administrative process.
One additional requirement would be to develop a list of energy conservation measures that the software tool must be able to model. This is the retrofit version of the minimum rated features of rating software. Such a list already exists in the form of the Home Star incentive categories.
The existence of these tests and supporting documents would allow RESNET to quickly put in place a test for existing residential retrofit software that could be confidently be referenced by state and local programs nationally. The retrofit software testing standard process could be refined and enhanced over time.
RESNET will engage the Building Performance Institute, Efficiency First and the U.S. Department of Energy in this effort.
Once these retrofit software modeling tools are developed to this subset of the current standard, it will also likely act as a stepping stone to making more energy rating tools available, enhancing market competition.
Persons that are serving on the working group are:
Greg Thomas, Performance Systems Development (Chair)
Philip Fairey, Florida Solar Energy Center
Dean Gamble, ICF International
Matt Golden, Recurve
Joel Gilbert, Apogee Interactive
John Jones, Building Performance Institute
Mick Rickwood, Conservation Services Group
Dave Roberts, National Renewable Energy Laboratory
Rob Salcido, Architectural Energy Corporation
Iain Walker, Lawrence Berkeley National Laboratory
This post was submitted by Steve Baden.
