Failed SAP

[Huckleberrys]

With a combi boiler it wouldn't be that easy a swap to an ASHP. I'd stick with mains gas also is the house is as low a rating as you say. Heat pump may not get it warm enough!

[TonyT]

Did you remember to tell them it was low e glass in the double glazed units and you have weather compensation programmer on your boiler?

[Alan Ambrose]

If there an inline SAP calculator somewhere so that you can put in your current build set-up and verify the SAP numbers and then look at alternatives to see how they vary the score?

[AliG]

Make sure they have the right U-values for your windows, I think many double glazed windows have much better U-values than the assumed value they use if they do not have the actual value which is only 1.8.

 

Same for the other aspects of your insulation. I know they have tightened up the minimums but I think you have achieved them with the described insulation levels. The wall have quite a poor level of insulation in them and as they are already close to the minimum again it is important to know exactly what kind of insulation is in them as it will impact the calculation.

 

 

[saveasteading]

2 hours ago, AliG said:

Make sure they have the right U-values for your windows, I

The cheaper the quote for this assessment the more they will enter generic figures and the tick boxes that are easiest.

Otherwise there would be dozens of questions for you to answer, and you'd be passing them on to your suppliers, who don't necessarily know the answer.

 

I'm used to SBEM not SAP but it seems similar. The difference between the first assessment and the answer we needed was once a single tick in the right box for the gas boiler efficiency. I dont think the assessor eve realised the significance (basically a percentage was applied in the formula, making more difference than it should have).

 

would your assessor send you a draft of the assessment?