Choosing a certified Homestar home means you’ll enjoy a home that’s warmer, drier and smarter. If you have any questions about how to use Homestar to get a better home, check out the FAQs below.

How much does it cost to get a rating?

Homestar ratings are carried out by Homestar Assessors, who negotiate their own fees. As with any professional service, you should get several quotes and compare suppliers before engaging a Homestar Assessor to carry out your rating. You can find assessors in your area through our Homestar Assessor directory and a brief explanation of certification fees.

I am building a new home – when should I start using Homestar?

It’s more cost-effective to find a Homestar Assessor and start incorporating sustainability at the beginning of a project’s design stage. That’s because the Homestar system centres on certain things essential for any liveable home – insulation, moisture control and good orientation for sun – and these matters are best addressed in design. Also, by going through the Homestar tool with your designer and builder, you will get a good idea of what to include in your plans.

If you’re partway through a project and still want to find out how Homestar can work for you, that’s fine too. Find a Homestar Assessor through our Homestar Assessor directory and they’ll give you advice.

What does the Homestar scale represent?

Homestar is a simple way of representing how warm, healthy and sustainable Kiwi homes are. The scale runs from 1 to 10 stars (illustrated below), and getting a 10 Homestar rating means you have a world-leading home.

It’s important to remember that the overall standard of New Zealand houses is pretty low. At the moment, most Kiwi homes only achieve a 2-3 Homestar rating; a new home designed and built to today’s Building Code will achieve around a 3-4 Homestar rating.

How are the stars in Homestar’s self-assessment calculated?


The online tool for assessing your own home is a simplified version of the Homestar v2 rating tool. Each home’s varying features earn points that contribute to a final score. This score is then translated to a star rating based on three main factors:

  1. Base score: This is the sum of points awarded for each question. When you answer a question in the test, points are calculated based on your answer. Some questions are worth more than others: this is to reflect the relative importance of certain issues to overall sustainability. For example, a lot of points are available for insulation and only a couple of points are available for fruit trees and vegetable gardens.
  2. House size: The base score is adjusted by an overall factor determined by the size of the house and the number of people that could easily live in the house, based on the number of bedrooms. The size of a house is one of the biggest single contributors to how sustainable that house can be. In general, a very large house with only a couple of bedrooms is not likely to be very sustainable.
  3. Mandatory minimums: These are things that a house must have in order to progress up the Homestar scale. There are four levels of mandatory minimums and if they haven’t been achieved, your home won’t be able to move up the scale no matter how you answer the other questions. These essential requirements emphasise the importance of key aspects such as insulation, controlling moisture and using water efficiently.


  1. Basic insulation:To achieve 3 stars or above, a minimum level of insulation must be installed in the home. Due to improvements in the Building Code, houses built since the mid-1990s (when floor insulation requirements were increased) should be built above this standard. Houses built before 1978 (when basic insulation became a requirement) will need retrofitted insulation to achieve this.
  2. Moisture control and good insulation:To achieve 5 stars or above, the house must have good levels of insulation (slightly better than Building Code) and specific measures to control moisture. This includes features such as extractor fans in the kitchen and bathrooms, and installing polythene on the ground under the house to prevent rising damp (for wooden floors).
  3. Water efficiency:To achieve 6 stars or above, the house must include some water-efficiency measures such as dual-flush toilets (with a maximum 6/3 litre flush) and showers with a flow rate of less than 9 litres per minute.
  4. Excellent insulation:To achieve 7 stars or above, the house must have excellent levels of insulation and thermal mass. This is more achievable for new homes or major renovations.
  • Examples of excellent insulation include: wall cavities that are thicker than the standard 90mm to allow thicker insulation to be installed; above-Building Code ceiling insulation that covers all the framework; and high-performance double-glazed windows with thermally broken frames.
  • Thermal mass is any heavy, solid material such as brick or concrete that core store heat. Having tiles or exposed concrete adjacent to north-facing windows is an excellent way to transform some of the sun’s energy into heat and to slowly release this heat into the room.

Why all the fuss about being above Building Code – surely homes in New Zealand aren’t that bad?

Housing is a fundamental human need. New Zealand has high levels of substandard housing, which has resulted from poor regulation of minimum housing standards and lack of maintenance. In 2008 the Business Council for Sustainable Development identified that at least 1 million of the 1.6 million existing homes in New Zealand were poorly performing, meaning they are cold, damp and difficult to heat.

New Zealand also has the second-highest rate of asthma in the world. The impact of our housing on health has been well researched and documented by Healthy Housing He Kainga Organga and the University of Otago. The social cost of injury in the home is estimated to be approximately $13 billion a year.

