Our 'world-leading' proposal to count and cut building emissions
Do you know how much carbon will be emitted by your home or office over its lifespan? The Government's green building overhaul, announced this month , aims to tell you that and set a slowly sinking limit on emissions. As houses, factories and offices contribute an estimated 20 per cent of the countrys carbon footprint, an industry revamp could make a significant difference to emissions. The plan to measure and cap what the industry calls embodied carbon greenhouse gas produced by a buildings materials, construction, maintenance, demolition and waste disposal is one of several initiatives in the Building for Climate Change work programme . Its an ambitious plan by global standards. Some countries, such as France , have voluntary schemes to measure and reduce embodied carbon. READ MORE: * Government tells builders: time to go green * Covid-19: Trains, traps and pink batts the govt's array of climate-friendly spending options * New houses emitting five times too much carbon study The Netherlands requires a buildings carbon footprint to be calculated , but sets no limits. Others, including the Czech Republic, Denmark and Germany, are considering similar proposals to our Governments, said building life-cycle expert Chanjief Chandrakumar . But so far only cities, including Vancouver and Zurich , have introduced regulations to measure and reduce buildings whole-of-life carbon footprints. Embodied carbon limits will take the country in the right direction, Chandrakumar said. The initiatives to use less energy and water are also important, he said. The typical building in New Zealand has a lifespan of about 100 years, whereas European structures might only last 70 years, he said. That means todays building efficiency standards will impact the countrys energy use well into next century. If the world is going to restrict global warming to within 2 degrees Celsius, Chandrakumars research found the average new-built detached Kiwi home needs to emit five times less greenhouse gas . If you consider 1.5 degrees Celsius, which is referred to in the Zero Carbon Act and is our Paris climate change target, then its more than five times, he said. Its not only the climate that will benefit, Minister for Building and Construction Jenny Salesa said. Houses will be warmer, drier, and cheaper to run, she said. If we do nothing we will continue to see children in hospital with preventable illnesses caused by damp and cold living conditions, we will have homes not being able to withstand the impact of climate change, fewer jobs will be created, and we will be locking in higher emissions and unnecessary waste for decades to come. NZ Green Building Council chief executive Andrew Eagles said embodied carbon limits are a game-changing concept. Even if they do half or two-thirds of what they talk about here, its going to be the biggest change the Building Codes seen in 50 years, he said. We say, bring it on, lets get stuck into it. Already, there are simple ways the construction sector can reduce the carbon footprint of a home or building, Eagles said. You can substitute products, so rather than using as much concrete or steel, you use more timber, because timber sucks up carbon and then locks it in. Or you can produce steel and concrete in a way that produces less carbon emissions. But in order to meet slowly sinking limits, the industry needs a standardised way to calculate the carbon footprint in a structures design phase. The sector also requires time to plan for the new mindset, Eagles said. Theres a bit of a balancing act if you go too hard, then the industry cant prepare in time. The Ministry of Business, Employment and Innovation, which oversees the Building Code, will be working closely with builders and designers on the proposals, ministry building system performance general manager John Sneyd said. As we develop our ideas about this, its critical we do so alongside the sector. The ministry plans to increase efficiency standards and decrease emissions in stages. Although the first changes, to boost insulation and window efficiency, will be consulted on and introduced next year, the ministry hasnt outlined timeframes for its other proposals, including limiting embodied carbon. We cant expect to go from zero to 100 in one year or five years. It is going to be an increasing in standards and expectations over a period of time, Sneyd said. One of the proposals would require councils to consider how a structure will deal with the likely impacts of global warming, such as intensifying rainfall, when assessing a building consent. This could limit developments in areas at risk of sea level rise, which experts have called for . That concept of location-specific building is not new. For example, you have high seismic zones and high wind zones, which potentially bring into effect different parts of the Building Code, Sneyd said. Although the proposals would make a big difference to new houses, Eagles said the countrys existing homes need to be brought up to scratch. Its really important that we build zero-carbon homes and buildings, but our existing stock absolutely needs a retrofit. The Building for Climate Change programme does not propose changes to current houses or offices, but the work may need to be supported by changes to existing buildings, according to the ministrys statement of intent. Chandrakumar also urged the Government to consider incentives to downsize homes, as a lot of land will be required to house our growing population. The average detached Kiwi home is 190 square metres, compared to 70sqm in Denmark, he said. We should be thinking how we best use our land in New Zealand. We cant just clear all land to build houses.