[dirkf]

I live in a passive house in western Europe; AMA :)

So far autumn has been fairly mild and quite sunny. As far as I know our (floor) heating has not had to kick in, or if it did it has been limited. I was still walking around in T-shirt + shorts until well into October. So yeah, I can confirm passive houses work, and I'm glad they do with the current energy prices.

When we built our house such passive houses were rare. Nowadays basically every newly built house should be (more or less) passive due to regulations that were tightened every couple of years. But there are still many many old and very energy inefficient houses that are in need of a good renovation...

[mattcantstop]

How have you liked your floor heating for performance, cost, and comfort?

[dirkf]

Performance wise floor heating has no problem with keeping a well insulated house warm; it doesn't have to be a passive house for that.

Comfort wise I think floor heating is the best. It's radiated heat instead of heat from hot air circulating around, and since it's coming from below it tends to give you a more evenly feeling of warmth across the whole room/house.

Comparing cost is difficult... you have to look at the complete picture of all equipment you need in the house: how do you produce the heat? Is the same appliance also used for heating your tap water? How do you ventilate your house? Do you want/need some way to cool the house during summer?

We've chosen a geothermal heatpump that handles both heating the house and the tap water. Since we don't need much heating capacity the additional cost compared to the commonly used (at that time) gas heater was manageable. Additional benefits:

- Gas/oil heaters require a mandatory (bi-)yearly maintenance/checkup while a heatpump doesn't. - Using only electricity as energy source means I only have to pay one set of installation cost + yearly fixed subscription cost. - Electricity I can generate locally on my roof. - The heatpump can also be used for cooling via the floor heating system. It's not the same as real A/C but on the other hand it costs way less energy (basically just running the circulation pumps).

[cafard]

What is your air circulation like?

[dirkf]

It's a balanced mechanical ventilation system with a heat exchanger and located in the attic. It pulls in fresh air via an inlet on the roof and then distributes it via a set of tubes to the various rooms. Similarly, it extracts stale air via other tubes from other rooms to the outside through an outlet elsewhere on the roof.

Both airflows pass the heat exchanger so the outgoing air can heat up the incoming air to minimize heat losses. These airflows are balanced, i.e. the various inlets/outlets in the rooms are calibrated so the total inflow matches the total outflow without the fans in the device having to run at different speeds.

An alternative system that is frequently used here is mechanical extraction while fresh air is pulled in 'naturally' via slits at the top of the window frames. This is obviously cheaper but has some disadvantages:

- The incoming air is cold and thus your heating system needs to work harder to keep the temperature constant. - You can feel this cold air flowing in, typically around your feet and this can be uncomfortable. - Less control over how much air flows in: a bit of wind outside can mean more (cold) air is blown into your house. There are sliders on these slits but they are manual so people either keep them open (resulting in more incoming air than strictly needed) or they close them (resulting in too little ventilation).