PLQ 3.4 – EPConclusion

Hello BIMfans,
After previously considering my Overall Dimensions, Heating Requirements and Internal Gains, I am now able to complete my Standard Assessment Procedure (SAP) calculations by looking at my final three categories:  9a_Energy Requirements, 10_Fuel Costs, and 11_SAP Rating.

Go on Crempog, climb those ratings!

Energy Requirements

  1. Space Heating (211).  To calculate the amount of energy needed to heat Tŷ Crempog, SAP requires the previously calculated monthly space heating requirements (98) as well as my boiler’s efficiency (206).  Using the SAP Product Database, I was able to find an efficiency rate of 76.1%.  As expected, my boiler’s efficiency has a significant effect on the energy needed for space heating (211).

    The SAP product database can be accessed from here.
  2. Total Electricity (services) (231).   In a similar vein, as my boiler was installed before 2013 I’ve had to use 120 kWh/year instead of an assumed 30 kWh/year.  This means that, in addition to any efficiency gains, I could quarter the energy use associated with my boiler by having a new one installed.
  3. Total delivered energy for all uses (238).  Each of the calculated energy uses were collated to calculate my total delivered energy.  Interestingly, SAP includes an opportunity to subtract renewable energy sources; making the addition of solar panel an option to consider.  However, as my roof faces east and west, this option might not be as attractive as it seems. 

My SAP calculations for energy requirements can be seen below:

Fuel Costs

  1. Total Energy Cost (255).  As I am not able to choose my fuel, there isn’t much I can do to influence this cost aside from reducing my energy requirements.

My SAP calculations for my fuel costs can be seen below:


SAP Rating

  1. SAP Rating (358).  After all of these calculations, I’ve come to a final value. Using the total energy cost (255) of Tŷ Crempog and total floor area (4), I am able to calculate the energy cost factor (357); allowing me to calculate my SAP rating (358).Months of calculations and tests have allowed me to arrive at a single number, 66.50.  My ‘official’ SAP rating you ask? 65 (Pretty damn close if you ask me!).

My SAP calculations for SAP Rating can be seen below:

To double-check these figures (and increase my level of confidence), I contacted BRE’s Energy Team, who were kind enough to review my calculations.  After a few exchanges, I believe we have managed to spot and correct most, if not all, of the errors to arrive at a pretty realistic SAP score.  This means that I am able to test scenarios and see the impact any improvements have on Tŷ Crempog.

Now that my calculations are complete, I am happy to share them:

Having these calculations in Google Sheets is great because I am able to share and test these results.

It is so easy, I am issuing a challenge:

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

Using the structured information provided in my Calculation Sheet and SAP Documentation, what improvements can you test and suggest back?  The best suggestions will feature in next month’s blog post!!!  For example:

  • Backdoor:  A new backdoor would improve (26a) from 3.00 to 1.4; increasing my SAP rating by (an unimpressive) 0.3.
  • Boiler:  A new boiler would improve (206) and (230c); increasing my SAP rating by up to six whole 6 points!

So, let your creativity flow, and see what solutions you can think of:

Answers in the comments section below or via social media, please!

And there we have it.  Having now completed my SAP Calculations using Tŷ Crempog‘s information model, I should now (with your help) be able to determine the most cost-effective thermal improvements that could be undertaken.  In doing so, PLQ 3.4 will be complete!

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 SAP rating has been calculated, Let’s see what potential improvement works you lot have suggested…

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

5 thoughts on “PLQ 3.4 – EPConclusion

  1. Hello Dan, I’ve noticed you use six numeric digits rather than four for your file name, are you following BS1192-2 or PAS 1192-2?


    • Hi J, I use five digits.

      BS 1192 specifically states four, while PAS 1192-2 shows five. I have used five on purpose so that I could codify by number field. I have explained this in clause 5.3 of my BIM Execution Plan.


  2. My first suggestion is dry-lining the walls with Alreflex 1L1 and finishing with plasterboard on battens; assuming the existing U-value of your walls is 2.1 W/m2K, adding our insulation will reduce the U-value of the walls to 0.82 W/m2K AND reduce the heat capacity per unit area of the wall to 9 kJ/m2K.

    This still won’t quite comply with the requirements of Approved Document L1B, so you may need to consider insulating with 85 mm Alreflex Platinum instead to reduce the U-value to 0.28 W/m2K if the building control officer thinks that that the extra thickness required is technically feasible.

    The two changes required in your spreadsheet on the 3_HeatLoss tab are:

    E10 = 0.82 or 0.28 (as preferred)
    G10 = 9

    More information on Alreflex 1L1 and Alreflex Platinum can be found on the Thermal Economics website:; or I will be happy to discuss this with you.

    We’re happy to give technical advice on how our thermal insulation products affect the energy performance of buildings; including calculations for U-values and thermal bridging. Just call our technical department on 01582 544255 or e-mail


    • Thank you John, I have been thinking about EWI systems, but yes a VIP-esq dry lining solution could also work well. Alreflex 1L1 has a massive impact at a thickness of only 3mm


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