[mvnuweucxqokii]

If it's pretty cold outside, then you're throwing all of the ostensible energy savings of a heat pump out the window the minute you open it to air out the house.

Following the thread of conversation, it just didn't compute to me:

>>>> Heat pumps are great for climate control >>> Yeah, ducts are dead >> What if you want to recirculate air in your house through your central air filter to eliminate smells? > Just open the window

It's like we've hit a contraction: the premise is that we care about energy but the contractions is then that we don't and we open the window while climate controlling the house. So to me it does seem to prove that in some climates, duct work with a central blower and filter mat not be dead.

[ridgeguy]

I think there's a middle ground.

We've just today had our first snow of the season here in a lower elevation of the Sierra Foothills. It's been chilly for 3 months or so, and our heating is an 'old school' ducted propane furnace. In time, we'll replace it with a heat pump, but not this year. Anyway, we're sensitive to accumulated odors that go with a well insulated, closed-up home in winter.

Every evening, we open three doors in the house to the outside. This is after the furnace has entered its timed 'off for the night' state. We exchange pretty much all of our air for fresh ambient, which is great when we wake up in the morning.

The impact from doing this on our propane bill is undetectable. This is because air, even humid air, has a trivial heat capacity compared to the warm house structure and contents. Those are by far the greatest energy reservoir in our home. Very little energy is lost in a daily air exchange with the ambient.

*edited for typo

[fifteenforty]

For an existing dwelling, the best solution is probably mini splits (wall mounted) combined with decentralised heat recovery ventilation as required.

Ducts running in an insulated space are sources of huge energy loss.

[mrexroad]

*uninsulated

[fifteenforty]

Yes correct! Thank you!

[lsaferite]

I'm not sure why "Heat pumps are great for climate control" went to "ducts are dead".

I live in Florida, we've used Heat Pumps for as long as I can remember. We also have central air handlers with blowers and ducts to distribute the conditioned air. Mini-splits can _also_ be ducted mini-splits. According to my HVAC geek friend, mini-splits are pretty terrible about humidity control (an important thing in Florida). For proper humidity control you'd ideally have a dedicated set of dehumidification ducts (powered by a central dehumidifier) as well. Mix in an ERV and you have the ability to build a fairly air-tight house with _controlled_ ventilation and very efficient conditioning of the air in the house.

[fifteenforty]

The Melbourne climate I was referring to needs heating 9 months of the year. The vast majority of houses have very simple, inefficient gas ducted heating. Rightly or wrongly, humidity control is generally not well considered.

I was going to install an ERV system but the payback was not within the life of the equipment.

Someday I’ll build a Passivhaus with a system as you describe.

[daddylongstroke]

No doubt: majority of the southern US went to heatpumps with central air handlers 2-3 decades ago. Ducts are definitely not dead. Or, if they're dead, then they must be as dead as BSD. :-P