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Submit plansWe are almost at the end of our two-year self-build project in Kent. We have built a block and brick house which is sunken into the ground. We were keen to make sure our home energy efficient and sustainable, and have spent a lot of money doing so.
After lots of research we opted to buy a MVHR system and install it ourselves to save money. However, now our energy calculation company doing our SAP and Part O has said that the one we installed is not tested to BS EN 13141 and it will fail Part L.
I have spoken to the supplier, and they don't seem concerned that the unit isn't tested and won’t consider a refund as it’s been used.
Is the energy calculation company right that the unit must be tested to BS EN 13141? And what happens if we fail Part L? Is my supplier breaking any laws selling something that hasn’t been tested?
Many MVHR units are tested to BS EN 13141 ‒ 7 but it is not imperative, and other standards can also be used. The system must be commissioned and certificated in accordance with Building Regulations Part F system 4 by a qualified engineer with an in-date calibrated vane anemometer, and the certificate then given to Building control. Part F is the building regulation covering ventilation but Part L ‒ which is the one quoted in the letter from your reader ‒ is about energy efficiency. Therefore, this regulation looks at the efficiency and energy use of the fan unit, and if it is indeed tested in accordance with a recognised standard, then the calculation is easier.
It is not clear which particular fan unit has been used, so I cannot check the technical data. If the fan unit is listed on the Product Characteristic Data Base (PCDB) ‒ formerly known as SAP appendix Q ‒ then the data can be used in SAP. I would be pushing the suppliers and manufacturers for the required data, or they may need to change the fan unit for one that is recognised in SAP, even if that does unfortunately cost a bit more.
David Hilton, Build It’s renewables and ventilation expert