The NatHERS Report Mistake That Could Cost You Thousands

Choosing the right windows and doors can be a daunting task, especially if you're new to the building or renovation process.

Despite what we often hear about reducing "red tape" within the construction industry, the reality is that there are now more compliance requirements than ever before. Gone are the days of simply walking into a window and door supplier with a list of sizes and a colour preference. Today, you'll also need to bring along your energy assessment report—commonly known as a NatHERS report.

And that's often where the headaches begin.

Over the years, as energy efficiency requirements have become more heavily enforced, I've noticed a recurring issue. More than 50% of the clients I speak with have never been asked what frame type or, more importantly, what glass type they want included in their energy report.

This is a major red flag.

Why? Because the selections entered into your NatHERS assessment directly impact what products can be used in your home.

Unlike many other states, Tasmania chose not to adopt the National Construction Code's 7-Star NatHERS requirement for new dwellings and has retained the 6-Star standard. While this may sound like a minor difference, it can have a significant impact on the type of windows and doors required for your project—and ultimately, your budget.

In many cases, a Tasmanian home can achieve a 6-Star rating using standard aluminium window and door systems combined with standard glazing options. However, because the 7-Star requirement has been so heavily promoted across the country and even falsely advertised on NatHERS very own website, we're increasingly seeing energy reports prepared using 7-Star assumptions or performance targets.

When this happens, window and door suppliers are often forced to quote higher-performing products to satisfy the report. This can include thermally broken aluminium frames or specialised Low E glazing that may not have been necessary if the assessment had been completed using Tasmania's current requirements. While these products certainly have their place and can deliver excellent performance outcomes, they also come with a higher price tag.

For homeowners, this can result in unexpected costs, budget blowouts, or difficult decisions later in the project. In some cases, we've even seen clients delay or redesign parts of their build after discovering the window package is substantially more expensive than originally anticipated. That's why it's so important to understand what assumptions have been used in your NatHERS assessment before obtaining quotations.

"Talk to your designer or energy assessor early about your preferred glazing options and budget. A simple conversation now could save you time, money, and frustration later."

A simple conversation with your designer, energy assessor, or window supplier early in the process can help ensure the report aligns with your project's goals, budget, and the requirements applicable in Tasmania. After all, the best energy report isn't necessarily the one that achieves the highest star rating—it's the one that balances compliance, performance, practicality, and cost for your individual project.

Questions to ask

✅ What glass type is included?

✅ What frame type is included?

✅ Is the assessment based on 6 or 7 Stars?

✅ Can I change glazing later?

✅ How will changes affect my rating?

At GP Glass, we're always happy to provide energy performance data for our window and door systems to your designer or energy assessor. That way, you can focus on the really important decisions—like choosing colours, finishes, and all the details that bring your dream home to life.