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What do we mean by ‘green’​?

13 December 2021

The Green Star points system is under review so it is timely to ask; what does ‘green building’ mean to you? And therefore, what weightings should be given to the various ways to make buildings green?

Green Star has evolved over the last decade or so, and until now it has been voluntary. However, with government planning to mandate Green Star 5 for its own projects, I have started to examine the system closely. Sometimes a fresh set of eyes can help these tools stay relevant to what the general population expects them to achieve, as well as provide fresh perspective. One of the other reasons I have started showing interest is out of frustration at seeing projects heralded for their Green Star rating yet which are fundamentally destructive to the planet through their unrestricted usage of high-emission steel and concrete structures.

NZGBC CEO Andrew Eagles assured me this would be addressed in the current review of the Green Star points. And so it was with interest that I have reviewed the consultation paper and went back to basics to ask; what does ‘green’ mean nowadays?

As a general observation I believe nowadays people expect ‘green’ to primarily mean A/ reduce Climate Change and B/ sustainable and not polluting the environment. These should be the key tests upon which design initiatives should be referenced against for inclusion in the system and the allocation of Green Star points.

Of the above two categories, indisputably Climate Change is the single most important factor impacting the future of the world and building design. Climate Change causes can be further broken down into two key emissions areas; Operational Carbon (the energy used by the building’s operation) and Embodied Carbon (the carbon from the choice of materials, their transport and the construction process). These will each contribute around 50 percent of a building’s global warming contribution between now and 2050.

If ‘Climate Change’ is the biggest challenge and therefore the biggest incentive to change building design, then it at least requires 50 of the 100 points on offer in the Green Star system.

That being the case, and ‘Embodied Carbon’ being 50 percent of the cause, then it follows that Embodied Carbon should represent 25 percent of the total 100 points, and Operational Carbon another 25 percent.

So how do the proposed new Green Star points stack up to this logic? Operational Carbon has 23 points available. Pretty close.

Embodied Carbon on the other hand has just 9 points – around one-third of what its logical weighting should be. This is incomprehensible. There are more points for managing potable water, 10! Reducing water use is nice, may save a bit of money, maybe worth a few points, but it pales in comparison to the importance of Climate Change and the 50% contribution which buildings make through Embodied Carbon emissions.

Not only that, when calculating Embodied Carbon of materials, the biogenic carbon sequestered in products such as wood cannot be included in the calculations. Again, this is incomprehensible and goes against all international approaches when the wood is sourced from sustainable forests. Wood is made from carbon from the atmosphere. using more of it sequesters more of it.

Excluding biogenic carbon puts wood on the same standing as concrete and steel, and as such does nothing to deter using high-emission materials, and – importantly – does nothing to push high emission materials to reduce their emissions.

But wait, there is a crumb for the sustainable material sector to fight over. There is 1 point for ‘Long Term Carbon Storage’. Wood can claim 1 point! 1 point is all that is available for solving 50% of buildings’ contribution to climate change.

Let’s take a look at what else gets 1 point; Indoor surface illuminance and glare reduction each get 1 point; having Views gets 1 point, light pollution to night sky and Building Information each get 1 point; having high quality staff support for responsible construction practices gets 1 point, to name just a few that NZGBC ranks as important as Long Term Carbon Storage.

Clearly this Green Star reset needs a complete re-think about what it means to be green. I’d start with the ’50 points relating to Climate Change’ approach above and half those relating to Embodied Carbon. That is what I will be proposing in the consultation that closes on 23 December.

Fortunately developers are not waiting for the Green Star system to lead the way. We are seeing a huge uptick in sustainable material use in projects in design now. Developers wanting government tenants are targeting mass timber as a means of complying with the ‘lowest emission option’ policy announced in June. Last week it was fantastic to read of the Queenstown Lakeview/Taumata project and its plans for the precinct to be a “national exemplar of sustainability, incorporating European-inspired mass timber construction in place of concrete and steel.” Great leadership from the sector.

Come on NZGBC. If you can’t lead with Green Star, at least try to keep up. – By Marty Verry

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