If you're building a new home in Canberra, you are legally required to meet a minimum 7-star Energy Efficiency Rating (EER). If you're renovating or extending an existing home, it depends on the scale of the work - and it can catch people off guard.

I'm Jeff Rentoule. I've been building homes in Canberra for years, and energy efficiency is one of the topics I get the most questions about. Not because people are excited about compliance paperwork - but because they want to know what it's going to cost them, and whether it's actually worth it. Here's my honest take.

What Is an EER and Why Does It Matter in Canberra?

An Energy Efficiency Rating (EER) is a star rating that measures how much energy a home needs to heat and cool to maintain a comfortable temperature. The scale runs from 0 to 10. The higher the star rating, the less energy required.

Canberra sits in Climate Zone 7. That makes it one of the coldest capital cities in Australia. We get genuine winters here - frosts, sub-zero nights, months where your heating runs almost constantly. That's why EER matters more in Canberra than it does somewhere like Brisbane or Sydney. The energy your home wastes in winter isn't an abstract number. It shows up on your power bill every month.

The ACT is also the only jurisdiction in Australia that requires an energy rating for existing homes at the point of sale or lease. That means if you're buying or renting a home in Canberra, you should see an EER on the listing. If you're selling, you're required to disclose it.

The 7-Star Requirement for New Builds

Since October 2023, all new dwellings in the ACT must meet a minimum 7-star EER under the updated National Construction Code (NCC). The previous standard was 6 stars.

That one-star increase sounds small. It isn't. A 7-star home requires roughly 25-27% less energy to heat and cool than a 6-star home. In a cold climate like Canberra's, that difference is significant.

Getting to 7 stars changes how we design and price a home. Double glazing is now essentially mandatory - you can't reliably hit 7 stars with single-glazed windows in Climate Zone 7. That's had a real impact on costs. Across the industry, we're seeing window costs add $50,000 to $60,000 more per home compared to a few years ago. I won't pretend that's trivial. It's a real cost increase, and homeowners deserve to know it upfront.

That said, design decisions can reduce how much compliance costs you. A home that's well-oriented - with living areas facing north to capture winter sun - naturally performs better thermally. Good design can reduce compliance costs by $1,000 to $2,000. That's not pocket change, and it's why I always push clients to think about orientation early, before the design is locked in. By the time my site manager and project coordinator are managing day-to-day delivery, those design decisions are already made. They need to be made at the start.

What About Renovations and Extensions?

This is where things get more complicated, and where I see the most confusion.

If you're adding an attached extension to an existing home, the existing home may also be required to meet higher energy standards - not just the new extension. This is assessed through what's called a Deemed to Satisfy (DTS) report. The DTS pathway lets a building certifier confirm that the existing structure meets the relevant energy provisions of the NCC, or identifies what upgrades are needed to comply.

Not every renovation triggers this. A kitchen fit-out or bathroom replacement generally won't. But if you're adding a bedroom wing, a significant living extension, or anything that's structurally attached and expands the conditioned floor area, you need to get proper advice before you start.

A full EER assessment typically costs around $480 plus GST. That's money well spent before you commit to a design, because finding out mid-project that your 1970s brick home in O'Connor needs wall insulation retrofitting and new windows to comply is a much more expensive problem.

Suburbs like Ainslie, Griffith, and O'Connor have a lot of housing stock from the 1960s and 70s. Many of those homes rate between 1 and 3 stars. They were built with single-brick walls, no insulation, and single-glazed timber windows. They're draughty. There's a well-known benchmark in the building industry that draughts in a typical older Canberra home add up to the equivalent of a 40-centimetre square window left open all year. Every heating dollar you spend is partly heating the street.

If you own one of those homes and you're planning a significant extension, talk to your builder and an energy assessor early. The scope of what you might need to upgrade isn't always predictable from the outside.

Practical Ways to Improve Your Home's Energy Efficiency

Whether you're building new or renovating, these are the areas that move the needle on energy efficiency in Canberra:

Orientation. North-facing living areas, kitchens, and main bedrooms capture passive solar heat in winter and can be shaded by eaves in summer. It costs nothing extra if it's designed in from the start. It can cost a lot to compensate for if it's done wrong.

