Party Walls in PHPP

[Mike Jacob]

If I have a 25mm gap between two houses and then fill it with EPS beads can I classify that wall as a party wall in PHPP?

[Nick Grant]

And I responded on Linked in! Trouble is most people here will then miss the discussion (chance to learn or correct) and there is no nice reference left for others.

[Anonymous]

And for the rest of us, the answer is?

[Mike Jacob]

1 answer was yes should be ok. Other answer was no. Hopefuly Nick and Alan can discuss on here.

[Alan Clarke]

Mike
As a rule be good to use twitter to flag up a question posted and discussed in more detail on the forum – taken me a day to work out what your last 140 chars were on about.
Alan

[Alan Clarke]

Whether there is a continuous heat loss to the neighbour depends on how well they are insulated. Same level of insulation; then assume no heat loss. But if you're building a passivhaus onto an uninsulated building then even if it is occupied the average temperature will tend to be lower than in the passivhaus. (This is because intermittent heating will be used and the building will cool down during the night and during the day if unoccupied, even if the thermostat is set the same. Also rooms outside the living area will tend to be cooler the higher the heat loss of the building).

So to deal with this you do need to use the temperature zone X line in PHPP. To do this we used the SAP formulae for estimating the average temperature in the neighbouring house – based on heat loss, gains & heating type – as per the SAP worksheet. This may give you a 17C average in the old house for example, so there's a 3C average temperature difference between your lovely warm passivhaus and the old one next door. With an average outside temp of 5C or so, (20-17)/(20-5) = 0.2 reduction factor.

Alan

[Nick Grant]

I agree with Alan!

Nick

[Mike Jacob]

Thanks!

[Author]

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