NCC 2022 Energy Efficiency for Residential Buildings (7-Star NatHERS)

What it is

The energy efficiency provisions for new Class 1 buildings sit in Part H6 of NCC Volume Two. NCC 2022 raised the minimum thermal performance to the equivalent of a 7-star rating under the Nationwide House Energy Rating Scheme (NatHERS), up from 6 stars in NCC 2019. It also introduced a whole-of-home annual energy use cap that covers heating, cooling, hot water, lighting and pool or spa equipment.

The intent is plain. A new house has to use less energy across its useful life. The Performance Requirement H6P1 deals with the building fabric. H6P2 deals with the whole-of-home energy use budget.

How to comply

Two Deemed-to-Satisfy pathways exist.

Option 1: Energy rating (NatHERS)

A registered NatHERS assessor models the building in approved software (FirstRate5, AccuRate, BERSPro or HERO). The model has to return a minimum 7-star rating against the NCC reference standard. Climate zones 1 and 2 (tropical and warm humid) carry a concession to 6 or 6.5 stars where the home has a covered outdoor living area meeting minimum R-value and a permanent ceiling fan. The model output (the NatHERS Universal Certificate) becomes part of the permit set.

Option 2: Elemental provisions

The builder follows the prescriptive insulation, glazing, sealing and shading rules in Section 13 of the ABCB Housing Provisions. No software is needed. The rules are tighter than they were in NCC 2019 and the floor and wall R-values shift with climate zone.

For both pathways, the whole-of-home energy use is calculated separately. Annual energy use is capped against a benchmark that varies by climate zone and dwelling size. A heat pump hot water system and induction cooking typically help the budget. Resistive electric hot water typically does not.

Where this gets missed on site

The biggest gap is between the rating used to get the permit and the house actually built. A NatHERS assessor models a slab-on-ground with R1.0 edge insulation, R2.5 wall batts and R6.0 ceiling batts. On site the wall batts go in at R2.0 because the supplier is out, the ceiling batts get compressed around downlights, and the slab edge insulation is omitted entirely.

A second gap is building sealing. NCC 2022 calls for specific weatherproofing and air sealing at penetrations, perimeters and service entries. Most residential builders do not pressure-test (a blower door test is rare on Class 1). A house can lose half a star or more to leakage that the rating did not predict.

A third gap is glazing substitution. The original schedule calls for double-glazed argon-filled units with a specified U-value and SHGC. A late-stage cost cut substitutes single-glazed aluminium frames. The rating is no longer valid but the permit is never reissued.

Rectification cost magnitude

Insulation rectification on a finished house (lifting roof tiles or sheets, top-up batting, re-flashing) costs $4,000 to $12,000 for a single-storey detached home. Slab edge insulation cannot be added after the slab is poured. Replacement glazing for compliance ranges from $1,200 to $3,500 per window, plus reveal and architrave rework. The most expensive case is a whole-of-home re-rating that requires changes to multiple elements at once.

What an auditor inspects

For TradeLens, the audit trail is the NatHERS Universal Certificate (or Section 13 compliance schedule), insulation product certificates with R-value declarations, the glazing schedule cross-checked to product data sheets, and photographic evidence of insulation install before plasterboard. The whole-of-home calculation should match the hot water unit, cooking appliance and HVAC equipment actually installed.

A builder who reads the rating before the slab pour and protects the spec through to lock-up gets through energy compliance audits cleanly. A builder who treats the rating as paperwork hits expensive rectification at occupancy.