New build heating and cooling in the Cardinia growth corridor.

The Pakenham East and Officer precinct structure plans are putting thousands of new homes into this corridor, and the houses going up now are fundamentally different machines to the 2002-to-2008 estate homes around Cardinia Lakes and Heritage Springs. Two changes drive it. The National Construction Code lifted the residential energy requirement to 7 stars, so glazing, insulation and envelope tightness all stepped up. And Victoria has moved new homes requiring a planning permit to all-electric, while the Victorian Energy Upgrades scheme now pays nothing at all to install new gas.

The upshot for you: a genuinely 7-star house in NCC climate zone 6 needs meaningfully less heating and cooling capacity than a 6-star house of the same footprint. Smaller equipment, cheaper to buy, cheaper to run. But a tight house is far less forgiving of bad zoning and bad sizing than a leaky one was, and this is where the standard builder package tends to fall over.

Reading the builder's specification.

The base heating and cooling package in a volume-builder contract is normally sized to the minimum that satisfies the energy report, not to what the house actually needs on a 42-degree northerly with the sun on the western glass. Three things are worth checking before you sign:

• Actual kW rating against a real heat load. Not floor area times a multiplier. A room-by-room calculation on your orientation, your glazing schedule, your insulation and your ceiling heights. A 240 square metre double-storey in Pakenham East typically lands at 14 to 18 kW; if the package says 10 kW, ask why.
• Zone count. Two zones on a four-bedroom double-storey is a false economy. You will heat the bedrooms all day and cool the living all night. Four to six zones is the honest number, and adding them later means re-opening the ceiling.
• Duct sizing and insulation. R1.0 is the floor. R1.5 is what you want in a Cardinia roof cavity that hits 60°C in February. Duct sizing to AS 4254.2 with the return air actually sized for the airflow, not a 400 mm grille feeding a 16 kW unit.
• Condenser position against your covenant. Most of the new Cardinia estates carry design guidelines requiring services not be visible from the street frontage. The builder will comply, but the position they pick may be the one that puts the condenser under your own bedroom window.

If the package is honest, take it. It is bundled into your loan at builder's pricing and that is genuinely hard to beat. If it is a 10 kW unit with two zones on a big double-storey, upgrading at handover will cost you more than negotiating it now. We will review the specification for you and tell you which one it is, and that review costs you nothing.

Frame stage versus after handover.

For ducted, during construction wins and it is not close. Running flex, setting the plenum and placing return air in an open frame before the plaster goes on is dramatically faster than crawling a finished roof cavity, and the ceiling penetrations are cut once rather than cut and patched. A ducted reverse-cycle installed at frame stage in a Pakenham estate typically runs $13,000-$18,000; the same system retrofitted after handover is $13,000-$22,000 and takes longer.

For splits it is the opposite. There is no real penalty to fitting a split after handover, and you usually get a better price and a free choice of brand doing it yourself rather than taking whatever the builder has a supply deal on. Our split system page covers what a post-handover install involves.

The practical constraint is that most volume builders will not allow another trade on site before handover, for insurance and warranty reasons, and trying to force it can void parts of your build warranty. So your real choices are: upgrade the builder's own line item, or delete heating and cooling from the contract and install after handover. Both are legitimate. Which is better depends entirely on how honest their base spec is.

All-electric, solar and the switchboard.

Nearly every new Cardinia home now goes up with a rooftop solar array, and a ducted reverse-cycle inverter pairs beautifully with it - running the system on solar surplus in the middle of a hot February day is effectively free cooling. Three things to get right at build stage while it is cheap. Switchboard capacity, because a ducted RC inverter draws 25 to 40 amps on start and you also want headroom for an EV charger later. The interaction between the air conditioning load and the solar inverter under AS/NZS 4777.2, including United Energy's export limit for your connection. And main supply sizing, which is trivially cheap to upsize while the trench is open and expensive afterwards.

Going all-electric also drops the daily gas supply charge - roughly $1.10 a day, about $400 a year - for a connection you would barely use. And a ducted reverse-cycle with a published heating COP of 4.0 or better returns roughly $4 of heat for every $1 of electricity, which is the number that makes the running cost work through a Pakenham winter.

The reactive clay factor.

Much of the Cardinia corridor sits on reactive clay, and new estate sites are commonly classified M or H1 under AS 2870. That matters to us in two places. Condenser pads: a slab pad on unprepared reactive clay will move seasonally, and a condenser that has tilted is a condenser with a compromised condensate path and a fatiguing line set. We bed condensers properly. And plenum and duct connections: seasonal frame movement works connections loose over the first few years, which is one reason a two-year post-handover check is worth doing on a new build even though nothing is obviously wrong.

