Frequently asked questions BACK

  1. How do I make sure that I am using the latest version of the software?
      Please periodically download a fresh copy of the program and re-install it. Do not delete anything, just let the new files overwrite the older ones by selecting "no to all" when asked by the setup wizard.

  2. Can Sapper version 12 be used to read a Sapper version 9 file?
      Yes, but you will probably need to re-enter the data in each section to be on the safe side. The two programmes are quite different from each other.

  3. With Sapper software when I try to save the calculation I get an error message and the program crashes. Why?
      With older versions, if your file name includes "/" , "\" , "|" or ":" it will crash so choose another file name. Later versions have dealt with this so please download a new version.

  4. What's new with Sapper version 12?
      There have been many changes in SAP 2012, some of which are to make the calculation more accurate, and some to make the system more flexible, enabling a variety of new and existing technologies to be included:
    • Monthly calculations. Space and water heating is now calculated monthly.
    • FEE and TFEE calculations. Required for Building Regulations compliance.
    • Party walls. It has been found by Leeds Metropolitan University that air movement in some party walls leads to previously unexpected heat losses. It is therefore necessary to seal any cavities in order to minimise heat losses. U-values for cavity walls are now included in the calculation.
    • Thermal bridging. Detailed thermal bridging needed rather than assumed default values. The software include the possible use of default value of 0.15, calculated individual values, values from SAP tables, or calculated global value. In Scotland values for accredited details can be entered.
    • Thermal mass. Thermal mass is a measure of how “lightweight” or “heavyweight” a building is. Heavyweight energy-efficient homes generally make better use of solar gains in the day by absorbing them and radiating the warmth later on as the level of solar radiation drops. The thermal mass is taken into account in the summer overheating calculation.
    • Cooling. There is now a facility for including air-conditioning systems (selected from the Product Characteristic Data File), but the use of cooling will increase the DER.
    • Hot Water. In England and Wales, if the dwelling is designed to use less than 125 litres per person per day, the assumed water usage is reduced by 5%. This does not apply in Scotland.
    • Multiple heating systems. The software now allows for a dwelling having two main heating systems
    • Heat pumps. Heat pump systems can now be selected from the Product Characteristic Data File (PCDF). This will probably allow better Coefficient Of Performance(COP)
    • New Technologies. Multiple New Technologies (Appendix Q) can now be selected.
    • Internal gains. The DER will assume a level of gains that is around 33% lower than that assumed in the SAP rating. This is to encourage builders to get the heat and cooling demand of the dwelling down to a level that presumes the presence of low-energy appliances and lighting.
    • Waste water heat recovery. This system can be used in certain situations to recycle heat from shower waste water. Sapper version 9 makes it easy to select a system from the PCDF.
    • Flue gas heat recovery. Recycles heat from boiler flue gasses to make a small reduction in the water heating requirement. Sapper version 9 makes it easy to select a system from the PCDF.

  5. As a user of Sapper, will I have to pay full price for the new software.
      No, as with previous updates, there will be a special discount for existing users wishing to update.

  6. Does the new U-value calculator do calculations for warm roofs?
      Yes. You simply specify the layers as usual choosing a layer called 'unventilated loft space (warm roof)'. You will be asked for the total areas of components between the inside and the loft space, and the area of components between the loft space and the external environment. The calculation required by BS EN ISO 13789 is quite complicated but with Dewpoint it all happens automatically. The program will display and print the full calculation. You can also save the calculations for use in other projects.

  7. Is there a program which checks compliance with the new AD Part L2 Buildings Other Than Dwelling?
      It is now neccessary to use sBEM software available from BRE.

  8. I do not want to buy the U-value calculator but I need a U-value calculation done. Can you do that for me?
      Yes. Click here to request a U-value calculation (cost £20.00).

  9. My project has a DER lower than the TER but seems to fail, why would that be?"
      While running the program, go to Display > Compliance checklist summary. Check through this summary and you will probably find the reason. One common reason is to do with heating controls. If the dwelling total floor area is greater than 150 sq.m. it is necessary to specify 'time and temperature zone control' . The DER must comply but some of the other possible failures can be discussed with Building Control

  10. I do not want to buy the SAP calculator but I need a SAP calculation done. Can you do that for me?
      Yes. Click here to request a SAP calculation (usual cost £150.00).

  11. Is there a way to send the completed reports electronically?
      Yes. I use CutePdf pdf writer which acts like a virtual printer, making your printed outputs into pdf.files which can be read with Adobe Acrobat reader. CutePdf is freeware and can easilly be downloaded from
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