Buying an existing home

Key points

  • If you are buying an existing home, knowing what to look for can help to ensure your home will be comfortable, cost effective to run and sustainable.
  • Different features will be important in different climates. Find out your climate zone, and do some preliminary research to understand how to identify a home that suits your climate.
  • It is rare that you find a home that has everything you want. Do some research to find out what changes can be made easily through renovations, and what will be difficult or expensive to do.
  • When you inspect homes, thermal comfort should be a key consideration. Also assess the risk of structural problems, damp, fire and termites.
  • Expert advice can be invaluable. Get a design or building consultant to look at your shortlist of homes to see which will perform best and estimate the cost of renovations.

Understanding buying an existing home

Buying an existing home simply means that you buy a home that has already been built. The home might be a freestanding house on a block of land, a townhouse, or an apartment.

Buying an existing home has some advantages. You can see exactly what you are getting, and you can visit the home several times and see how it performs during different times of the day.

If you buy a home that has been built for a few years, any potential problems should have had a chance to show up. Bear in mind that homes built before 2006 will not have been required to meet energy performance targets of the National Construction Code (NCC). The NCC sets the minimum necessary requirements for safety and health, amenity and accessibility, and sustainability in the design, construction, performance, and liveability of new buildings throughout Australia.

Buying an existing home also means that various aspects of the design and fittings may not be just as you would like. You will need to decide whether the home can be cost-effectively renovated to suit your lifestyle and to be more comfortable and sustainable.

Preliminary research

Careful research and assessment improves the likelihood that your new home will be comfortable, cost effective to run and maintain, and hold its value into the future. For a more detailed description of this stage refer to Preliminary research. The advice below provides some specific tips for buying an existing home.

Market and financial research

Know your budget, and choose a suburb or locality that suits both your lifestyle and budget. Remember that a more expensive home with good sustainability features will save money each year, with lower energy and water costs than a poorly designed but cheaper home.

Also be aware that some banks offer lower interest rates or other benefits for homes and renovations that achieve sustainable outcomes.

Sustainability research

Start your research by identifying your climate zone and developing a good understanding of how to choose a home that will work with, rather than against, your climate.

Make achieving thermal comfort with the lowest ongoing costs central to your decision making at every stage. Draw up a list of ‘must haves’ and ‘must avoids’, based on your climate zone. For more information refer to Preliminary research.

Also, make sure you are familiar with the options for renovation, including those that might be achieved easily, or those that might be difficult or more expensive. Doing your homework on the likely cost and impact of modifications, upgrades and additions will help you to identify houses that can be more easily improved.

The thermal mass of the concrete floor in this modern home and its reverse brick veneer walls help regulate internal temperatures. Ceiling fans and smaller windows on the south and east sides assist air circulation and cross ventilation.

Look for houses with high levels of thermal comfort

Photo: Warren Reed (© Beaumont Building Design)

Inspecting homes

Inspecting a home allows you to see the space, layout, and structure. However, expensive hidden traps and inexpensive opportunities are often missed by inexperienced buyers.


Sometimes an apparent bargain can be difficult or very costly to retrofit for sustainable performance. Conversely, a seemingly expensive home might be simply and cost-effectively upgraded.

A thorough pre-purchase evaluation is a critical step in choosing an existing home to buy and potentially renovate. Consider engaging an experienced, professional consultant (designer or builder) to identify the home’s potential, expose hidden problems, and balance the cost of rectification or renovation against purchase price. This advice can more than pay for itself.

Thermal comfort

Where a Nationwide House Energy Rating Scheme (NatHERS) star rating is available for the homes you are looking at, the higher the rating is the better. It may be also be worth considering if there is the ability to improve homes with lower star ratings. The National Construction Code has required that homes built since 2006 have a minimum NatHERS star rating of 5, homes built since 2010 must have a minimum rating of 6, and homes built since October 2023 must have a minimum rating of 7 (or thermal performance equivalent to 7 stars if using other compliance pathways) - though these requirements may vary depending on your state and territory. Seek advice from an accredited building energy assessor to check the NatHERS star rating.

