Now that I’ve got your attention, was this question a joke?
The answer is: not exactly, although it's all in good humour. The idea is taken from Gunter Lang, an Austrian passive house expert with Lang Consulting.
Lang was speaking at the New York Passive House High Rise Symposium in June last year when I first heard him say this. It was a great way to focus the audience, but why does he say it?
First of all, he says that "sex in a Passive House is safe sex" because the CO2 levels in the air are much lower than for traditional houses. Stale air, moist air and contaminated air are being extracted all the time, and fresh air is being drawn in through the air ventilation unit with its incoming temperature being moderated - even if it's freezing cold or boiling hot outside. The indoor air quality is much better in a passive house than in many other types of house, even if all your windows are closed. You are therefore more likely to be healthier.
You're also less likely to be affected by condensation and mould, because such problems are 'designed out' of a passive house. Mould is well-known as a problem in old houses, but it's not just found in old buildings. Only last week I spoke to a builder in Tasmania who said people were finding increasing mould problems in new buildings. Nobody could understand why.
One reason for this is the nasty effect of thermal bridges, which are embedded into the design of many of our buildings. Also, many of our buildings tend to be 'leaky' because they are not well sealed, which means that moisture can get into the building envelope. Another reason for mould is inadequate ventilation, including the lack of any system which deals with moisture. And if new houses are being sealed up more effectively than in the past, the risk of mould may increase.
All of these issues - thermal bridges, airtightness, and ventilation - are addressed in the design and construction of a passive house.
So if you are less likely to be ill from condensation and mould in a passive house, and you breathe more easily due to the intake of fresh filtered air, then you probably find physical activity a bit easier too.
In addition, the temperatures in a passive house are nice and comfy, without drafts. You can move around the house on a cold night without freezing on your way to the kitchen or bathroom, which is much more relaxing.
Which brings me to another point: low power bills. You don't have to worry about how much your next heating or cooling bill is going to be, because it just takes so little energy to heat or cool a passive house. Nor do you have to worry about the cost of power going up and up. Generally speaking, taking these sorts of stresses out of your life can help you to enjoy other things more.
So yes, Gunter Lang, we see your point. I guess people will not know for sure, though, until they try it!