more UFH questions, calcs?

[ADLIan]

Use of oil does not help due to CO₂ emissions. Also, unless instructed to do so, the assessor has been very lazy in adopting the default values for linear thermal bridging (2a) and no air leakage test (3). The detailed analysis of the linear thermal bridging is time consuming (=costly) but something I always do as the default y-value of 15 is a real pain to overcome. Similarly not doing the air pressure test is false economy. There are a couple of other items open to question but without more detail I cannot comment.

 

[PeterW]

@albert what is being done to address this lot as your issue doesn’t seem to be ASHP vs Oil, it is actually meeting the base regulations. 

[Conor]

Change your 150mm floor slab to 100mm and stick in another 50mm insulation. Nominal cost difference but you'll save a load on reduced heat loss. We're on a tight budget for a similar sized house, focusing spending on insulation and thermal envelope. I'm happy enough to have a basic IKEA kitchen in exchange for minimal heating needs.

[SteamyTea]

1 hour ago, PeterW said:

Kw

Add kW and kWh to your autocorrect.

[albert]

 This is a barn conversion, BC have passed it, but  I have upgraded Windows and doors at 1.3 now and floor upgraded also to 100mm PIR.. I will check with assessors again that all is OK.

 

Thanks again for advice.  

[ADLIan]

Barn conversion is a world of difference compared to new build, should have mentioned this at the start. DER/TER and DFEE/TFEE do not apply and defaults for linear thermal bridge and air pressure test are correct. This report is not required for barn conversion (hence confusion in this thread) as required elemental u-values etc are listed in Appr Doc L1B, not L1A. Only use of SAP in this instance is to generate the EPC on completion.

[albert]

 Yes sorry I posted the sap report  for the heat loss info. But fully  take on board the need for more insulation to the GF to  minimise heat loss from UFH.  Being a Class Q steel frame the structure in complicated. I have time to boost the PIR under the slab.

 

Getting back to the ASHP size,  does 19kw  sounds excessive ?? based on those heat loss figs as worst case.

 

 

[PeterW]

19Kw still sounds excessive as your daily losses in the worst month would easily be covered by something half the size.