In our previous article, we answered the question “What is an Energy Efficient Home?” where we mentioned some of their advantages.

The building standard of New Zealand is behind from where it should be in regards to Health and Sustainability, but this is changing.

NZGBC (New Zealand Green Building Council) developed Homestar, an independent rating tool for assessing the health, efficiency, and sustainability of homes across Aotearoa and we're proud to be members of this organization. We highly recommend checking their website where you can find lots of tools and information. There’s no need to reinvent the wheel in regards to green building.

Last week, we took part in a meeting from NZGBC about the technical updates of Homestar Version 5 and in this article we’re going to share some of them, diving deeper into the topics in future articles.

Here are the main topics discussed in the meeting:

About Homestar
The importance of measuring operational and embodied carbon
Overheating
Waste
How can NZGBC help?
Homestar Registrations and Certifications
Progressive Improvement

1. About Homestar

Homestar is about delivering homes that:

Kiwis deserve
Aotearoa needs
Climate action demands

Homestar is an Independent verification tool of Quality, Health & Sustainability.

For more information check this link Homestar.

2. The importance of measuring operational and embodied carbon

"A typical new Kiwi home emits five times as much carbon dioxide as it can afford to if the world is to stay inside 2C warming. A first-of-its-kind New Zealand study says housing must shrink its carbon footprint by 80 per cent to do its bit to meet the Paris climate accord.

The researchers wanted to know how the carbon footprint of a typical, new Kiwi home compared to what an ideal footprint would be, one that's compatible with the Paris 2C warming limit. The study's lead author was Chanjief Chandrakumar and BRANZ's Roman Jaques also helped." (Click here for the full article).

Embodied carbon is the total greenhouse gas (GHG) emissions generated to produce a built asset. This includes emissions caused by extraction, manufacture/processing, transportation and assembly of every product and element in the asset.

HECC is an embodied carbon calculator very easy to use for standard constructions used commonly in NZ residential construction, developed for NZGBC by BRANZ.

ECCHO (Energy and Carbon Calculator for Homes) is a comprehensive, whole-house, thermal performance and carbon calculation tool based on the Passive House Planning Package (PHPP) developed by the German Passive House institute. This tool forms the primary compliance pathway for several credits.

The building industry must decarbonise and we are all responsible to make it happen.

3. Waste

The best way to deal with it, is to eliminate it in the first place.

50% of landfill comes from construction (4 tonnes per house).
Homestar V5 puts the responsibility on both the designer and builder.
More focus on onsite sorting, and designing out waste.

4. Overheating

Overheating has become a major issue with increased airtightness, glazing and reduced shades and Homestar V5 deals with this by:

Putting mandatory limits on overheating.
Requiring envelope, shading & ventilation system designed to consider overheating prevention.
Requiring mechanical cooling where overheating is very likely.

5. How can NZGBC help?

The NZGBC does advice on the design and building process, provides training & accreditations for Homestar Practitioners (219 active), Assessors (186 active) and Designers (New).

By certifying your building you're showing your commitment to a greener building industry and NZGBC will also provide resources to pitch to your clients.

6. Homestar Registrations and Certifications

These graphics demonstrate the involvement of people in regards to building better quality, healthy and sustainable homes in Aotearoa in the last few years.

7. Progressive Improvement

Homestar is a “live” tool that adapts to the progressive development of the building industry and also to new terms such as embodied carbon and unforeseen challenges such as overheating and waste management. NZGBC encourages a coherent collaborative effort that aligns with science and works towards achievable goals.

Sometimes things that are important have to be left for another day due to economics but when the industry is ready, we need to bring these in:

Better heating and ventilation requirements.
Address thermal bridging
Performance focused water use benchmarks
Improved process & make assessing easy (evidencing).
Accounting for embodied carbon
Designing out waste.

The Homestar rating will help set foundations for EPCs, align with national initiatives and benefit-focused credits & categories.

We'd love to hear your feedback and as we said, we recommend contacting NZGBC to get educated and hopefully involved to raise the building standards in Aotearoa.

Check out our Instagram where we show the progress of our projects driven by sustainability, energy efficiency and beautiful architectural designs.

Thank you for reading!

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