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7 Star BASIX & NatHERS Requirements, What Do They Mean For The Average House



It has been almost 6 months since NSW adopted the NCC 2022 energy efficiency requirements. How has this affected the requirements for most dwellings? And what is in store for the other states & territories as these new requirementscome into effect?


Introduction

The 7 star BASIX & NatHERS requirements represent a significant shift in the building and construction industry. These requirements, which focus on sustainable building and energy efficiency, are designed to reduce the environmental impact of residential buildings. They also aim to improve the comfort and affordability of homes by reducing the need for artificial heating and cooling.


These new BASIX & NatHERS requirements are helping to keep your house cooler during the summer and warmer during the winter with the goal of not needing the heater or air conditioner as often. The BASIX team has been quoted saying that due to these changes, home owners could be saving as much as $980 a year on energy bills. This is equivilant to around 500,000 trees being planted. These changes are all heading in the direction of net zero homes meeting the goal of by the year 2050. But what does this mean for the average home owner? Let us see.



What the Updates Mean

The new requirements introduce higher thermal performance standards for residential buildings. This means that homes will need to be better insulated and more airtight to prevent heat loss in winter and heat gain in summer. The requirements also include the calculation and recording of embodied emissions of building materials. But how does this translate to new building requirements?


Single storey dwellings:

On average, single storey dwellings with sufficient eave shading can still achieve low NatHERS requirements. In fact, with this, along with a good north orientation and low glazing to floor area ratios, a dwelling can pass with low insulation requirements and single clear windows. Very similar to the previous requirements. However, if a good orientation is not possible, the windows aren't sufficiently shaded or there is a high glazing to floor area, the insulation will quickly max out & windows will likely need a minimum of low-e to pass.


Double storey dwellings:

A two storey dwelling can be significantly more difficult to pass both NatHERS & BASIX. This is now because, in most cases, the ground floor windows are not shaded, causing a lot of heat to enter the house. How can we find a work around to this? The cheapest and most effective choice is to shade the ground floor windows. This can be down by using outdoor venetians, roller shutters or window shade awnings.


How to Pass the New NatHERS & BASIX Requirements

Passing the new requirements involves good design and orientation of the building. A building that is well-designed and well-oriented can take advantage of passive solar heating in winter, and natural cooling in summer. A NatHERS assessor can provide valuable input during the design process, helping to ensure that the building meets the new requirements. Improving energy efficiency can be achieved by using double glazing or low-e coatings on windows, and including more internal doors in the design. However, increasing window glazing performance should be considered the last resort when it comes to finding solutions for NatHERS. There are several ways to lower glazing requirements, let us look at some alternatives.


Foil Boards. One option is to use R2.0 foil boards to external walls in addition to the R2.5 batts. This can significantly reduce heat transfer through the walls, helping to maintain a comfortable indoor temperature. This option can be used on almost all walls from brick veneer to cladding. Although this requires the dwelling to essentially be cladded an extra time, it can make quite a difference in lowering glazing requirements.


Hebel Power Flooring. Another option is to use Hebel power flooring to the first floor framed floor. This is a type of flooring that has excellent thermal insulation properties, helping to reduce heat loss through the floor. It is a 75mm panel, similar to what is used on in hebel veneer construction, which can give the push that the dwelling needs to get over the line.

Ceiling Fans. Ceiling fans provide a huge advantage to lowering glazing in NatHERS. Opting for ceiling fans in living and/or bedrooms can provide amazing benefits. To give an example, I recently completed a NatHERS certificate for a set of dual occupancies in eastern Sydney. These dwellings were designed without eaves and were struggling to pass. They didn't want window shade awnings as these affect the appearance of each dwelling. At first, they also didn't want ceiling fans, which really only left them with the option of higher glazing requirements, which was double glazed, argon filled low-e. Once they realised the cost of these windows, they eagerly worked with myself to find a reasonable solution. We decided to go down the route of using ceiling fans in each room, with some rooms that were really struggling with cooling using 2100mm ceiling fans. In the end, we were able to pass with only a 6.38 laminate film on the windows which kept the costs low. So, ceiling fans can definitely be a great option!

Slab Insulation. Under slab insulation is another option which can provide great benefit, even though most builders tend to shy away from it. By using a reflective void slab design or by adding EPS sheets under the slab, you can make quite a difference in your NatHERS star rating.

uPVC or Timber Windows. I cannot stress how much of a benefit these windows have on top of regular aluminium windows. uPVC is a cheaper window alternative that perform better than aluminium framed windows and are low maintenance. Using uPVC windows can make a huge difference in the results in the dwelling. However, they are known for not being as durable as aluminium but, they can be recycled and reused. On the other hand, timber windows are another great option as they perform better than aluminium windows & can give the dwelling a timeless style. Although they require a bit of work to maintain, they really make up for it in their design.


Conclusion

The new 7 star BASIX & NatHERS requirements are a significant step towards more sustainable and energy-efficient residential buildings. We don't need to be afraid of the extra costs involved if we plan from the start to design a more efficient building and use some more unconventional requirements to get over the line. By understanding and embracing these changes, builders and homeowners can contribute to a more sustainable future. These changes represent an opportunity to build homes that are not only more comfortable and affordable, but also kinder to our planet.


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