Why it is important to make a submission by 28 May 2021
However, we strongly oppose the proposal to remove separate minimum R values for heavy mass walls from the Acceptable Solution H1/AS1, until a fully functional modelling program that can model free running, passive solar designed houses with low-carbon mass materials such as Earth, is readily available, easy and cheap to use. We ask that this part of the proposal be put on hold or earth building be exempt.
This proposal would put unnecessary hurdles in the way of some of the most sustainable and healthy building solutions available, or even lock these out. Given the Ministry’s objective to make building warmer, drier, healthier and more energy efficient, we feel this possible outcome should be taken seriously and not treated as collateral damage.
We are not saying this light-heartedly: Similar decisions about energy efficiency measures in Australia have led to earth being locked out of sustainable building solutions, despite buildings performing well in terms of thermal comfort, cost, carbon, and health. Many once thriving Victorian earth construction businesses were forced into bankruptcy.
Apart from understandably being worried about how the proposed changes will impact the future of our long-standing business, we are primarily concerned about the impending climate crisis, material shortages, and unaffordable housing. Our desire to contribute to solutions to climate change, as well as healthy living, has informed all our professional decisions and actions to date, and is the primary motivator for this submission.
We would like to go further and invite legislators to investigate the opportunities that would be missed if earth buildings would be pushed back into being Alternative Solutions (which now seems to be the trajectory, despite Earth Building having been written into the NZ Building Code since 1998 and despite the many examples of well-performing buildings in the country).
There is the mention of proposed changes encouraging the building and construction sector to invest in new, more innovative materials; but what if some of the best materials get discouraged? We would love to see bigger manufacturers take up some of this already existing technology, which is open-source and has been adjusted to – and tested in – NZ conditions.
Considering that we are in a climate emergency, and loosely based on the findings of the Building for Climate Change consultations carried out by the Ministry in 2020, we feel it is fair to point out that the way Proposal 1 looks at energy efficiency is too narrow and misses very crucial points.
It only addresses operational energy and ignores the embodied energy in building materials.
Embodied carbon however is a very important part of the equation in the near future, if we want to reduce our carbon emissions fast enough to uphold our international agreements and avoid dangerous tipping points and climate chaos.
This figure adapted from Jukka Heinonen is taken from European research and development of energy efficient, load-bearing solid earth construction (CobBauge), and explains this well.
Even super energy-efficient construction methods such as PassivHaus often fail to address this point.
Closer to home, Andrew Alcorn in his doctoral thesis at Victoria University on 'Global Sustainability and the New Zealand House' found - that adding insulation beyond a certain point makes for worse emissions - even when the grid is only 65% renewable as it was when he did the study. With a grid that is 90% renewable the switchover point for making zero difference to emissions (in an electrically heated building) comes at even lower insulation levels - unless you are using carbon negative insulation like straw or wood fibre.
So, there seems to be the requirement to differentiate between Carbon Emissions, and demand on the national electricity grid.
The current model assumes that all heating and cooling is done with electricity. It also only looks at heating and cooling (which accounts for around 30% of domestic energy use), and not hot water heating (which also accounts for around 30%). Wouldn’t it make more sense to have a more holistic view of operational energy to include hot water heating and account for carbon neutral heating and cooling (off-grid or grid-tied renewables and wood)?
If the concern is how the electricity grid will cope with demand during forecasted extreme weather due to climate change, doesn’t it make sense to diversify and also promote solutions that are not vulnerable to power outages, rather than assuming the only way to heat/cool a building is to blow hot or cold air around an insulated box?
We feel that low-carbon thermal mass is a huge part of this equation, and that passive solar design should be encouraged as much as possible. Earth provides thermal mass that is essential for energy efficiency, with the lowest possible embodied energy. Adding carbon sequestering materials (such as timber, straw, hemp) to the mix, allows to fine-tune performance.
Development of Light Adobe
The beauty of the load-bearing Adobe technique is its simplicity. The single skin construction method is cost effective, fast, and quick to dry out; it is covered by the NZ Standards; it is suitable for a wide range of soils.
