AUTHOR: Clive BlanchardTransforming Houses into Energy-Saving Gems for Builders, Architects, and Homeowners at low cost. Archives
October 2025
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A Practical Guide for Homeowners and ArchitectsExecutive SummaryThis guide compares two leading approaches to residential energy efficiency in Adelaide and the Adelaide Hills: Australia’s Nationwide House Energy Rating Scheme (NatHERS) and the international Passive House standard. Both aim to create comfortable, energy-efficient homes, but differ in philosophy, requirements, and outcomes. Most people focus on the visible differences, but to know which is right for you, we need to look deeper.  NatHERSis Australia’s mainstream system, rating homes from 0 to 10 stars based on design features like orientation, insulation, and shading. It is primarily a design-based assessment, widely used for building approvals, and focuses on cost-effective compliance with the National Construction Code. However, it does not require post-construction testing, so actual performance may vary depending on build quality. To find out more how I can help, see New home, energy efficiency consultation - YOUR LOW ENERGY HOME Passive House (Passivhaus)originating from Germany, is a rigorous, performance-based standard. It requires strict limits on energy use, airtightness, and indoor comfort, verified through third-party testing. Passive House homes feature superior insulation, airtight construction, and mechanical ventilation with heat recovery, resulting in exceptional comfort, low energy bills, and healthy indoor air quality. This approach involves higher upfront costs and specialized skills but delivers long-term value and resilience. To find out more how I can help, see Passive House Design Services - YOUR LOW ENERGY HOME In Adelaide’s Mediterranean climate (warm temperate)NatHERS offers a practical, familiar route for compliance and moderate cost, while Passive House provides best-in-class comfort and energy savings, especially for those prioritizing health and long-term performance. A hybrid approach—either using NatHERS for compliance and incorporating Passive House principles or alternatively designing to Passive House, but operating like a NatHERS home—can help achieve optimal results. Conclusion:Both standards support Australia’s move toward healthier, more efficient homes. The right choice depends on your priorities: NatHERS for ease and affordability, Passive House for superior comfort and performance. Combining elements of both can deliver the best outcomes for Adelaide’s unique climate and evolving housing needs. If you are thinking of building or renovating, contact me for a free discussion of your needs. For a deeper dive, keep reading. A detailed comparisonIntroductionAre you planning a new home or looking to elevate your building designs in Adelaide? If so, you’ve likely come across sustainability buzzwords like NatHERS and Passive House. But what do they actually mean for your comfort, costs, or project outcomes? This blog breaks down these two approaches—Australia’s NatHERS rating and the international Passive House standard—to help both homeowners and architects make informed decisions in Adelaide and the Adelaide Hills’s unique climates. Refer Where is my homes energy going? - YOUR LOW ENERGY HOME for why you should focus on information and consultants targeting your local climate. Often when people look at Passive House they focus on the typical physical differences, but to understand what is best for you, you should look at the philosophical differences (see key differences below). Understanding NatHERS: Australia’s Home Energy Rating SystemThe Nationwide House Energy Rating Scheme (NatHERS) is an Australian government system that assesses how well a home’s design keeps you comfortable year-round with minimal heating or cooling. You’ll see homes rated between 0 and 10 stars based on factors like orientation, insulation, glazing, and shading—think of it as a “first pass” on energy efficiency.
What’s Passive House?Passive House (or Passivhaus) comes from Germany but is growing in Australia. It’s a global gold standard for energy-efficient, ultra-comfortable homes. Unlike NatHERS, Passive House is performance-based: you must meet strict targets not just in the design, but also in the way the building is actually built and tested.
