Why does the building fail on Criterion 2, Walls or Floors, when all the external constructions are correctly insulated?

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The failure is probably caused by a heated zone being adjacent to an unheated zone and the partition (wall or internal floor/ceiling) construction between them is uninsulated. To fix the problem either insulate the partition between the heated and unheated zones or heat the currently unheated zones. 

The failure is probably caused by a heated zone being adjacent to an unheated zone and the partition (wall or internal floor/ceiling) construction between them is uninsulated. To fix the problem either insulate the partition between the heated and unheated zones or heat the currently unheated zones.

How to fix?

You should first check if some of the unheated zones can be considered 'Indirectly Conditioned (EPC Conventions $6.13) and make changes where relevant. This may take some of the partitions / internal floors out of the analysis.

The U-value table will report the  Area weighted average U-Value (Ua-Calc) using external walls and internal partitions with this adjacency. SBEM will identify the wall construction used in this calculation which has the highest U-Value (Ui-Calc) and report its U-Value along with one place where it is assigned (zone: 1st Floor - Heated in this case). This will then help to identify the precise location/construction which needs insulating: 

It is likely that there will be other places where a similar partition is causing problems achieving compliance such that once one partition is insulated, other locations will also be reported. 

Differences between DSM and SBEM reporting

SBEM has just 3 different categories of construction (excluding Doors and Windows): 

    • Roof

    • Wall

    • Floor or Ceiling

Thus it cannot differentiate between an internal floor and internal ceiling and treats a ceiling with an unheated space above, as a floor construction (as it does a floor with an unheated space below). Thus both of these are reported in the floor analysis:

In this case the 'floor' is the ceiling between zone 'Ground Flr - Heated' and zone '1st Floor - Unheated'. 

In DSM  the same thermal envelope will be reported under the Roof category:

Where the unheated space is below rather than above, it will be included in the Floor assessment (as SBEM):

Also note that in generating the BRUKL Report, U-Values are rounded to 2 decimal places before checking and reporting the values. A Wall U-value of 0.264, Ground Floor U-value of 0.184 and Roof U-value of 0.184 were used in the analysis below:

The following diagrams show an elevation cross-section with conditioned and unconditioned spaces. 

The diagrams show constructions INCLUDED and NOT INCLUDED in the U-Value analysis:

1. SBEM

2.DSM