Sustainable construction is our future

New Zealand’s housing stock is a legacy of unsustainable building practice – 900,000 homes which don’t meet World Health Organisation minimum standards, a housing affordability crisis, and now a leaky building epidemic.

About half of New Zealand’s landfill and cleanfill waste originates on building and demolition sites. There is hardly a single building material which isn’t reliant on fossil-based energy for its manufacture and/ or transportation, and the construction and operation of the built environment consumes around 50% of global energy use. Our industry is a major cause of the failure and damage to our population’s health and productivity.

However, there are ‘green shoots’ – green building is in demand by a growing number of property owners, designers and builders, and while seldom sustainable, green buildings are certainly a step in that direction. The sector is growing rapidly internationally, including Australasia, as enlightened building owners ask for green buildings.

Getting it right from the outset

The business case for environmentally sustainable development always starts with the client’s brief. Articulating the ‘functional unit’ the building provides, along with the project vision, is an important first step.

An effective way of achieving this is to specify performance levels for key building attributes. Examples include lighting levels, fresh air rates and temperature profiles. Typically, energy efficiency and user productivity will be two important drivers in the business case, and the performance specification will reflect this.

While the occupants’ needs should always drive design, sustainable design reflects on the project’s social impacts. How will it affect the surrounding community? Will it block views, create jobs, or create pollution? How will construction traffic impact on the community?

Mediterranean-style houses with no eaves built in high-rainfall parts of New Zealand are a good example of buildings that do not reflect the realities of their surrounding environment. A building considered out of context has little hope of being sustainable. This extends to the construction methodology – for example, the use of driven steel piles with the associated noise and vibration is seldom acceptable in a hospital environment.

Defining the variables

When the design phase begins, the range of variables by which sustainability will be measured should be defined. These can include user comfort and productivity, annual greenhouse gas emissions, energy performance, and materials – a menu such as that found in the Green Star rating tools.

Some of the variables are easy to measure and evaluate, while others are difficult. Productivity can be evaluated using pre- and post-occupancy surveys – evidence suggests staff are more productive in a building which is sympathetic to occupants’ needs. In an office environment where salaries heavily outweigh building operating costs, productivity gains will be attractive to the business owners occupying the building.

Whole-of-life energy (for a given performance/comfort level) is an important concept because it starts to tie together some of the other variables the industry all too often focuses on in isolation from the bigger picture, including greenhouse gas emissions, capital and operating costs.

Focus on energy

Energy is used throughout the building process, making it an excellent choice if you are looking for a single variable by which to optimise building design, including:

• Energy expended during the project scoping and design phases
• Initial embodied energy – the energy in materials used in the construction of the building (including transport, site preparation and so on)
• Energy in the waste produced onsite (in 2009, Mainzeal implemented a national minimum target of 50% recycling/reuse of all building materials)
• Recurring embodied energy – buildings are usually stripped and refitted multiple times during their lifespan. All that carpet, gib board, paint, aluminium, glass etc contains huge embodied energy – all influenced by the initial design and layout
• Operational energy of the building throughout its lifespan (lighting, heating, cooling, elevators, etc)
• Deconstruction – what inputs are required to remove/demolish the building and separate each of the elements for recycling/reuse?
• All of the above, minus the energy recovered from recycled materials (e.g. timber could be burnt to produce electricity, or aluminium recycled to make new window frames) at the end of the project’s life.

Mainzeal has invested in software which enables accurate calculations of a building’s embodied energy. Combining this with a whole-of-life operation and maintenance (O&M) model, it is possible to accurately predict the recurring embodied energy throughout the project lifecycle.

We now record the construction waste coming off all of our sites and can use this data to make good predictions about the embodied energy of the waste materials. To complete the picture, we are now working on a project where we have backcasted to determine the energy cost of the man-hours which went into the design and pre-construction work, thus completing the whole-of-life energy model.

Extracting value from analysis

This is exciting new ground for the construction industry. For a century, we have had access to low-cost fossil energy, but energy poverty will arrive in our lifetimes. An energy-constrained future will have a big impact on how we use the built environment.

Manufacturing aluminium, steel, glass and concrete requires massive amounts of energy. Even very conservative estimates of the price of energy between now and 2050 are staggering. Ignoring the future energy cost of construction is condemning the industry to a future development freeze. Not only will new buildings become expensive to build, but existing inefficient buildings will be unviable for occupants.

By modelling and projecting both the energy consumption of a building along with projected energy cost index inflation figures, the business case for lowenergy, passive design is compelling. Add to the mix the long-term price of carbon and a landfill levy, and the value in building green is clear.

The key issue for a building industry which wants to grow is that construction activity is directly related to fossil-energy consumption. Sustainable construction requires the decoupling of growth and pollution. In order to maintain our aspirations of continued growth or even parity, we need to find cost-effective alternatives to the energyintensive technology of the present.

Taking advantage of nature

We need to continue to develop buildings with passive features which take advantage of New Zealand’s temperate climate – like the 5000 sq m Auckland office that Mainzeal is currently building which has no air-conditioning. The building is designed to use about a quarter of the energy of a typical office building, giving it an operational footprint which is inherently less risky for the occupier. Rather than relying on the national grid for energy at an unknown future price, owners enjoy the benefits of convected air and radiated sunshine. The guaranteed price in perpetuity for sun and wind? Nil.

Around the world, the green building market is growing at astonishing rates. McGraw Hill Global Green Building Trends (2008) reports that by the year 2013 more than half of all Asian firms will be building green. In North America, more than 96% of firms expect to be involved in green buildings by 2013, and in Australasia that number is set to grow from 67% in 2008 through to 95% by 2013. To quote the report: “Green building is achieving vast market adoption at dramatic rates in every region of the world.” New Zealand needs to catch up.

As a first-tier New Zealand builder, Mainzeal has recognised the business opportunity green building represents. We continue to push boundaries and lead the industry in sustainable construction.

Smart building owners are moving to a wholeof- life approach and engaging people who can deliver genuine whole-oflife solutions early in the project. Collaborative design processes which bring together the project delivery team, including designer and builder, foster innovation and ensure design outcomes are met or exceeded.

Ross Copland is Mainzeal’s sustainability manager based in Auckland. He started with Mainzeal in 2005 as a site engineer and was appointed as Mainzeal’s first sustainability manager in 2008. He is also the CEO and cofounder of Engineers Without Borders New Zealand, and was awarded the 2009 NZ Institute of Building’s Young Achiever of the Year Award along with the institute’s Innovation Award.