Check for features that will deliver thermal comfort for your climate zone. In summary:

  • Designs for Climate zones 1 (Hot humid summer, warm winter) and 2 (Warm humid summer, mild winter) need to pay most attention to effective cooling. Look for extensive shading, lightweight building materials, effective cross-ventilation and ceiling fans. If the home is air-conditioned, look for good insulation and thermal mass in conditioned rooms.
  • Designs for Climate zones 3 (Hot dry summer, warm winter), 4 (Hot dry summer, cool winter), 5 (Warm temperate) and 6 (Mild temperate) need to achieve a balance between reducing cooling needs in summer and reducing heating needs in winter. Look for northerly orientation, good areas of north-facing glazing with wide eaves, minimal or shaded east- and west-facing glazing, good thermal mass and insulation.
  • Designs for Climate zones 7 (Cool temperate) and 8 (Alpine) need to pay most attention to effective heating. Look for northerly orientation, a moderate amount of glazing with most of it facing north, good thermal mass and insulation. Double glazing is ideal.

Seek advice from an accredited energy assessor for each home on your short list. The advice should compare the heating and cooling requirements for each home and what might be needed to improve them. Find a local accredited energy assessor through the Australian Building Sustainability Association, Design Matters National or House Energy Raters Association.

A couple stands out the front of a home, the man's arm is raised and he seems to be pointing out something in relation to the dwelling.

Spend time assessing existing homes for their potential to be comfortable and sustainable

Photo: Getty Images

Structure, damp and fire

Structural cracking due to reactive (clay) soils or subsidence can reduce the lifespan of the home if left unattended. It also causes heat loss and draughts and can be expensive to repair in masonry construction. Check for cracks, or signs of where they have been repaired, and have them checked by a builder or engineer before making an offer. The more extreme cycles of drought and heavy rain associated with climate change are likely to accelerate the cracking process in areas with reactive soils.

Rising damp is unsightly and can cause poor indoor air quality and health problems. It also reduces the lifespan of a home. Look for any damp walls or signs of mould or mildew. How easy it is to rectify depends on the site and the extent of the problem – in some cases it is relatively simple, but it can be very expensive. Engage a consultant to check and provide advice on how to fix any rising damp.


Check with the local council and rural fire service about the bushfire threat to homes you are considering and factor this into your decision making.


Well over 100,000 Australian homes suffer from termite attack each year and rectification costs range from a few thousand to tens of thousands of dollars, placing termite attack among the most common causes of reduced building lifespan.

Termite risk factors include inadequate subfloor clearance and ventilation, and lack or deterioration of physical barriers including ant caps. Innovative barriers may have been used in more recent homes. In high-risk areas, it is advisable to check council records that these homes were inspected and certified during construction. Ask to see any recent inspection reports and check with the inspector who will have a record of the property.

Your contract should be conditional on receipt of a satisfactory, certified termite inspection in all but the few Australian regions free from termite risk.

Shortlisting homes

After inspecting a broad range of properties, develop a shortlist of properties and compare it to your wish list or brief. Decide which properties best meet your brief or can be adapted cost effectively, and narrow your list to 1 or 2 properties.

Choose a designer or builder with expertise in sustainable design and have them attend your next inspection to identify problems, answer questions and suggest solutions. Ask your expert to help you list and firm up your estimate of the cost of upgrading each property to meet your performance wish list – particularly its thermal comfort.


Be creative in your choices and consider location over size. You can always add to your home, but you cannot relocate it.

Closing the deal

Factor all these costs and considerations into your negotiations. Make offers based on the cost of achieving thermal comfort in addition to your other needs and sustainability goals. Make these costs known to the agent and vendor and be prepared to walk away if limitations are not adequately addressed in the purchase price. By doing this, you are educating the market and helping to change the way sustainable design features are valued in property transactions.

References and additional reading

Learn more


Original author: Chris Reardon 2013

Updated: Department of Industry, Science, Energy and Resources 2020, and Department of Climate Change, Energy, the Environment and Water 2023