 Efficient homes can also help you save money on running costs.

  • An average-priced LED could save you $290 over the life of the bulb (source: EECA Energywise).
  • Replacing a 12-litre-per-minute showerhead with one that flows at eight litres can cut your hot water bill by $153 a year, while still offering a comfortable, effective shower (source: Consumer NZ).
  • A dripping tap can waste up to 33 litres each day (source: Watercare).

I’m renting – how can I use Homestar?

Anyone renting a home can use the online self-assessment tool to assess that home. This gives you an idea about how warm, comfortable and healthy it is, and lets you compare it to other homes. You could also encourage your landlord to implement some of the recommendations in the Homestar report that comes with each self-assessment.

My home is highly efficient and sustainable. Why can't I get a 10 Homestar rating on my online self-assessment?

Some aspects of very high-performing homes need to be assessed and verified by a professional before a certified rating can be awarded. The online test is a streamlined version of the certified rating process, and is designed so homeowners and tenants with no building expertise can get an indicative rating. Therefore, not all of the points are available in the online test.

The highest rating available using the online test will vary depending on house size and location, but is generally around 8-9.

What were the results of the 2013 Rental Housing Warrant of Fitness research?

In 2013, representatives from Auckland, Wellington, Christchurch and Dunedin councils agreed to test a draft methodology for a housing Warrant of Fitness (WOF) checklist. A checklist was identified as a key factor in improving the health and safety of occupants, particularly children, from poorer households who are living in sub-optimal housing conditions.

The checklist was created through collaboration between the University of Otago and the New Zealand Green Building Council (NZGBC), in consultation with the following organisations:

  • Beacon Pathway
  • Building Research Association of New Zealand (BRANZ)
  • Energy Efficiency & Conservation Authority (EECA)
  • Centre for Research Evaluation and Social Assessment (CRESA)
  • Accident and Compensation Corporation (ACC)
  • Community Energy Network (CEN).

The results of the test were published in May 2014. 

The checklist below formed the basis for the proposed Rental Housing WOF:

  1. Is there a functional, safe stovetop and oven? (Yes/no)
  2. Is there adequate space for food preparation and storage? (Yes/no)
  3. Is there an adequate supply of hot and cold potable water? (Yes/no)
  4. Is the hot water at the tap 55°C (±5°C)? (Yes/no)
  5. Is there a functional toilet, which does not have a cracked or broken seat, cistern or bowl? (Yes/no)
  6. Is there a suitably located bath or shower in good working order? (Yes/no)
  7. Are there secure or high-level cupboards or shelves for storing hazardous or toxic substances out of children's reach? (Yes/no)
  8. Is there a fixed form of safe and effective space heating? (Yes/no)
  9. Do the bathroom, kitchen and all bedrooms have some form of ventilation to outside? (Yes/no)
  10. Is the house reasonably free of visible mould, i.e. the total area of mould is less than an A4 sheet of paper? (Yes/no)
  11. Are the power outlets and light switches safe and in good working order? (Yes/no)
  12. Is there adequate indoor lighting? (Yes/no)
  13. Does the house have adequate working smoke alarms? (Yes/no)
  14. Have the windows got effective latches? (Yes/no)
  15. Have high windows got security stays? (Yes/no)
  16. Are there curtains or blinds in the bedrooms and living area? (Yes/no)
  17. Do glass doors have safety visibility strips? (Yes/no)
  18. Does the house have thermoplastic insulated cabling? (Yes/no)
  19. Does the house have ceiling insulation to WOF standards? (Yes/no)
  20. Does the house have underfloor insulation to WOF standards? (Yes/no)
  21. Is the house weathertight with no evident leaks, or moisture stains on the walls or ceiling? (Yes/no)
  22. Is a ground vapour barrier installed under the ground floor? (Yes/no)
  23. Is the house in a reasonable state of repair? (Yes/no) 
  24. Is the storm and waste water drainage being adequately discharged? (Yes/no)  
  25. Is there any water ponding under the house? (Yes/no)
  26. Is there adequate outdoor lighting near entranceways? (Yes/no)
  27. Does the house appear to be structurally sound? (Yes/no)  
  28. Are there handrails for all internal stairs and all outdoor steps that access the house, and do balconies/decks have balustrades to the current Building Code? (Yes/no)
  29. Is there fire egress to the current Building Code? (Yes/no)
  30. Is the address clearly labelled and identifiable? (Yes/no)
  31. Are there securely locking doors? (Yes/no)