Diagnosing Different Results Between Ekotrope and REM/Rate

If you are getting a significantly different result (HERS, code compliance, etc.) in Ekotrope and REM/Rate, we recommend the strategy described below to try to identify the cause(s) of the difference.  Please keep in mind that small variations between software tools are normal.  All the RESNET accredited rating tools have different underlying engines and will produce different results.  Variations of ~2 HERS points are common.  Larger discrepancies should be investigated.

Compare End Use Consumption

Using the Fuel Summary Comparison reports available in both Ekotrope and REM, you can determine which end use(s) (heating, cooling, hot water, lighting & appliances and/or onsite generation) is causing the discrepancy.  For a HERS discrepancy look at the HERS Rated and Reference Fuel Summary Comparison in Ekotrope and the Fuel Summary in REM with HERS Reports selected in the Building Selection.   The Code Compliance Performance Reports can also be used for this purpose.

If you identify that hot water, lighting & appliances or onsite generation is a big source of discrepancy then look at the corresponding inputs.  For heating and cooling, you can check to make sure the heating and cooling equipment are modeled the same in Ekotrope and REM and if they are, move on to comparing the Component Loads.

Compare Component Loads

You can compare component loads by following the instructions in this article.

Comparing Reference and Rated/Proposed Houses

Sometimes the cause of a difference between Ekotrope and REM lies in the creation of the Reference and Rated Homes.  These can be checked by looking at Ekotrope's Building Summary Reports and REM's Building File Reports.  For HERS, you would look at the HERS Rated and Reference Home Summary reports in Ekotrope and the Building File Report in REM with the HERS Reports Building Selection.

Contact Support

If you don't find an input problem and the result change is significant or will affect your business, then please contact support and we will do our best to assist you!