Validation of the International Code Compliant Calculator (IC3) v3.10 Using the RESNET Verification Procedures

Abstract

This report presents results from the testing and validation of the Energy Systems Laboratory’s web-based software tool - International Code Compliance Calculator (IC3), v3.10, using the Residential Energy Services Network (RESNET) verification procedures - RESNET Publication No. 07-003. It is the continuation of the previous 2009 RESNET validation report of IC3 v3.3. The IC3 software is a web-based tool to demonstrate compliance of single and multifamily residences with the Texas Building Energy Performance Standards (TBEPS) (i.e., the 2000 International Energy Conservation Code (IECC) with the 2001 Supplement, the 2006 National Appliance Energy Conservation Act (NAECA) revisions, and the 2009 IECC). The user-interface of IC3 was designed to ensure simple and quick input through reduced user input fields and present a simplified output by only reporting the codecompliance as percent above or below code for locations in Texas. The RESNET verification procedure is a set of verification tests that are required for RESNET accreditation of IECC performance compliance software tools. It was developed to ensure the accuracy and comparability of software to be used for verification of tax credits, home energy ratings, and compliance with the IECC. The verification procedure applies to the 2004 supplement of the IECC and to the 2006 IECC. The home configurations and operating conditions for the Standard Reference Home and Rated Home are required to be adopted from RESNET (2007) or Section 404 of the IECC, supplemented by the 2006 Mortgage Industry National Home Energy Rating System Standards. To test the IC3 using the RESNET verification test suite, a special version of the Desktop DOE-2 Processor (DDP) spreadsheet was developed since the test runs for RESNET accreditation cannot be performed using the user interface of web-based IC3. The DDP spreadsheet is the ESL’s internal desktop version that utilizes the same DOE- 2 simulation procedures as the web-based IC3. The DDP spreadsheet has the flexibility to calculate compliance with other codes by auto-generating the corresponding standard reference designs, incorporates additional weather locations, and reports the simulation results in a pre-specified manner as well as modification of selected simulation inputs, which are not available in the user interface of IC3. The DDP spreadsheet can be uploaded to the ESL’s web server for processing, and the results can be downloaded after the processing to view the simulation results. The RESNET verification procedure consists of the five test suites: 1) Tier one of the HERS BESTEST; 2) IECC Code Reference Home auto-generation tests; 3) HVAC tests; 4) Duct distribution system efficiency tests; and 5) Hot water system performance tests. The specifications and acceptance criteria of each test suite and the test results of IC3 are presented in Section 2.1 to 2.5. The results show that IC3 is a code-compliant simulation program that conforms to the acceptance criteria for each test suite.