Sustainable building — more to it than meets the eye


It is universally agreed that focused sustainable living is now imperative to the survival of the human race.
Population growth in the past 50 years has put huge pressure on natural resources, resulting in environmental degradation, notably through climate change.

Everything and everybody on Planet Earth are equally vulnerable to the effects of climate change, and mankind must work together to shrink the collective human carbon footprint back to a sustainable size.

The construction sector is a vast, visible yet essential resource consumer and, therefore, potentially a key player to set the tone for other industries in this respect, according to New Zealand Steel market manager Chris Kay.

“It’s important that everybody in the sector, in particular specifiers, understands the principles of sustainable building and the caution required when making comparisons between different materials,” he says.
When specifying a “smart” or “green” building, both the energy embodied in the building itself and the operational energy requirements of the building’s users must be taken into account.


New Zealand web site SmarterHomes defines sustainable building as “ . . . it meets present needs without compromising future needs. A building material is unsustainable if it is extracted and used in amounts that will cause it to run out in future. It is also unsustainable if its use causes environmental harm that will be difficult or impossible to repair.”

Sustainable building practices result in a smart building: “A smart home is . . . designed, built or run in a smart way. A smart home is warmer, drier, more comfortable with more natural light; safer; cheaper to run, with lower fuel bills; healthier for you and your family; great to live in; easier on the environment. Being smart doesn’t have to cost you more, and can save you a great deal,” the web site says.

Construction industry role players face the challenge of quantifying the total energy used over the life of a certain building material in real time and then evaluating it in the qualitative framework of the building’s future maintenance requirements.

“Total energy” refers to the energy used to extract, process and transport it to building sites, the energy used to build with it, and the energy used to dispose of it at the end of its life. This is called the building’s embodied energy.

The people who will use the building have ongoing energy requirements, too. This is called the building’s operational energy, often referred to as the building’s future-proof qualities.
The idea is to find the optimum level where the two types of energy work together for maximum sustainability of the building in the long term.

Making comparisons

It’s a wide scope — but there are tools to help the building professional do the job of optimising the sustainability of a building. One such tool is life cycle analysis.
Another is the New Zealand-developed Home Energy Ratings system, launched by the Energy Efficiency and Conservation Authority (EECA) in December last year.

SmarterHomes describes life-cycle analysis as considering “the total environmental impact of a material or product through every step of its life — from obtaining raw materials, for example through mining or logging, all the way through manufacture, transporting it, using it in the home and disposal or recycling”.

It factors in a building’s embodied energy but also considers the environmental impacts of manufacturing a building, such as depletion of resources, chemical degradation, energy and water use, greenhouse emissions, waste generation and toxicity to people and the environment.
ISO14040 governs this complex process, widely considered to be the most comprehensive way of understanding a building’s full environmental impact. However, New Zealand-based life-cycle analysis data is not yet widely available.

The Home Energy Ratings system focuses on quantifying the operational energy requirements of a building, making the energy efficiency of a home visible and measurable.
It is an independent assessment of the energy performance of a home, expressed as a star rating, with the potential maximum of six and a half stars.

The assessment includes expert recommendations about the most cost-effective ways to improve the home’s energy efficiency and reduce energy costs, and to maximise the star rating.
EECA is now training assessors and will monitor the effectiveness of the programme.

Making choices

Meanwhile, Mr Kay says it is important for building professionals to understand how to make sustainable building choices, as it is easy to inadvertently compare apples with oranges.
He actively advocates approaching sustainable construction via a comprehensive life cycle assessment.

“Many building products are compared on a cradle-to-gate approach, which only looks at green credentials of the building material to the factory gate.
“To quantify the true impact on the environment of a given product or service throughout its lifespan, a cradle-to-grave approach is required or, even better, a cradle-to-cradle analysis which takes into account a material’s ability to be recycled into a future use,” he says.

“In addition, merely calculating embodied energy is very difficult as there is no standard for doing it, and the modeller can choose what to include and what to exclude, making direct comparisons difficult.

“In this respect, the durability of a material is important. If a product with half the embodied energy of an alternative has to be replaced four times during the life of the building compared with no replacement, then selecting the low embodied energy product would not necessarily minimise the impact of the building.
“Also, keep in mind most figures are quoted for a mass of material. However, in buildings, square metres or lineal metres are more relevant,” he says.

The energy consumed by the occupants of the building is another issue to be considered. It may, for example, be justifiable to use a material that is higher in embodied energy, such as insulation, if it reduces overall heating or cooling energy consumption in the building.

Mr Kay encourages a close look at the credentials of the building material itself, as well as the credentials of the material’s sector and manufacturer.
The specifier may, for example, ask questions relating to the strength-to-weight ratio of the material, its recyclable properties, and the sector and local manufacturer’s policies and reputation in respect of sourcing materials, subsequent rehabilitation practices, waste generation, recycling and disposal, and electricity and water use and conservation.

My way . . . or the highway

SmarterHomes points out building industry professionals who understand the concepts of sustainable building have a definite advantage over those who do not.
It says demand for building professionals with knowledge of, and skills in, sustainable design and building will increase as consumers become more informed and insist on green, or smart buildings. Manufacturers will respond with smarter products and technology.

Treating a building as an integrated system from design stage will certainly save costs and tip the scales in favour of sustainability, and a building professional has to stay ahead, or possibly lose customers.

The web site emphasises “local and central government are increasingly requiring sustainability to be considered when a home is being designed and built. These requirements will increase following the Building Code review.
“Builders who understand sustainable design and building practices now will be better positioned to deal with future changes in compliance requirements.”

Also, international research suggests resale values for low-energy homes are much higher than for other homes.
“This stands to reason,” the web site explains, “as smart homes are better to live in” — and in a consumer gratification-focused world this is perhaps the most persuasive argument of all in favour of sustainable building.

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