How to build 'Net Zero Carbon' buildings.
A NET ZERO CARBON BUILDING is defined as ‘one that is highly energy efficient with all remaining energy sourced from onsite and/or offsite renewable sources' by the World Green Building Council. The New Zealand Green Building Council also believes the carbon emitted during construction should be included in calculations. We discussed in our last blog post about why it is important to consider this as a key parameter of your build, and how it is starting to become a part of legislation for many countries, New Zealand included, in order to achieve their zero carbon commitments. Three core principles need to be considered.
1. Reduce energy consumption and use renewable energy sources.
The thermal design
of a carbon neutral building needs to ensure that it is energy efficient and, where possible, uses natural air flow to cool the interior rather than mechanical means, it also uses renewable energy strategies (eg. solar panels) to offset the carbon use. It is important to design buildings to the site and climate, using passive solar and ventilation principles to achieve these goals.
The Energy consumption
of a building needs to be reduced. Within the building the selections you make for lighting, space heating and cooling all matter in terms of your overall energy use.
Remove fossil fuel use from buildings
Fortunately, in NZ we have an electricity grid that is fairly low in carbon, eg. hydropower, however there are still many forms of heating that use fossil fuels eg. non electric boilers and gas hotwater heating. Replacement with heatpumps, wood stoves and wood fired boilers is actually a lower carbon heavy option for your home or business.
Reduce peak electrical demand
Fossil fuel use increases when there is a winter peak electricity demand. Renewable energy such as solar and wind are variable over the winter. To reduce this dip in renewable energy production, we need to ensure the energy design of the building incorporates good thermal performance so that heating requirements are not as high during winter periods. Compulsory minimum insulation levels in buildings will need to double (at least) in order to achieve compatibility with other nations with similar climates.
2. Quality of materials /recycled materials / volume of materials and waste.
The embodied energy
in the materials of a building is important in a buildings whole lifecycle assessment. EPDs, (Environmental Product Declarations) need to include units of carbon dioxide, so that we know as consumers that what we are specifying is going to meet emissions standards. BRANZ does have some guidelines we can use, but their data needs companies to supply more specific NZ product information. The selection and quantity of materials is important as part of the design and reducing our carbon footprint in construction.
Reduce steel, reduce cement.
A low carbon option is to replace steel and concrete with plant based products such timber or earth products. See our recommendations on more on sustainable material choices here.
Demolition waste and recycling
Encourage the recycling of existing construction materials and incorporate them into new buildings or new materials. We also should be encouraged to renovate existing buildings in order to reduce using new materials where possible.
Adopt a less is more policy
and reduce area/extra features. Consider the base question ‘Do you need it’. This reduces impact of a high volume of materials spread over a larger area.
Use natural materials, local materials and manufacturers
with low embodied energy and transportation miles, and use materials carefully to ensure minimal waste.
3. Measurement, management and verification.
The success of a net zero carbon building goal relies on measuring, managing, verifying, mitigating and marketing scientifically the emissions associated with materials, transport and energy efficiency. It needs to be a common language. We also need to be able to monitor the building through its use. This ensures informed choices when purchasing or designing a building and provides meaningful data on the energy savings that are generated for the owners. The NZGBC have also introduced new certification tools specifically relating to the Carbon zero emissions.
CEMARS and CarboNZero certification
is specifically related to building operations and allows you to ensure that you have reduced carbon emissions and offset any remaining carbon emissions to international standards via Enviromark, which makes a meaningful difference to the atmosphere.
Homestar, Nabersnz, and Green building certification
are several alternative tools available in NZ today that can be used to assess sustainable and green construction (they include a variety of other sustainable principles relating to health, toxicity, resources - not just carbon levels), via the NZ Green council and Enviromark, and they can be applied to either residential or commercial buildings. The living building challenge also offers an overall sustainable assessment of ‘good’ buildings.
For households and families, measuring your existing carbon emissions is an interesting exercise. It’s a tool to assess and look at where your lifestyle could adapt and evolve. There are calculators that can help you with this.
There are also ways of offsetting your remaining carbon load. Some actions (such as planting trees, investing in renewable energy, or using timber) actually have a negative carbon load on the planet (because during their lifecycle they actually USE the carbon in the atmosphere) and can offset any carbon use through travel, construction etc. Although ideally this is something in a beautifully designed carbon neutral house that we would try to avoid if possible.
The future
So how do your build plans fit into this picture of a better environment for the kids in the future? These may sound a difficult list of parameters to achieve, but its actually not that difficult to do in practice. Often just takes a community to realise the importance and value in investing in a positive legacy for the next generation, then demand and insist on change in the quality of what the construction industry delivers to them.
If you would like to find out more about building a Carbon Zero building today, get in touch with us and we will be happy to help you achieve your goals.
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