PHPP and Terraced Houses

[Rachel Mitchell]

I am currently modelling 4 terraced house and am assuming that I treat this as one building in terms of a PHPP calculation and not four separate calculations. As they all will have the same heating/hot water/MVHR layouts I am assuming that this is the right approach.
When I am inputting hot water runs etc am I right to assume that I just put in 4 x the lengths etc
Thanks

[Toby Cambray]

Yes, correct - consider it as one building with four dwellings within it. There's a box on the verification page indicating number of dwelling units that will need to be 4.

[Nick Grant]

Hi Rachel

One thing to watch is the vent sheet if each has it's own MVHR.

If they are all the same it's easy. Enter the vent rate, duct length etc for one dwelling in othe vent sheet and note the calculated efficiency including duct losses.

Enter this in the user's own MVHR data box and call it mvhr with losses say.

Now put in the ventilation rate for the whole terrace and select 'mvhr with losses' as the unit. Delete the ducts and that should be it.

Nick

[Rachel Mitchell]

thanks Nick and Toby,
Nick my next question on how to deal with the MVHR so thanks for answering that one in advance!

[Rachel Mitchell]

I also have another MVHR question, I have a large house -600m2 and it will possibly need two domestic MVHR systems to provide the correct amount of supply/extract air
supply is 403 and extract 540, is this the correct approach or should I be looking at a commercial MVHR unit?

[Nick Grant]

1. Supply should equal extract.

Probably tricky as I assume occupancy varies a lot. A danger in over ventilating in winter when occupancy low, leads to dry air.

ncant help beyond that but a competent equipment supplier should be able to advise.