Mitigating the impacts of climate change involves reducing the greenhouse gas emissions that contribute to the problem. Adaptation means designing and constructing new buildings and renovating old buildings so that they can better cope with more intense rainfall, floods and stronger winds.
What are the issues?
The Parliamentary Commissioner for the Environment’s 2015 report Preparing New Zealand for rising seas: Certainty and uncertainty estimated that about 9,000 New Zealand homes stand less than 0.5 m above spring high tide levels - at great risk of rising seas and flooding. Cities with large areas that are particularly low-lying include Napier, Lower Hutt, Christchurch and Dunedin, but smaller centres such as Whakātane are also affected. There are 43,680 homes less than 3 metres above mean high water spring - still at risk.
Flooded homes can become unliveable for long periods - for example, when sewage contaminates stormwater. More than 6 months after the Edgecumbe floods in 2017, 500 homes could still not be reoccupied.
Insurance companies have begun adjusting policies and prices to reflect climate risks. Spokespeople have said that, because rising sea levels cannot be considered as accidents or unforeseen events, resulting damage is not insurable.
Aotearoa New Zealand’s First National Adaptation Plan, launched in 2022 by the Ministry for the Environment, sets out actions for dealing with climate change. Actions involving the building industry and the built environment include:
- Updating Building Code requirements to ensure buildings are designed and constructed to withstand more extreme climate hazards.
- Identifying and adding climate hazards not currently in the Building Code.
- Making it a legal requirement that Land Information Memoranda contain information on the natural hazard risks facing a property.
The Plan, the first in a series that will be prepared every 6 years, can be found on the Ministry for the Environment’s website.
What is BRANZ doing?
BRANZ is playing a key role in examining how climate change will impact our built environment. There are two key recommendations for climate action:
Increase energy efficiency
Our research recommends that, for buildings (whether new or existing), there is a need to improve energy efficiency, decrease the energy supply carbon footprint and manage peak demand. These measures could be taken up by government and industry in a number of ways, such as:
- encouraging passive solar design in all new builds
- providing incentives to improve thermal performance in existing buildings
- reviewing Building Code clause H1 Energy efficiency alongside clauses E3 Internal moisture and G4 Ventilation
- encouraging low-carbon fuel options for space and water heating
- increasing renewables supplying grid electricity
- investigating the feasibility of incorporating carbon performance into the Building Code
- providing ongoing tracking of building carbon performance
- providing additional practical education resources to help consumers and the building industry better understand the implications of design choices from a carbon perspective over the building’s lifetime.
Reduce embodied carbon
BRANZ research has also found a need to reduce the embodied carbon in construction materials, which could be done through measures such as:
- greater application of environmental rating tools such as NABERSNZ and Green Star and tools that facilitate the evaluation of building environmental impacts such as BRANZ’s LCAQuick life cycle assessment tool
- producing less construction waste and increasing opportunities for reuse, recycling or recovery of waste
- incentivising use of materials that provide lower embodied and life cycle greenhouse gas impacts.