Insulation. Ceiling insulation has the biggest impact and is the most cost-effective upgrade. Wall insulation matters too, especially in new builds. Underfloor insulation is worth considering in elevated homes or those over a cold sub-floor void.

Windows and glazing. Double glazing is non-negotiable for new builds now, and it makes a real difference in existing homes too. Look for a good Window Energy Rating Scheme (WERS) rating, not just double glazing as a marketing term. The gap, the gas, and the frame material all affect performance.

Draught sealing. One of the cheapest, most impactful things you can do in an older home. Seal gaps around doors, windows, exhaust fans, and roof penetrations. In existing homes, this is where a lot of cheap wins are found.

Eaves and shading. Properly designed eaves shade north-facing windows in summer but let winter sun in. This is basic passive solar design, but it's often compromised when designs are rushed or clients want maximum glass.

The Cost vs Benefit Reality

A 7-star home saves the average household up to $600 per year on energy bills compared to a lower-rated home. Over 10 years, that's $6,000. Over 20 years, it's $12,000 - and that's before accounting for rising energy prices.

Is the extra upfront cost worth it? In most cases, yes - particularly in Canberra, where the heating load is high and the payback period on things like double glazing is shorter than in warmer climates. But I won't oversell it. The payback on some premium upgrades is long. My job is to help clients spend money where it actually makes a difference, not where it sounds impressive on a brochure.

The rating system is also imperfect. A home's energy performance depends on how people live in it - whether they open windows, how they use heating and cooling, and whether they follow through with things like draught sealing after they move in. A 7-star design that's poorly detailed and draughty will underperform a well-built 6.5-star home. Construction quality matters as much as the rating.

Frequently Asked Questions

Does every renovation in Canberra require an EER assessment?

Not every renovation. Generally, if you're adding a new attached extension that increases the conditioned floor area, energy compliance is triggered. Cosmetic works - painting, new flooring, kitchen updates - don't require a new assessment. If you're unsure, ask your builder or certifier before you start planning. An EER assessment costs around $480 plus GST and is money well spent early.

My home in Griffith was built in the 1960s and rates 2 stars. Do I have to upgrade it?

Only if you undertake significant renovation or extension work. Simply owning or living in a low-rated home doesn't require you to upgrade. However, if you're planning an attached extension, the DTS pathway may require the existing home to meet updated energy provisions. The scope of required upgrades depends on the specific work and how your certifier assesses compliance.

What's the difference between EER and NatHERS?

NatHERS (Nationwide House Energy Rating Scheme) is the national framework that underpins the star rating system. An EER is the ACT-specific term for the star rating produced by a NatHERS assessment. They're closely related - the star rating you see on an ACT property listing is generated using NatHERS-accredited software such as AccuRate or FirstRate5.

Will double glazing alone get my renovation to 7 stars?

Not on its own. A 7-star rating depends on the combined performance of the whole building envelope - walls, roof, floor, windows, and draught control. Double glazing is a major contributor in Climate Zone 7, but it works alongside insulation, orientation, and shading. An energy assessor can model the home and identify the most cost-effective combination of measures to reach the required rating.

How do I find an accredited EER assessor in Canberra?

Assessors must be accredited under NatHERS. You can search the register at the NatHERS website. Your builder should also be able to refer you to assessors they've worked with - it's worth choosing someone with experience in Canberra's cold climate conditions and familiarity with the ACT's specific disclosure and compliance requirements.

Talk to Rentoule Projects

If you're planning a new home or a major renovation in Canberra, energy efficiency needs to be part of the conversation from day one - not a compliance box you tick at the end.

At Rentoule Projects, we work with experienced energy assessors and design for Canberra's climate from the ground up. We'll be honest with you about what's required, what's worth spending money on, and what the rating will actually mean for your comfort and your bills.

Contact Rentoule Projects to talk through your project.