You're paying top dollar for a brand new home. A few years in, you're still running the air conditioning half the year and wondering why the power bill looks like it belongs to a house twice the size.
New homes should be the most efficient homes we've ever built. Plenty are. But a lot of project homes still do the bare minimum on paper and less than that on site. As the person paying the mortgage and the power bills for the next 30 years, you're entitled to ask why.
The minimum just went up, and that's good
Under NCC 2022, most new homes now need a 7-star NatHERS rating, up from 6 stars. Queensland adopted the new energy efficiency requirements from 1 May 2024. There's also a whole-of-home energy budget covering major appliances like your hot water, air conditioning and pool pump.
That's progress. But two problems remain:
- The minimum is the target. Most project builders design to scrape over the line, not to make the home genuinely comfortable or cheap to run.
- The rating is on paper. A NatHERS rating assumes the insulation, sealing and glazing are installed as designed. If the batts are squashed, gaps are left or the windows are swapped for cheaper ones, the house you live in won't perform like the house that was rated.
Where new homes leak energy
Insulation that's missing, compressed or gappy
Batts that are squashed behind services, missing around downlights or pushed aside by the electrician lose a big chunk of their rated performance. In a hot Queensland roof space, every gap counts.
Air leaks
Gaps around windows, doors, downlights, exhaust fans and service penetrations let cooled air out and hot air in. Proper sealing and weatherstripping aren't expensive. They just take care, and care takes time on a schedule that's built around speed.
Glazing
Standard single-glazed windows in aluminium frames are often the cheapest way to meet the rating, especially when they're small. Big west-facing glass without shading is a recipe for a hot house in the afternoon, whatever the star rating says.
Orientation and shading
Project homes are often designed once and plonked on any lot, whichever way it faces. North-facing living areas with eaves sized to block the high summer sun and let in the low winter sun are the easiest to keep comfortable. Living areas on the west with no shading cop the full afternoon heat.
Dark roofs and missing eaves
Dark roofs absorb a lot more heat than light ones and push up the load on your air conditioning. Removing or shrinking eaves saves the builder money and costs you comfort.
Thermal mass in the wrong place
A concrete slab isn't the problem. A shaded slab in a well-designed home can help keep it cool by soaking up heat during the day. A slab baking in direct summer sun through unshaded glass is a different story.
"It's the best value for money"
Ask your builder why they use a particular window, insulation or roof colour and you'll often hear "it's the best value for money". Says who?
Value is subjective. If you only count today's purchase price, the cheapest option always wins. If you count purchase price, maintenance and the cost of running the house for 30 years, the cheapest option often loses.
So ask yourself: would you rather pay now or pay later? A bit more insulation, better glazing or wider eaves at design stage costs far less than retrofitting them, and much less than decades of higher power bills.
Why builders stick to the minimum
Project builders compete on headline price. Every dollar spent beyond the minimum is a dollar that makes their ad look more expensive than the builder next door. Many project builders and their industry associations resist change because it threatens predictable margins.
It makes no sense to me that we rate fridges and TVs on their energy use, yet we're still fighting about the efficiency of the largest energy-consuming thing most of us will ever buy.
The good news: you don't need to wait for regulation. You just need to ask better questions.
Questions to ask your builder
About the rating
- What NatHERS star rating does this design achieve on my lot, facing the way it actually faces?
- What would it cost to reach 8 stars? Which changes give the biggest gain for the least money?
- Can I see the NatHERS certificate and the assumptions it relies on (insulation R-values, glazing, roof colour)?
- How will you make sure the as-built home matches the rated design?
About the design
- Can the living areas face north?
- What size are the eaves, and do they shade the north and west windows in summer?
- What glazing are you using, and what are its U-value and SHGC (solar heat gain coefficient)?
- Can we have a lighter roof colour?
About the build
- What insulation goes in the ceiling and walls, and who checks it's installed properly before the plasterboard goes on?
- How will you seal around windows, doors, downlights and penetrations?
- What hot water and air conditioning systems are included, and what are their energy ratings?
About value
- If solar panels, a heat pump or better glazing aren't standard, what does it cost to add them now rather than later?
Check it on site
The best specification in the world doesn't help if it isn't installed properly. Check insulation, wall wrap and sealing at the stages where you can still see them. Our C7 Frame, C10 Rough In and C11 Enclosed checklists cover wrap, penetrations, and insulation before it disappears behind the plasterboard.
The bottom line
Seven stars is now the minimum, not a premium. A home that's genuinely comfortable and cheap to run comes from good orientation, shading, insulation installed properly and a builder who cares about what happens after handover.
Ask the questions, get the answers in writing and check the work on site. You're the one paying the bills, so don't settle for a sieve.