Key Differences at a GlanceOrigin NatHERS Australia Passive House Germany (International) Philosophy NatHERS Follows the traditional Australian approach of only heating and cooling rooms when you use them. For a given level of comfort, this will use less energy in a Mediterranean climate. Passive House Follows the northern European approach of keeping all rooms comfortable all the time. This is because if it is -20C outside, you can’t afford to have the bathroom freezing, apart from the comfort, you risk your water pipes freezing and bursting. Consequences of the philosophy NatHERS Lower cost building as not all rooms need to be insulated to the same level as a Passive House. Passive House Higher cost building, but a significantly better level of comfort. Rating NatHERS 0–10 stars (modelling only) Passive House Pass/Fail, strict targets and testing, although there are different levels of Passive House Focus NatHERS Thermal performance on paper Passive House Verified performance: energy, airtightness, comfort, air quality Testing NatHERS No onsite testing required Passive House Blower door airtightness test mandatory Ventilation NatHERS Natural ventilation only. (although the building code addresses short term mechanical ventilation in some rooms) Passive House Mechanical ventilation with heat recovery (MVHR) standard Adelaide’s Climate: Why Context MattersWith its hot, dry summers and cool, wet winters, Adelaide’s Mediterranean climate presents unique challenges for home comfort and efficiency. The difficulty of achieving comfort in Adelaide is illustrated by the fact that South Australia was the first state to reach 90% of homes with some form of air conditioning, in spite of being the poorest mainland state. It should also be noted that in most homes winter heating dominates energy use, rather than summer cooling. NatHERS in AdelaideNatHERS software is adapted to Adelaide’s conditions, encouraging smart passive design—like optimising your orientation, shading, and insulation. This approach is effective for compliance, cost control, and familiar to local builders. Keep in mind, though, that the final result depends on quality construction, as there’s no mandatory testing once the home is built.
Passive House in AdelaideFor those wanting to push the envelope—whether you’re an architect, developer, or adventurous homeowner—Passive House delivers year-round comfort and consistency. Superior insulation, airtightness, and controlled ventilation mean homes stay cool in summer and warm in winter, with minimal energy bills and excellent air quality.
So, Which Approach is Right for You?The bottom line:
Conclusion: Blending Strengths for Better HomesBoth NatHERS and Passive House support Australia’s transition to healthier, more efficient homes. In Adelaide, where climate extremes are the norm, using NatHERS for compliance and drawing on Passive House principles for design and construction can help you achieve the best of both worlds. Alternatively, designing the fabric to Passive house standards, but heating and cooling in the way NatHERS assumes, can also achieve a great solution.
Whether you’re a homeowner navigating your build or an architect seeking to stand out, understanding the differences between these standards will empower you to make smarter, future-proof choices for Adelaide’s evolving built environment. If you are thinking of building or renovating, contact me for a free discussion of your needs.
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Is it time to rethink windows?1/4/2025 Windows are an essential part of our homes and buildings, providing natural light, ventilation, and a connection to the outside world. However, they also come with costs that we often overlook. In this post, we'll explore the historical background, cost of windows in terms of energy flows, the price of high-performance windows, the extra cost of complying with energy efficiency requirements for large windows, why we have windows and glazed doors in the first place and what we can do to keep the benefits but minimise the costs. Why We Have Windows and Glazed DoorsDespite the costs associated with windows, they remain a crucial element of building design. Windows and glazed doors provide natural light, which can improve mood. They also offer ventilation, helping to maintain indoor air quality. Additionally, windows can connect us to the outside world, providing views and a sense of openness and oneness with nature. These benefits make windows an indispensable part of our homes and buildings, even as we work to improve their energy efficiency. Historical backgroundIf you consider homes built in Australia built before the fifties, they had small windows because the predominant form of heating was open wood fires. Because they are not an effective form of heat and insulation was rare, windows were as small as possible to reduce heat loss so the rooms could be heated to a moderately comfortable temperature. The small windows also minimised summer heat gain. Because house comfort levels were so poor, most people were aware of the comfort cost of windows. Frank Lloyd Wright (1867-1959) an American Architect is generally attributed with developing the concept of large glass windows connecting to the outside which has been embraced in Australia. The early