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- CommentAuthorEd Davies
- CommentTimeJun 29th 2012
The Passivhaus standard refers to primary energy demand being less than 120 kWh/(m²·a).
Do they actually mean “primary energy demand” in the sense it's usually used in economics and so on: the energy contained in the originating fossil fuel or whatever so if you use 4 kWh of electricity generated by a plant which is 40% efficient that counts as 10 kWh? Or do they mean energy delivered to the house via the various pipes and wires in the street? -
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CommentAuthorDamonHD
- CommentTimeJun 29th 2012
I hope they mean the former as anything else is mixing apples with oranges, ie 1kWh of electricity is not the same in practical/CO2/money/other terms as 1kWh of gas.
Rgds
Damon -
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- CommentAuthortony
- CommentTimeJun 29th 2012
It wont be long until there is no more gas oil to use compared to the life of a building. -
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CommentAuthorSteamyTea
- CommentTimeJun 30th 2012
Posted By: tonyIt wont be long until there is no more gas oil to use compared to the life of a building.
Plenty of natural gas to see all of us out, and coal, probably oil as well, though that isn't the point.Posted By: Ed Davieshope they mean the former
Yes, this does cause confusion as electricity generated from gas and then used to heat a home via a heat pump as opposed to a restive heater gives very different numbers, as does burning coal in the grate compared to in a large power station to make electricity to run a telly.
Should we distinguished kWh (or MJs) by using kWh(p) for primary energy and kWh(d) for domestic energy use in the home instead of just kWh? Or just let the reader decide. -
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- CommentAuthordjh
- CommentTimeJun 30th 2012
Posted By: Ed DaviesDo they actually mean “primary energy demand” in the sense it's usually used in economics and so on: the energy contained in the originating fossil fuel or whatever so if you use 4 kWh of electricity generated by a plant which is 40% efficient that counts as 10 kWh? Or do they mean energy delivered to the house via the various pipes and wires in the street?
Yes, they follow the usual definition. They specify particular aspects of the calculation so as to get comparable figures between different houses and to minimise cheating. There's pages of stuff in the PHPP manual. The best web expalanation I can turn up in a few minutes is:
http://www.sphc.co.uk/electricity-generation-consumption-passivhaus -
- CommentAuthorEd Davies
- CommentTimeJun 30th 2012
Thanks, djh. Good reference.
For those figures (2.7 for electricity and 1.1 for gas), do you know if they're the same everywhere or whether they've just quoted Scottish figures? It seems to me that they could reasonably vary between countries - e.g., in a nuclear country like France the electricity figure could be a lot lower, perhaps even less than one.
(By the way, ST, it was actually Damon who said “hope they mean the former” but it's not much of a misquote, I'd hope so too.) -
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CommentAuthorSteamyTea
- CommentTimeJun 30th 2012
Strange how the quote thingy glitched, yes I hope so too. -
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- CommentAuthordjh
- CommentTimeJul 1st 2012
Posted By: Ed DaviesFor those figures (2.7 for electricity and 1.1 for gas), do you know if they're the same everywhere or whether they've just quoted Scottish figures?
I believe the 2.7 is a figure used for the whole of Europe based on a DIN standard, but I've seen other things that talk about national agreements. The 2011 revision of PHPP has the 2.7 adjusted to 2.6. You'd need to talk to a certifier to get a full understanding, I think.
(IMHO, PHI could be a lot clearer and more open about details like this - it ought to be trivial to go to their website to discover the answer to a question like this)
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