Zoned ducted or multiple split system air cons

I'm building a new house in Victoria and struggling to figure out if a zoned ducted electric heating and cooling or having 3 or possibly 4 separate air conditioner units will be more efficient? It will mainly be used for heating. We only use air con for a coupleof days per year now. 250sqm living 4 bed 2 lounge mostly open plan house.
Thanks!

Hi

I might not be much help, but in a similar situation to you and have done some research. So far there seem to be pros and cons for each.

For multi splits, better control of temp in each room and can do heat/cool individually. If you get a sensibo or similar controller or purchase splits with wifi you can control from your phone, set schedules, timers etc. I've got a few splits and sensibo controllers for each and the control is incredible. I don't even pay for the subscription, but i use home assistant to do some of the more complex automations. Split systems means that if one condenser goes down, the whole house won't go down with it. Only drawback is having multiple condensers means more breakers required on your board.

For a large, ducted unit, some of the more expensive units have good zone control which means setting individual temps per room (similar to the above), only requires one single large, dedicated breaker on your board and if there is ample space above your ceiling then running ductwork is easy. The only problem if the condenser goes down/has a problem it affects your whole house. The whole house unit is likely to be cheaper to run, but not by a whole lot.

If i was doing a new build and had space, i would consider having MVHR (MVHR - Mechanical Ventilation with Heat Recovery - Energy Recovery [Heat Recovery] - MVHR - Fantech or MVHR buyers guide - Renew) which will provide a much more comfortable house in general. The only drawback is the unit, and ductwork must be within the building insulated envelope. That means ducts running through walls or bulkheads and having a mechanical unit indoors.

For my situation (extension to an older house) I'm going with multiple splits as the duct runs from where the main central a/c unit is located are too far and I'd have to add bulkheads to the "old" part of the house which has original cornices etc. I don't want to do that.

Hope that helps, good luck.

A multi head split or VRF system is the most efficient especially if you dont intend to condition the entire house and you want to target a certain room.
Ducted systems are still an efficient form of heating if concealing the system is of interest or you can use a bulkhead spit system.
Personally though I prefer a ducted system with a individual room sensors, fresh air intake and a control system like MyAir or similar.

Saw this video yesterday, worth a look to help you decide: Splits vs Ducted Heating and Cooling Systems - Building Envelope