Australian exponent of this concept was Robin Boyd (1919-1971). However, you need to recognise Frank Lloyd Wright was designing for the wealthy who could afford the high heating costs of the buildings, and he experimented with early air conditioning systems to try and keep them cool. Although he later embraced the use of shading to maximise winter warmth and minimise summer heat build-up, these techniques are insufficient in South Australia to achieve comfort all the time. It should be noted that even Frank Lloyd Wright implicitly recognised his homes didn’t give year-round comfort and he later lived in Chicago in the summer, and Arizona in the winter. During the 1970’s builders in Australia realised that the construction cost of a square meter of brick veneer wall and a square meter of single glazed aluminium sliding windows was the same. This meant a show home could be built with large windows facing a landscaped garden to give the wow factor that closed the sale. Because the show home could have air conditioning and people were less likely to go out on an extremely hot or cold day (cars didn’t have air conditioning) people didn’t notice the problems until after the house was built. The problems with excessive windows include:
Because expectations in Australia have moved to large, often floor to ceiling windows, to achieve the star rating can be expensive. We need to minimise these negatives while still retaining the positives of light and the connection to the outside. The Cost of Energy Flows Through WindowsWindows can be a significant source of energy loss in a building (up to 40% of energy loss in existing homes that I energy audit). During the winter, heat escapes through windows, leading to higher heating costs. In the summer, windows let in unwanted heat, increasing the need for air conditioning. It's essential to consider these energy flows when designing or renovating a building to ensure energy efficiency. You also need to spend money on curtains or blinds, even in a 7-star home, so avoiding excessive windows also reduces this cost. The Extra Cost of Complying with Energy Efficiency RequirementsLarge windows can be a beautiful feature in a building, providing ample natural light and stunning views. However, they also come with additional costs to comply with energy efficiency requirements. High-performance windows are designed to minimize energy loss and improve a building's overall energy efficiency. These windows often feature multiple panes of glass, low-emissivity (Low-E) coatings, and Argon gas between the panes to reduce heat transfer. They also have high performance window frames. While high-performance windows are more expensive upfront, they lead to significant energy savings over time. In fact, if you have a lot of glass, you won’t be able to achieve a 7-star rating without high performance glass. This is the main driver of increased costs for 7-star homes. However careful design can minimise this cost. The Australian Glass Window Association research has shown the average premium is $4,300, not the $40,000 plus premium touted by the Housing Industry Association (although this latter figure is possible, if you don’t consider windows, orientation and building form carefully). However, it is possible to achieve the benefits of windows with substantially smaller windows that are common today, but you need to start considering these ideas when considering the block and house concept, not when you have detailed designs as the costs will already be locked in. See How early design decisions impact the cost of achieving energy efficiency in homes - YOUR LOW ENERGY HOME and Optimal House Orientation in Adelaide: More Than Just Facing North - YOUR LOW ENERGY HOME A future knowledge base post will address how we can achieve this and achieve a lovely home at an affordable cost. In the meantime, contact us to get started on the energy efficiency planning for your home as early as possible. ConclusionWhile windows offer significant benefits, they come with costs in terms of energy flows, comfort, window treatments and the cost of compliance with energy efficiency requirements. By careful design we can achieve the benefits with smaller windows than is common today, minimising the cost of high-performance windows, and we can enjoy the advantages of windows while minimizing their impact on our hip pocket.
Contact us to get started on the energy efficiency planning for your home as early as possible.
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Early design decisions (even as early as choosing the block and associated building shape) have a significant and often overwhelming impact on a new home or renovation final cost, particularly with respect to meeting energy efficiency requirements. The majority of the cost is locked in during the initial conceptual stages, as correcting early design decisions is significantly more expensive due to the ripple effects on other decisions. Key points about the impact of early design choices on building cost to meet energy efficiency requirements: Showing typical relative costs to achieve a 7-star energy efficiency rating at different stages of the design process. The earlier in the process you introduce an energy efficiency advisor, the lower the eventual cost to achieve the required rating.
