ENERGY / EER SCORECARD + GLAZING CALCULATOR — 1 Bed Type A

Climate Zone 7 / NatHERS zone 24 (Canberra) · NCC 2022 target 7★ · caps H≤117 · C≤30 · total≤122 MJ/m²·yr · 60 m² · indicative — confirm with the official ABCB xlsx / NatHERS

📋 What is this page? (in plain English)

Every new home in Australia must reach an energy rating — a score out of 10 stars for how comfortable and cheap-to-run it is. New homes have to hit 7 stars, and Canberra gets cold winters, so the house has to hold its heat.

Picture the house like a person in winter: the insulation is the jumper (thicker = warmer), and the windows are the thin bits where heat escapes fastest. The goal is to keep it warm without burning lots of power. This page is our working-out — how we check the design before we build:

① Windows — windows leak the most heat, so the rules limit how "leaky" they can be. We add ours up and check they're under the limit (better glass = double glazing = less leak).
② Insulation — the roof, walls and floor each need a target amount of insulation (an "R-value" — bigger number = warmer). Green PASS = we've met it.
③ Total heat loss — everything added into one number. Lower = warmer home = better score. Ours sits in the ~7-star range.

The honest bit: the official star is produced by government-approved software run by an accredited assessor (or the official ABCB spreadsheet, linked below). This page gets us as close as we can on our own — we design it to pass, then the expert confirms it. No surprises.
Have a go: change any number in a box (like the window quality) and the whole sheet updates — you can watch what makes a home warmer or colder.

💡 Worth the effort: spend the time getting this right here, and it saves a lot of back-and-forth with the assessor later.

Global inputs: Air changes/hr

Floor: concrete slab-on-ground — slab-edge insulation (R1.0) to Zone 7; the slab's thermal mass stores winter solar gain & evens out temperature swings — a plus for the star rating (captured by NatHERS, not by this steady-state UA).

1 · External glazing — DTS calculator (NCC 2022 Pt 13.3, "% of allowance" method)

Each opening uses part of a Conductance allowance (A×U_w) and a Solar-gain allowance (A×SHGC×shading). Totals must stay ≤100%. Edit cells to test; shading = fraction of solar admitted (1 = none).

Opening	Orient.	W	H	Area m²	U_w	SHGC	Shade	A·U (W/K)	A·SHGC·sh
TOTALS

Solid entry door excluded (counted as wall/door, not glazing). The W3 slider is glazed → included.

Allowances (← enter the official ABCB Zone-7 figures from the spreadsheet; seeded with indicative placeholders):

Conductance allowance (W/K) Solar-gain allowance (m²)

Conductance used
Solar gain used

Indicative — the allowance constants are zone-specific and live in the official ABCB sheet; the per-opening inputs above transcribe straight into it. ↓ Download the official ABCB NCC 2022 Vol Two glazing calculator (.xlsx)

2 · Elemental DTS compliance (deterministic — Zone 7)

Element	NCC req.	Provided	Status
Ceiling / roof	R6.0	R6.0 (300 rafters)	PASS
External walls	R2.8	R2.5 + refl. wrap/cavity ≈ R2.8	PASS
Floor — concrete slab-on-ground	edge insul. (Z7)	R1.0 edge + mass	PASS
Building sealing	draught-sealed	spec'd	PASS
Glazing	§1 calculator	see §1	—

3 · Envelope conductance (UA) — live

Element	Area m²	U	W/K	% loss
TOTAL
per m² floor (UA/A)

Fabric quality: (UA/A proxy: ≤1.6 ~8★ · 1.6–2.0 ~7★ · 2.0–2.4 ~6★ · >2.4 <6★ — not an official NatHERS output)

4 · 7-star lever scorecard

✅ Major glazing NORTH + 600 eave (winter in / summer shaded) · ✅ no E/W glass · ✅ R6/R2.8 + slab edge insul. · ✅ DG low-E (U_w≤2.0) · ✅ compact 60 m² sealed · ✅ concrete slab = high thermal mass (passive-solar coasting, +★)

Judgement: on track for ~7 stars (6.5–7.5).

Why no certified MJ/m² star here: the dynamic north-solar gains + thermal-mass coasting that decide the star are only captured by the NatHERS sim (a steady-state calc reads ~2–3★ low for passive-solar). This sheet does the two things we can do deterministically — the DTS elemental checks and the glazing calculator structure. Finish with the official ABCB glazing xlsx (DTS path — free, no sign-in) or a prelim NatHERS (~$300).