2026 new-build costs - Pakenham.

Ducted reverse-cycle at frame stage, four to six zones: $13,000-$18,000. The same retrofitted post-handover: $13,000-$22,000. Additional zones on the builder's package: typically $450-$900 per zone at frame stage, far more later. Ducting per metre where you are upgrading the spec: $120-$180, including R1.5 to R2.0 insulation. Splits after handover: $1,800-$2,800 for an easy 2.5 to 3.5 kW back-to-back, $2,400-$3,800 for a 5 to 7 kW, $3,200-$5,200 where a double-storey high wall needs a lift.

Worked example from an Officer build. Builder's package: 12 kW ducted, two zones, R1.0 flex, $14,200 in the contract. Our heat load on the actual plans said 16 kW for that orientation and glazing, and four zones was the honest minimum for a two-storey with three bedrooms upstairs. The builder's upgrade to 16 kW plus two extra zones plus R1.5 flex came to $3,600 on the variation - so $17,800 all up, in the loan, done at frame stage. Deleting and retrofitting the same scope after handover was quoted at $19,400 and would have meant a summer without cooling while they waited. Take the variation. That is what a review is for.

Should I take the builder's standard heating and cooling package in a Pakenham new build?

Read the specification before you decide, because the base package in a volume-builder contract is normally sized to the minimum that satisfies the energy report, not to what the house needs on a 42-degree northerly. The three things worth checking are the actual kW rating against a room-by-room heat load rather than a floor-area rule of thumb, the number of zones, and the duct sizing and insulation R-value. If the package is honest, take it - it is bundled into your loan at builder's pricing and that is hard to beat. If it is a 10 kW unit on a 240 square metre double-storey with two zones, upgrading at handover will cost you more than negotiating it now.

What does 7-star NatHERS mean for my heating and cooling in Officer or Pakenham East?

The National Construction Code lifted the residential energy efficiency requirement to 7 stars, which in practice means better glazing, more insulation and a tighter envelope on every new Cardinia house. The good news is that a genuinely 7-star house in climate zone 6 needs meaningfully less heating and cooling capacity than a 6-star house of the same size, so your equipment can be smaller and cheaper to run. The trap is that a tight house punishes bad zoning and bad ventilation much harder than a leaky house did. Get the heat load done on your actual plans and orientation, not on a rule of thumb, or you will end up with an oversized system short-cycling and never controlling humidity.

Is it cheaper to install ducted during construction or after handover in Pakenham?

During construction, and it is not close on a ducted system. Running flex, setting the plenum and placing return air in an open frame before the plaster goes on is dramatically faster than crawling a finished roof cavity, and the ceiling penetrations are cut once rather than patched. A ducted reverse-cycle installed at frame stage in a Pakenham estate typically runs $13,000 to $18,000; the same system retrofitted after handover is $13,000 to $22,000 and takes longer. Split systems are the opposite - there is no real penalty to fitting them after handover, and you often get a better price and a free choice of brand by doing it yourself.

Can I use my own installer instead of the builder's on a new Cardinia home?

For work inside the building contract during construction, usually not - most volume builders will not allow another trade on site before handover, for insurance and warranty reasons, and trying to force it can void parts of your build warranty. What you can normally do is delete the heating and cooling from the contract entirely and have it installed after handover, or negotiate an upgrade on the builder's own line item. We are happy to review the builder's specification for you and tell you honestly whether it is worth upgrading with them or deleting and doing it properly after handover. That review costs you nothing.

Does a new Pakenham house still need gas ducted heating?

No, and increasingly it cannot have it. Victoria has moved to require new homes requiring a planning permit to be all-electric, and separately the Victorian Energy Upgrades scheme now pays nothing to install new gas. For a 7-star house in Pakenham, a ducted reverse-cycle inverter with a heating COP of 4.0 or better delivers roughly $4 of heat for every $1 of electricity, and pairs with the rooftop solar that most new Cardinia homes are fitted with anyway. Going all-electric also means you drop the daily gas supply charge, which is roughly $1.10 a day, or about $400 a year, for a connection you barely use.

Related reading: ducted refrigerated cooling for how we size and zone, the best time of year to install if your handover date is flexible, and noise rules and covenants for the condenser position question. Local detail on Officer and the wider Cardinia Shire.