Benefits of careful early design consideration:
Strategies to manage early design cost implications:
To find out how I can help you cost effectively achieve a 7-star energy rating go to Architect and Builder Services. or Contact us
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Understanding the Best Orientation for a HomeWhen it comes to building a house in Adelaide, the conventional wisdom suggests that facing a home north is the ideal orientation. However, this is not always the case. The shape of a block and the type of home you intend to build are crucial factors that influence the best orientation for a specific situation. By choosing the right orientation for a home, you can reduce costs and enhance comfort. Factors Influencing House OrientationThe Importance of the Block ShapeThe shape and size of a block significantly impact the optimal orientation of a house. For instance, if you have a deep and narrow block, you may be forced to use a different home layout than if you have a wide fronted block. The wider the frontage, the more flexibility you have in designing a home with either large windows facing the street or a patio at the back. However wider frontages tend to be more expensive, regardless of whether it is an infill development or a greenfield site. The Type of Home You Want to BuildThe design and layout of a home also play a pivotal role in determining the best orientation. If your house design includes large windows facing the street, a north-facing block may be optimal as it allows for passive solar heating and natural light. However, if you prefer large windows overlooking a backyard patio, a south-facing block might be more suitable. If the block faces south the main windows can face north and open onto the back yard giving a very pleasant aspect. Window Orientation Over Block OrientationWhile the block's orientation is important, it is through how it influences the shape of a house and orientation of the windows and is not inherently important by itself. The placement and size of the windows will determine how much natural light and heat a home receives. For example, if a home has large windows on the front façade and you are building on a wide-fronted block, a north-facing block will maximize sunlight. On the other hand, if the main living areas have large windows facing the backyard, a south-facing block will provide a more comfortable living environment. Deep Blocks and Side WindowsNarrow, but deep blocks present a different set of challenges and opportunities. If the block is deep, you may need to place more windows on the sides of the house to ensure adequate natural light and ventilation. In this case, an east or west-facing block may be the best option. The side windows should ideally primarily face north and give you an opportunity to have a northern courtyard which will be pleasant in summer and winter. Challenging Traditional NotionsTraditionally, west-facing blocks are considered the least desirable due to the intense heat from the afternoon sun. However, this orientation can be advantageous if the front façade of your home is largely a garage. The garage can act as a buffer, protecting the living areas from the harshest sunlight and reducing cooling costs. The garage most importantly reduces the area of windows facing west and hence reduces the building cost required to keep the summer heat out. Maximizing Comfort and EfficiencyBy carefully considering the orientation of the house and windows, you can maximize comfort and efficiency. A well-oriented home will take advantage of natural light, reduce reliance on artificial heating and cooling and create a more pleasant living environment. Reducing Construction CostsChoosing the right orientation can also help reduce construction costs. Properly oriented homes require lower cost windows and window treatments, costing less to construct a 7-star home This can lead to significant savings during the construction process and greater comfort and more light in the home. ConclusionIn conclusion, while north-facing homes are often idealized, the best orientation for your house in Adelaide is not a one-size-fits-all solution. It depends on the shape of your block, the type of home you want to build, and the placement of your windows. By thoughtfully considering these factors, you can create a home that is comfortable, efficient, and cost-effective. Whether you have a wide-fronted block, a deep block, or a narrow block, there is an optimal orientation that will suit your needs and preferences. Embrace the flexibility and design a home that truly works for you and your lifestyle.
To find out how I can help you cost effectively achieve a 7-star energy rating go to Architect and Builder Services. or Contact us
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Free White Paper12/10/2023 Leveraging Energy Advisors for South Australian Builders: A Strategic Approach to Meeting 7-Star Home RequirementsGet your free white paper and ensure you are one of the builders or architects who are ahead of the game and come out of the changes more profitable, not less profitable.
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Building Green can be affordable7/10/2023
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What we help with: Our goal is to help people make the most cost-effective decisions to reduce greenhouse gas emissions. We will work with you to achieve your goals at the level of expenditure which is comfortable for you. This can be achieved while increasing comfort and amenity. |
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We acknowledge the Traditional Owners of the Land on which we live and work and recognise their continued connection to Country. We pay our respect to their elders, past and present and extend that respect to all Aboriginal and Torres Strait Islander people.