In general, this conclusion comes from the notion that a passive house has fewer moving parts and requires less attention. A poorly insulated house demands that you take more active measures to ensure that it keeps a positive temperature (so water pipes don't freeze), this is extra pertinent should the power go out. A well-insulated house is also likely to have fewer points of failure (water getting into cracks and whatnot).
A proper passive house generally only has one maintenance point, which is the ventilation / air filtration system, and temperature control is easy. You don't have to worry much about the insides being too hot or too cold, as it should keep whatever temperature you set regardless of the weather outside.
With all that said, you should generally take everything I said with a grain of doubt, as I'm not an expert, and someone could well shoot down all my points in the comments. ;-)
My prime goal with any house I buy is to make sure that I have to do as little as possible; never worry about water being in the wrong place, and never worry about the power bill, or temperature in general.
First of all, if you build a PassivHaus in normal climate (not cold) you will be amazed to see that you do not need a heat pump, you can just use normal electric boiler for hot water and use electric underfloor heating mats for heating, or infrared panels mounted on the roof.
On the other side, air-to-air heat pumps have gotten cheaper by the year, you can buy a decent heat pump (NIBE) with about 4500-5000 euros.
Electric boilers are extremely energy inefficient compared with heat pumps. If you built a Passive House, not going the extra mile for a heat pump seems silly to me. Not to mention that heat pumps can easily protect you against heatwaves (should any happen).
Exactly what coryrc said in his comment, for a PassivHaus you recover very slowly the cost of the heatpump and if it brakes once in 10-15 years while it takes to recover the investition... you will never recover it.
Personally I've addressed that concern with a CO2 alarm in every room (which you should have regardless, so I don't count that against passive houses). I suspect that there exist ventilation fallback solutions that can address a power failure scenario, but I've yet to find any viable ones.
It should be possible to have a system that generates automatic airflow should power fail.
Best ones I've found are solar panels, or geothermal power generator (geothermal is generally really amazing for everything), but that still leaves mechanical failure.
That said, it takes quite a bit of time before ventilation failure leads to a dangerous CO2 buildup. And the addition of having a single entry point for air means that it's easy to filter my air through a HEPA filter, ensuring top quality air all year round.
A proper passive house generally only has one maintenance point, which is the ventilation / air filtration system, and temperature control is easy. You don't have to worry much about the insides being too hot or too cold, as it should keep whatever temperature you set regardless of the weather outside.
With all that said, you should generally take everything I said with a grain of doubt, as I'm not an expert, and someone could well shoot down all my points in the comments. ;-)
My prime goal with any house I buy is to make sure that I have to do as little as possible; never worry about water being in the wrong place, and never worry about the power bill, or temperature in general.