NCC 2022 and solar in new Perth homes: what the building code now requires

From 1 October 2023, WA adopted the National Construction Code 2022 (NCC 2022) energy efficiency provisions for new Class 1 residential buildings (houses and townhouses). The changes significantly raised the minimum energy performance requirements and included new provisions for electric vehicle charging and on-site generation. Here's what it means for Perth homeowners building new.

The headline change: 7-star NatHERS minimum

NCC 2022 raised the minimum NatHERS (Nationwide House Energy Rating Scheme) star rating for new Class 1 homes from 6 stars to 7 stars. NatHERS assesses thermal performance of the building shell — how well the home maintains comfortable temperatures without mechanical heating or cooling.

What 7 stars means for Perth homebuilders: Perth's climate zone (Climate Zone 5 — warm temperate) means that achieving 7 stars typically requires:

• Improved ceiling and wall insulation (R3.5–R4.0 ceiling, R2.0–R2.5 wall insulation)
• Thermally broken aluminium framing or uPVC frames for windows in exposed locations
• Lower solar heat gain coefficients (SHGC) for west and north-facing glazing
• Adequate natural ventilation pathways for cross-ventilation

Most established Perth volume builders (Celebration Homes, Dale Alcock, Retreat Homes, Ventura, BGC) have updated their standard specifications to achieve 7 stars for their standard designs since October 2023.

The "whole-of-home" cap: where solar connects

NCC 2022 introduced a whole-of-home energy use budget alongside the NatHERS thermal shell rating. This is new — it expands assessment beyond the building shell to include the energy consumption of fixed appliances and services.

The whole-of-home budget covers:

• Space conditioning (air conditioning and heating)
• Hot water systems
• Fixed lighting
• Pool and spa pumps (if installed at building time)
• On-site renewable generation (solar panels)

How solar interacts with the budget: Solar generation offsets the whole-of-home energy budget. A home that wouldn't achieve the whole-of-home cap purely through efficiency can use solar generation to reduce the net energy requirement. This creates a direct pathway where solar helps a home meet NCC 2022 requirements.

In practical terms for Perth: a home with good insulation and a heat pump hot water system might reach the whole-of-home cap without solar. A home with a larger AC unit or gas hot water may benefit from adding solar to meet the cap.

EV charging readiness provisions

NCC 2022 Part J2.2 introduced EV charging readiness requirements for new Class 1 homes with garages. The requirement is to provide:

• A conduit (typically 32mm or 50mm) from the main switchboard to the garage
• Tagged and documented on the as-built plans

This is a conduit-only requirement — not a charger, not a dedicated circuit, but a pathway that makes future EV charger installation cheaper. For Perth homebuilders, this means any new home with a garage built after October 2023 should have an EV conduit from switchboard to garage as a standard inclusion.

If your builder's contract doesn't mention this and your home was built (or is being built) under NCC 2022, ask directly whether the conduit has been installed and whether it's documented on the electrical certificate.

Batteries are not required (but complement NCC 2022 homes well)

NCC 2022 does not require battery storage. However, NCC 2022-compliant homes are well-suited to battery storage for several reasons:

Lower heating/cooling loads: A 7-star shell heats and cools more efficiently, meaning AC consumption is lower and a modest battery can cover more of the evening peak load.

Solar-ready design: The whole-of-home budget framework creates an incentive to include solar at build time. A home designed with solar already factored into the energy budget is also an easy candidate for battery addition.

EV conduit already installed: The mandatory EV conduit means battery and EV charger installation is cheaper post-build — reduced labour for cable runs.

Practical implications for Perth homebuilders

Volume builders: Standard designs now include higher insulation levels, upgraded glazing, and in some cases solar-ready electrical specifications. Ask your builder specifically what their 7-star compliance strategy is for your design — some builders achieve 7 stars through high-specification glass and insulation alone, others rely partly on solar panels.

Custom builders: Engaging an architect or designer to achieve 7 stars opens more flexibility. A well-oriented home (living areas facing north, minimal west-facing glazing, appropriate roof overhangs for Perth's sun angles) can achieve 7 stars with standard insulation rather than premium glazing. Thermal mass (concrete slab, brick walls) combined with cross-ventilation is highly effective in Perth's climate.

Builder compliance documentation: Your building approval includes a NatHERS certificate (from a licensed NatHERS assessor) and a whole-of-home assessment. Ensure you receive these documents — they form part of the property's compliance record.

What NCC 2022 does NOT change

Existing homes: NCC 2022 applies to new construction only. Existing Perth homes are not required to upgrade to meet CC 2022 standards.

Gas appliances: NCC 2022 does not prohibit gas appliances in new homes. However, the whole-of-home energy budget framework disadvantages gas relative to electric alternatives (heat pumps, induction cooktops) in terms of carbon intensity. WA state government has not adopted a gas ban for new residential construction as of 2026.

Solar system requirements: NCC 2022 does not mandate solar on new homes — it creates a framework where solar can help homes meet the whole-of-home energy budget. There is no minimum solar system size or inverter requirement.

Questions to ask your builder about NCC 2022

1. How does this design achieve 7-star NatHERS? (insulation only, or does it rely on solar?)
2. What whole-of-home energy budget pathway does this design use? (what appliances/systems are assumed?)
3. Is solar included in the base price, or is it additional?
4. Has the EV charging conduit been included in the electrical specification?
5. Can I see the NatHERS certificate before signing the contract?

NCC 2022 raised the minimum NatHERS rating to 7 stars for new Perth homes (from October 2023) and introduced a whole-of-home energy budget that allows solar generation to offset appliance energy use. It also mandates EV charging conduit in garages. For Perth homebuilders, these requirements push toward better-insulated homes with solar-ready electrical systems — a foundation well-suited to adding battery storage and EV charging down the track.