Gab Learns – Homestar V5
What is Homestar?
Homestar is a rating tool created by the New Zealand Building Council that was released in 2009. It’s somewhat of building standard and a way of analysing or assessing a building to say whether it’s good or bad.
The objectives of Homestar are:
- Establish a common language and standard of measurement for efficient comfortable healthy homes
- Address key sustainability issues such as construction waste, as well as housing quality issues such as adequate heating and ventilation
- Provide advice that enables the building and construction industry to produce targeted solutions that deliver results for the owners and tenants
- Create a value proposition for investment into the attributes that improve the performance
- Raise awareness of the benefits of sustainability
The current version of the Homestar standard is at version 4.1. Version 5 is also currently valid, however V5 is not mandatory yet. The updated version was supposed to be in effect in August of this year but has been extended again until early 2023. With H1 changes also being pushed back, perhaps the two will align and release together. However, with that said, we recommend using the technical manual for V5 and preparing for future compliance.
The Homestar rating tool stipulates how ‘green’ the building is. The older version was a lot more concentrated on the construction waste, location, proximity to bus stops etc. – all things that make the project ecologically sensible, V5 however is a lot more concentrated on the operational functions, how the building performs, and how it operates when people are living in it. More focused on operational carbon than embodied carbon.
What is the difference between Homestar and Greenstar?
Homestar is for residential buildings, whereas Greenstar is for commercial buildings. Similarly to Homestar, the Greenstar standard provides an incentive to build commercial buildings to a certain benchmark, however neither standard is mandatory.
Do the embodied carbon parts of the standard (i.e. material choice and construction waste) not fall on the responsibility of the contractors?
Businesses are generally concentrated on money and contractor margins are fairly thin, so often additional costs like spending money on recycle bins, or separate bins for timber/metal waste etc. tend to get forgotten about. Using a standard like homestar gives incentives to include these extra considerations, but the best way to reduce waste is to design buildings that require less wastage in the build! Designing runs of cladding, sizes of windows, heights of studs, etc. to reduce offcuts or wasted lengths are some examples. This solution can be a cost effective / cost savings tool for businesses, but it requires some thought early in design. If it’s only implemented once the contractor on site, then reducing the amount of waste onsite will require money being spent.
So, why the Homestar hype?
Having a Homestar rating generates a conversation and provides an achievable standard so that when the property is being sold it can be sold with a Homestar rating (great talking point for marketing) and provides buyers with a little bit of an idea as to how the building is going to perform. The older (but still current) version of Homestar was marketed as efficient, comfortable, healthy homes, but the items required for 6 stars wouldn’t necessarily make that the case– a little bit of smoke and mirrors! Version 5 on the other hand requires continuous ventilation, thermally broken windows, and thermal modelling – which are all good things that could give someone a lot more confidence in the operational comfort and efficiency of the building.
What does the number represent in each of the versions?
It’s based on a points system. If you get a certain number of points, you achieve Homestar 6, Homestar 7, and so on. The rating system starts at 6 (being the worst) – 10 (being the best). Existing and older homes (like an air leaky villa) might get a 1 or a 2, but any new builds, and full retrofit projects must start at Homestar 6.
Is Homestar 10 in market?
There are a few Homestar 10 homes, and you would be lucky to find one for sale. There are certain buildings that have been rated Homestar 10, but basically this rating is a passive house building, and usually the person that commissioned the build lives in it long term.
Is Homestar a mandatory requirement?
No, it is not a mandatory requirement – this is something a company, client, or homeowner would choose to do. The interest around Homestar needs to be built, and people need to trust that the buildings are going to be warm, dry, and comfortable. Kāinga Ora (formerly Housing NZ) has designed all their new builds at a Homestar 6 level or above, which is a great show of initiative as they prepare for the future, but to actually get heathy and energy efficient buildings, Homestar V5 needs to be used.
If you have Homestar 6 home – does that mean that your home also meets the Healthy Home Standard?
There are so many different standards and ratings, and they are kind of related, but they are separate benchmarks. The Healthy Home Standards are for landlords to ensure their rental is up to standard for tenants. This includes:
- A heat pump or some sort of fixed heater that can heat the common area of that space to 18deg on the coldest day of the year
- Ceiling and floor insulation
- Draught stopping – making sure windows close
Simply put, if a person is living in a home, they should have these things as a minimum, but it’s only rental homes that require it right now. With Homestar version 5, a house may have these items, but compliance with Healthy Homes is shown separately. Then there’s the building code, which is all the rest of the stuff like structure and lighting and weathertightness, but it actually doesn’t require heating – wild, we know. While clause G4 of the code says you must have fans in the bathroom and kitchen, there is no baseline for airtightness or heating.
Where does H1 fit in?
H1 is the energy efficiency standard which was updated last November and due to be mandatory this November but parts of it have been pushed out until May next year. This standard tries to outline efficient use of energy and sets physical conditions for energy performance, but the updates only really target R-values. R-values are important, but they’re only one piece of the puzzle. In Homestar 6 version 5 you must calculate how much energy the building uses and there are benchmarks for airtightness and ventilation to scale this to, and because it’s being modelled you can how the building performs as a whole.
Where do you access the technical guide for Homestar 6 version 5 from?
This can be found on the NZGBC website, however if you have any questions let us know!
We are moving in the right direction of making positive change in the build industry, and some of the improvements seen in Homestar 6 version 5 prove this – however we still have a way to go. For now though, it’s two thumbs up for version 5.
