BASIX & NatHERS News

The last BASIX increased targets came into effect in NSW in October 2023, where our sustainability targets increased:

 

• Building shell performance level equivalent to a 7 Star NatHERS rated dwelling (was previously around 5.5 stars)

• A reduction in greenhouse gas emissions from operational energy use: Stricter targets for Energy usage including more efficient water heating systems, efficient space conditioning systems for heating and cooling, and lighting (eg. Energy efficient LED lighting throughout). Most dwellings will require Photo Voltaics (eg. Solar panels) to gain a passing result

• No increases to water targets at this stage

• The addition of Embodied Energy targets: The materials calculator reviews the proposed building materials and their quantities to ensure the embodied carbon usage is not too high upfront in the building stage.

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Whilst there will be additional capital outlays required with building, there are benefits of the increased BASIX Targets:

 

• Energy savings: reduced costs in electricity and gas consumption saving money in the long run. Operational costs of the home will are less as dwellings will are more thermally comfortable due to higher standards of passive design, allowing the home to be naturally warmer in winter and cooler in summer

• Heating and cooling spaces in buildings is one of the most intensive usages of power in the world. With the ever-increasing population, increased BASIX targets assist with providing less strain on the grid at any time as a result of less demand for power usage

• Health benefits from reduced pollution from energy and gas generation, and for creating less Green House Gas emissions in the production of the materials being used for construction

• It is anticipated that the additional upfront cost outlay will be passed forward to property buyers in the form of a slight increase in house prices

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Designing your home to achieve a 7 Star NatHERS Rating:

 

Under NCC 2022, NatHERS Star ratings increased to a minimum target of 7 Stars. You will also need to meet a heating score and cooling score applicable to your climate zone. It is important to know that your Energy Rater won’t always be able to get you to 7 Stars with simple insulation and glazing upgrades. Design changes may be required, and here are some of the aspects that will need to be taken into consideration:

 

• Orientation and shading from trees and surrounding buildings is important. If you have entire sides of your home open without shading from surrounding obstructions, this will result in a ‘hotter’ home. Conversely, should your home be overshadowed by neighbouring buildings on all sides, the home will be too cold. You will need to design your eaves and shading devices accordingly. Keeping living areas facing north, but with adequate shading, will be critical to keep your home cool in summer and warm in winter.

 

• Roof and wall colours: deciding on colours upfront will assist so that your NatHERS Assessor does not have to use the ‘Default’ colours which are assumed to be worst case scenario. Sydney is considered to be a warm climate, and it is ideal to use lighter colours as they will absorb less sun (heat) than darker colours. Opting for light colours, and only up to a maximum of medium (no dark) will help. Conversely, if you are building in a cooler location such as a place where it snows or has regular temperatures below zero degrees Celsius, you would benefit from a darker coloured roof to attract the sun and keep your house warmer.

 

• Glazing reductions, solar orientation and cross-flow ventilation: The walls and roof of your home are well insulated to prevent hot and cold air from entering your home, or to at least slow it down a lot. When you install a window, you are placing a ‘hole’ in that insulated wall. Windows and glass doors can be a major source of heat gain in summer and heat loss in winter. Whilst the light from the sun can make a space brighter during the day to reduce the need for artificial lighting, the drawbacks are substantial. The house becomes uncomfortable and the requirement for air conditioning then increases. Reducing the amount of glazing by opting for smaller windows, and replacing fixed windows with windows that open in a hot area of the home will help. Also placing windows opposite each other on other sides of the home will allow for cross ventilation. This will reduce the need for low-e glazing, double glazing, and in some instances low-e double glazing. Window selection, sizes and locations will affect the star rating, are you open to testing different windows (eg. Awning as opposed to sliding, or fixed, etc.)? As your Assessor, we can test this for you and let you know if any improvements can be made. The glass to floor area ratio of Living area rooms should be decreased as these areas are considered to be using the most energy.

 

• Passive shading: Northern sides of your home benefit most from fixed shading such as eaves and awnings. Adjustable shading that is vertical, such as external blinds or screens, are often recommended for the eastern and western sides of your home. This is because the sun rises and sets at lower angles in the sky on the east and west, and horizontal shading from eaves and awnings will generally not keep the sun out. Shade cloth, external blinds and louvres, and deciduous planting can also be used to provide self-adjusting seasonal shading.

 

• Increased thermal mass: Concrete slab on ground absorbs heat and cold from the surrounding air and releases it slowly into the home, whereas a suspended timber floor will release the heat and cold into the home nearly immediately. Therefore concrete creates a more comfortable home. Covering the slab with carpet will make it warmer than covering it with tiles in summer, so taking into consideration your floor coverings is essential too. Brick construction provides more insulation than lightweight framed construction, and will work better to keep heat in or out.

 

• Shape of the home: Think about the centre point of your home, if you had to mark a dot in right in the middle of your home and assess how quickly the heat and cold could get through the walls to that point. A square/cube shape will allow for heat and cold to pass over each wall and make it’s way into the centre quite evenly and more slowly. A long skinny rectangular home will allow the heat and cold to make it’s way into the home and reach that centre point pretty quickly, specifically through the ‘skinny’ part. Same goes for a two storey home that is not exactly cubic, and has split levels and more external surface area. We ideally want square shaped designs with the least amount of surface area, and that top floor of the home to be constructed directly above the ground level with no suspended floor, or exposed roof on the ground floor. This allows for the least amount of surface area to be exposed and will result in a better performing home.

 

• Insulation between conditioned spaces and unconditioned spaces: Laundry’s and Bathrooms that have a window or door opening to the external façade are considered unconditioned. So are Garage spaces. These areas are considered to have more fluctuating temperatures that reflect the outside environment more than other rooms in the house, and are likely not airconditioned. The Garage will likely have a simple non-insulated metal door. The Laundry will likely have a washing machine, and possibly dryer working, with a window or door open to reduce condensation. By placing insulation to the internal walls of these areas will assist with blocking the temperature changes from these hot and cold spaces into the rest of the home. In the event of a two storey home, placing insulation into the Garage ceiling where habitable rooms are above will assist the rooms above to stay more comfortable.

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Here is a link to the Nationwide House Energy Rating Scheme (NatHERS) Administrator where you can view and download free energy-efficient house designs: https://www.nathers.gov.au/owners-and-builders/7-star-house-plans

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To read more about the NSW Planning Department's increase to BASIX Standards, visit: https://pp.planningportal.nsw.gov.au/BASIX-standards

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