10 PH Myths

Dr.Wolfgang Feist

Interview with Dr. Wolfgang Feist who dispels some myths about Passive Housing

1. You can’t open the windows in a passive house.
On the recommendation of the PHI (Passive House Institute) every passive house has windows which can be opened. The technical house ventilation system brings fresh air in, so you won’t ever find any stale air in the house, even if you don’t open the windows for an extended period e.g. during cold rainy weather.
2. Due to controlled living-space ventilation there is a draught.
The ventilation of the living space “ventilates” just as much as is necessary for sanitary first-class air quality. It’s best to build air exhausts at ceiling height, and therefore from as little a distance as 30 cm away the air flow will no longer be noticeable; you won’t feel any draughts in passive houses.
3. A PH has no heating.
As a rule a passive house needs only a small heating installation, but it isn’t a ‘zero heating energy house’. Yes, a passive house has heating.
4. A PH is always rather “clumsy”.
Where does such a statement come from? There are thousands of passive houses in different shapes and sizes: from partial hip roof houses, to those like truncated cylinders and cones, to those in wankel-piston form. There is a wide variety available.

5. The technology is still in development.
A passive house doesn’t require as much technology as a conventional house! The only special technology which is needed is house ventilation with heat recovery, and this has been successfully used in Canada and Scandinavia for over 50 years.
6. You can only build a PH on a sunny site.
Well, this opinion might be the result of a mix-up with the “passive solar” approach. You will find passive houses on inner-city premises with the house facing north. A shaded site is no excuse not to build a passive house.
7. A PH is much more expensive than a conventional house – it doesn’t pay off.
Our last inquiry showed four to eight % more investment was required initially. You also have to factor in higher financial aid due to the positive environmental nature of the house. The most impressive result comes later: residents will save between 800 and 1500 Euros in running costs every year. If you calculate this rationally and look ahead, you will see that you really can’t afford a less efficient house.

Passive House in Austria

8. A PH is always cold.
There is only one thing you can do: go and visit a passive house. Inhabitants of passive houses like the warmth; we have measured temperatures between 22 and 24° C in winter. This is affordable, as heating a passive house doesn’t cost a lot.
9. Separate rooms can’t have different temperatures in a PH.
That is up to the inhabitants: you don’t really need cold side rooms if it costs little to keep them warm, and a cool wine cellar can be built into a passive house, if required. Almost anything is possible.
10. You can’t redevelop an old house into a PH.
This is generally true, but it’s only half the story: you can build passive house technology into an old building – it takes good exterior insulation, triple glazing and ventilation with heat recovery. You won’t reach the energy standard of a passive house (with its 15 kWh/(m²a)), but you will get between 20 and 35 kWh/(m²a). Be clear about this though: real passive house redevelopments are possible, even for bigger properties.

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