When H1 was amended in 2008 and the minimum R-value for heavy construction was raised, we were facing a similar challenge to now. Traditional Adobe, similarly to Rammed Earth, is heavy and has a low R-value (1600kg/m3, R0.6 for 280mm walls). These very heavy wall systems are still successfully used to this day by designers who can model and demonstrate H1 compliance. Our response however was that we wanted a product that just “ticked the box” and in fact achieved more than minimum requirement for solid construction.
The thermal performance of earth walls can be optimised for climate by varying density and wall thickness, to achieve the desired thermal conductivity and thermal lag. The challenge is to retain structural strength while reducing the density of the blocks. Only by retaining the load-bearing capacity of the material is it possible to also keep its simplicity and economic advantage.
Our search for solutions ultimately led us to the development of a load-bearing block with much improved insulation properties, but still some thermal mass behaviour (800kg/m3, R1.4 for 280mm walls or R2.0 for 430mm walls). It consists of earth (unfired, clay-rich sub-soil), cellulose fibre (recycled paper pulp or virgin paper pulp) and wood shavings.
These blocks have been independently tested in accordance with the NZ Earth Building Standards, plus in-depth testing was carried out by the School of Engineering of Auckland University, both in the laboratory and on full-scale panels; they have been used in several buildings in climate zone 3 with very satisfactory thermal performance. We feel that buildings of this performance should be an Acceptable Solutions without the need for calculation or modelling.
There currently are no simple tools to demonstrate H1 compliance whilst taking into account thermal mass, passive solar design and natural ventilation. Until there is such a tool, removing the effective R-values for thermal mass materials is creating a real disadvantage for this type of construction that in fact should be promoted. It is penalizing people who deeply care about climate change and healthy homes, by imposing unnecessary extra costs and making things more complicated than they need to be.
Warm, Dry and Healthy Homes
The proposal states that investing in better quality buildings will have many health and wellbeing benefits for occupants. Better quality doesn’t just mean better insulated. It means looking at living environments holistically and making sure that
- Health issues associated with cold and damp homes are avoided (mould)
- Thermal comfort is achieved (radiant heat is perceived to be more comfortable to humans than hot air blown around – thermal mass increases thermal comfort)
- Indoor air is of good quality, incl. avoiding airborne irritants and toxins from building materials (Earth is totally non-toxic, zero VOC, deodorising and ionising)
Earth controls humidity in buildings better than any other material, and its hygrothermal properties have also positive effects on the heating energy demand, beyond its thermal mass properties. The humidity controlling properties of earth have been extensively researched and documented internationally. It is one of the most remarkable properties of earth. Earth is the most healthy building material we could wish for.
According to modelling carried out using the WUFI Plus software, even small changes in materials have an influence on relative humidity and heating demand. Using earthen materials, exposed timber, and natural paints (rather than Gipsum Board and acrylic paint) created drier and warmer (and thus healthier) conditions.
Coincidentally, these materials also have better environmental performance and lower embodied carbon.
Building for Climate Change
There were some key themes identified in the consultation on Building for Climate Change carried out last year that should inform the suggested proposals for changes to the Building Code. At the very least, the suggested proposal should not work against points raised.
It just happens that the earth building materials and construction methods we work with – and into which we have invested years of R&D to respond to legitimate concerns around energy efficiency – perform really well in most of these points.
- Better information about low carbon building
Having to model these buildings would add cost.
- Raw materials, waste and re-using materials
- Building strength and resilience AND low carbon
- Consenting shouldn’t be hard
Not having the 2020 revised standards cited and potentially having to thermally model these buildings moving forward would make consenting more difficult.
- Action to reduce CO2 emissions (people want operational efficiency and 87% agree whole of life embodied carbon should be included)
- Keep things simple
We sometimes wonder if its simplicity is one of the reasons why it is being overlooked. Surely solutions to some of the most pressing problems we face can’t be THAT simple.
Considering we are in a climate emergency, whatever option is selected, we at least need exemptions for lower density earth buildings and accounting for embodied energy (or carbon sequestration) in the Building Code.
Please consider supporting this cause by making your own submission by 28 May!
We decided not to use the submission form supplied, as we found the questions to be too one-sided and there was no space to speak about real challenges that need to be addressed as part of this update.