As Built Shell and Core fails BRUKL when As Designed passes

Modified on Fri, 25 Apr at 12:43 PM

1. DSM software: Notional Building PV

There is a bug in v7 DSM in regard to the (As Built Shell and Core) calculation of the electricity generated in the Notional Building from Photovoltaics.

To fix this issue you will need to modify the As Built Foundation Area using the following Formula:

Modified Foundation Area = Actual Foundation Area * (As Built Floor Area / As Designed Floor Area)²

Example

This building is two storeys, conditioned throughout and has a total floor area of 600m² .

The foundation area is 300m²

360m²of the floor area is Fit-Out.

The As Designed Summary Report appears thus:

The analysis is switched to 'As Built' which generates these results:

The As Built calculation shows a Fail on both Emissions and Primary Energy. Now this may happen for the As Built calculation because the specification of those (Core) areas may not be to the same efficient specification as the Fit-Out areas. However, unless all heating generators are heat pumps the Notional Building will have a PV System and that PV System will most likely be larger than that for the As Designed calculation.

In this example the As Built calculation has a Notional Building PV system generating 14.76 kWh/m² (based on an area of 240m²) when the As Designed calculation has a PV generating 2.73 kWh/m². This has happened because the algorithm has multiplied the Foundation Area by (As Designed Area / As Built Area) rather than (As Built Area / As Designed Area) in order to generate the size of the PV.

To cancel out this error it is necessary to reduce the Foundation Area so that when it uses the (As Designed Area / As Built Area) the error in this calculation is cancelled out.

Modified Foundation Area = Actual Foundation Area * (As Built Floor Area / As Designed Floor Area)²

^{Noting that As Built Floor Area / As Designed Floor Area in this example = 240 / 600 = 0.4}

^{Modified Foundation Area = 300 * 0.4² = 48m²}

^{Editing the Foundation Area for the As Built calculation, the results become:}

^{Note that only the Notional Building PV System is changed by this (the summary reports show all the services in Actual and Notional Building are the same). However the BRUKL will report an incorrect Foundation Area which may need explaining to Building Control.}