PLQ 3.4 – Frank SAPpa

Hello BIMfans,
Now that I’ve produced Tŷ Crempog‘s information model, it’s time (finally) to put it to practical use in answering my next and final Plain Langauge Question:

What are the most cost-effective thermal improvements that could be undertaken?

By answering this Plain Langauge Question, I am beginning to realize the true potential of Tŷ Crempog‘s information model by answering real questions that will impact on how I undertake any retrofit works.  To answer this question, I have turned to Standard Assessment Procedure (SAP).


SAP is Building Research Establishment (BRE)‘s procedure to calculate the energy rating of dwellings.  SAP has been referenced in Approved Document L of the Welsh and English building regulations, been adopted by the UK Government and is used to assess dwellings to produce their Energy Performance Certificate (EPC).  New dwellings use SAP in its entirety while, as of November 2017, existing dwellings like Tŷ Crempog (or Joe’s Garage) use the Reduced Data Standard Assessment Procedure (RdSAP) to support completing the SAP calculations.

The advantage of RdSAP is that it provides several permitted assumptions that can be used within the SAP calculations.  I plan on using Tŷ Crempog‘s information model to complete the (385!!) values required.  Now there are too many values to do at once, so instead of having a Freak out! I am addressing each section at a time; using RdSAP to fill in the gaps.

Once my SAP calculations are complete, I will be able to manipulate the information to see what improvements will provide the greatest impact.  For example, would it be more cost effective to improve Tŷ Crempog‘s thermal performance, reduce the infiltration rate or improve the efficiency of my heating system?  Once complete, I will be able to test these scenario’s and inform future home improvements.

BIM, placing asset information into the palm of my hand


1 Overall Dimension

Section 1 of the SAP Documentation is related to a dwelling’s overall dimensions to determine its internal volume.  SAP asks for each floor’s area as well as their average ceiling height.  The total floor area (4) is used to calculate thermal mass, heat loss, internal temperatures, space heating, space cooling while the dwelling’s volume (5) is used to calculate infiltration and heat loss.  Note:  RdSAP says that internal measurements are permissible and that I can ignore the floor area of my attic as it doesn’t have a fixed staircase.

Luckily for me, the area of each room as well as their usable heights are already within COBie; providing me with all the information I need to complete section 1.

Now that I’ve identified the structured information I need, it needs to be exchanged into a Google Sheet.  Thanks to Google, The mothers of invention, Google Sheets is able to reference information from other sheets.  Which means using formulas like:

=SUM(importrange(“URL”, “Sheet!Range”))

allows me to automatically import my Architectural COBie.  This means that I am using Tŷ Crempog‘s information model to calculate the area of my floors as well as their average height to calculate my total floor area (4) and dwelling volume (5)Note:  Because COBie specifies a specific sheet and column orders, my formula will always point to the Space.Area column, even if I publish a revised COBie.

My calculations for SAP – Section 1 can be seen below:

And there we have it.  While I have only just started, it seems possible to automate the population of SAP using Tŷ Crempog‘s information model, having done so using COBie.  This fills me with a lot of confidence that I can use my information model to complete the other SAP sections.  Fantastic, PLQ 3.4 is underway!

Operation and Maintenance

  • 3.1 What are the sizes and condition of the windows & doors?
  • 3.2 What assets are in a poor condition?
  • 3.3 What costs can be attributed to my assets?
  • 3.4 What are the most cost effective thermal improvements that could be undertaken?

Now that my overall dimensions have been calculated, it is time to look at Ty Crempog‘s ventilation rate and heat loss…

Note:  If you have any comments regarding my use of SAP, then please let me know either on Twitter, or by commenting below.

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