What are the actual benefits of a 'passive house'?

thank you for your reply. It's great to hear first hand experiences from someone who actually lives in a Passivhaus ?. How does it deal with condensation though? Given that it's relatively airtight? When I bought my own house there was a few patches of 'damp' that were attributed by the previous owners to a failing damp course (my house is 146 years old) but we rectified it by simply increasing ventilation. The previous owners had double glazing installed but none of the windows had vents in them so the damp was in fact caused purely by condensation build up. 

That's where the MVHR comes in.  As the house is so airtight, yes, if there was no ventilation  there would be condensation, stuffiness and eventually breathlessness, I suppose.  The MVHR pushes about 200m3/hr through the house (thanks Andrew, above), which is generally more than you would get with a window open, and ensures that condensation doesn't happen.  Rather the opposite.  We have a sheila/dolly in the utility room.  A load of washing dries on it usually within 12 hours and always within 24hours, winter or summer.  The towels dry in the bathroom. The house is generally on the dry side, being somewhere between 40 and 60%RH.  Unfortunately, it's relatively difficult to retrofit ventilation of this sort, so to get adequate ventilation you lose heat.  I think that all new build should be to PH standard but many housebuilders argue that it's too difficult/expensive.  The last labour gov't brought in the Code for Sustainable Homes with the aim that all new build should be level 6 (PH standard with some extras) by 2016.  But this faded with the coalition gov't and (IMHO) the conservative gov'ts since rolled over to the house builders.  Given the re-emergence of interest in climate change and all things sustainable, this may be changing.  Let us hope so.

thank you for your reply. It's great to hear first hand experiences from someone who actually lives in a Passivhaus ?. How does it deal with condensation though? Given that it's relatively airtight? When I bought my own house there was a few patches of 'damp' that were attributed by the previous owners to a failing damp course (my house is 146 years old) but we rectified it by simply increasing ventilation. The previous owners had double glazing installed but none of the windows had vents in them so the damp was in fact caused purely by condensation build up. 

That's where the MVHR comes in.  As the house is so airtight, yes, if there was no ventilation  there would be condensation, stuffiness and eventually breathlessness, I suppose.  The MVHR pushes about 200m3/hr through the house (thanks Andrew, above), which is generally more than you would get with a window open, and ensures that condensation doesn't happen.  Rather the opposite.  We have a sheila/dolly in the utility room.  A load of washing dries on it usually within 12 hours and always within 24hours, winter or summer.  The towels dry in the bathroom. The house is generally on the dry side, being somewhere between 40 and 60%RH.  Unfortunately, it's relatively difficult to retrofit ventilation of this sort, so to get adequate ventilation you lose heat.  I think that all new build should be to PH standard but many housebuilders argue that it's too difficult/expensive.  The last labour gov't brought in the Code for Sustainable Homes with the aim that all new build should be level 6 (PH standard with some extras) by 2016.  But this faded with the coalition gov't and (IMHO) the conservative gov'ts since rolled over to the house builders.  Given the re-emergence of interest in climate change and all things sustainable, this may be changing.  Let us hope so.