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New approach to building design

Carbon cost plays vital role

A WORLD-first proposal to require assessment of the overall carbon cost of producing, maintaining and using new buildings is the centrepiece of a new discussion document.
Building and Construction Minister Clayton Cosgrove has invited feedback on the discussion document - the second in the Building Code Review - which includes a proposal to require the 'embodied energy' of building components to be taken into account when designing buildings.
Embodied energy is the total amount of energy used to produce a final product from raw materials.
The new proposal raises the idea of factoring into the design of new buildings the embodied energy of the building's components, as well as the building's lifetime energy use, as a requirement of the New Zealand Building Code.
Such an approach would hold the potential to substantially reduce the 'whole of life' costs of buildings and would have significant environmental benefits.
"The Labour-led government believes New Zealand should aim to be the world's first truly sustainable nation," Mr Cosgrove said.
"We know the way we design our buildings and homes will be central to that effort.
"Every building component, even the humble nail, has a carbon cost, or simply the amount of greenhouse gas emissions that were created in making it. In a truly 'green' building, that cost might be included in the building's overall energy efficiency."
Mr Cosgrove said the government is conscious of the world-wide research underway into the environment impact of buildings, and New Zealand needs to be exploring these issues in-depth to ensure it is on the best possible path.
"Using the projected lifetime CO2 emissions of buildings as the principal measure of resource efficiency under the new Building Code is worth considering This approach would take into account energy and water efficiency, construction materials and construction waste."
Mr Cosgrove said public feedback on the review's first discussion document found that there is widespread support among New Zealanders for a more sustainable and energy efficient approach to building.
He said the new Building Code must be able to stand the test of time by supporting sustainability measures while also keeping costs down and houses affordable.
"Innovations in building technology and construction techniques have advanced significantly since the Building Code was introduced in 1991, and as a result, we expect a lot more from our buildings than we did 16 years ago," he said. "Ideally our buildings of tomorrow will be more energy efficient and therefore cheaper to run through having lower electricity and gas bills, while also being reasonably-priced to build from materials that collectively have the least impact on the environment."
The Building Code sets the minimum performance standards that New Zealand's buildings must meet. That means, for example, the strength of buildings to resist earthquakes or wind, or the maximum temperature of hot water from taps so people do not get scalded.
The Code applies to all new building work on structures as diverse as houses, apartment blocks, commercial buildings, dams, bridges and farm buildings.
Mr Cosgrove urged New Zealanders to get involved with the review.
"Our buildings are part of our national identity, as well as places that we live, work and play in, and the building and construction sector is a large part of our economy.
This is an exciting opportunity to help ensure our ,future buildings meet our needs and suit our climatic conditions, way of life and our communities," he said.
"I urge people to explore the important changes being considered and to comment on this discussion document."
This discussion document, along with the public submissions received, will form the basis of a report to the Minister for Building and Construction by November 30, 2007.
Following further consultation with the public and the building sector, the new Code could be in place by the middle of 2009.
The review of the Building Code is part of the government's suite of reforms to transform the building sector. Other reforms include the introduction of occupational licensing, the accreditation and registration of Building Consent Authorities, the revamp of the Weathertight Homes Resolution Service, product certification, new measures to make homes and workplaces more energy efficient, and investigation of a home warranty insurance scheme.

Other key points

a new Building Code structure with clearly set out minimum performance standards that buildings must meet. This will better meet the needs of Code users, especially architects, building designers, builders and building consent authorities, and help improve their decision-making.
updates and clarifications of existing requirements, to ensure the Code is clear and understood by people involved in building work.
a new way to design buildings for people to be safe in the event of a fire.
a new system recognising that buildings need to meet different performance requirements depending on their importance and the risks to the building users
and society (this takes account of the impact of flooding and climate change). For example, a school would have different performance requirements to those of a garden shed.
consideration of internal space requirements for housing to improve peoples' well being and to also better meet the needs of people with disabilities