04/13/2009 05:12 am ET | Updated May 25, 2011

Zero Carbon Design and Architecture, But How Low is Zero?

Welsh School of Architecture, Cardiff University

The built environment is key to a low carbon future. Many countries are now planning for a zero carbon built environment, but the question remains "how low is zero?"

It is widely accepted that human activity is the cause of climate change. This combined with the prolific use of natural resources and the production of polluted waste makes human life virtually unsustainable in its current form. The built environment, its construction and operation, accounts for a major part of fossil fuel energy use and the associated carbon dioxide emissions. It also accounts for a large proportion of material resource use and waste production, and the associated emissions. There are a number of reasons for this:

* Economic growth, especially in developing countries, is driving new urban and peri-urban developments and the associated shift in populations.
* As the population increases, people's aspirations are increasing and they desire to improve quality of life through better housing.
* Buildings are a major source of investment. Much of the world's wealth is bound up in property development and ownership.

These factors have resulted in an unprecedented construction boom, during which time we have become very efficient at producing "inefficient buildings." The recent downturn in the global economy gives us the opportunity to take note of what can be done to develop a more sustainable design system giving us economies over the lifetime of the building.

New Design

In Europe zero carbon buildings are the main driver for sustainable design to mitigate against further climate change. This means, over time the net carbon dioxide emissions of a building will be zero reducing energy demand and using renewable energy supplies. The renewable energy system should be part of the development and not come from existing green energy sources. But renewable energy is not always there when we want it. To what extent can we store energy or be more diverse in our use of energy -- use it when it is available -- make hay when the sun shines! We may need to re-engage with the variations of nature.

In the UK all new housing and schools will be zero carbon by 2016. In Wales, the devolved government aspires for all new buildings to be zero carbon by 2011. This is a big challenge and although there are few truly zero carbon buildings to date, there are some good examples.

The Welsh School of Architecture in Cardiff University has been researching sustainable design for three decades. Since the oil crises of the 1970's we have engaged in the design evolution starting with low energy design, then passive design, and now sustainable design. This research has been implemented through the design of low energy buildings with smart facades, innovative environmental systems and renewable energy supplies. We have developed models predicting energy performance at building and urban scale. It is not the design knowledge or technology that we lack, but the confidence to apply what we know -- to break the mould!

Refitting Existing Structures

Past emphasis has focused on the design of new buildings, but new buildings only reduce the rate of increase in emissions. It is the existing built environment where big changes need to be made. We need ways to address the existing building stock, at an individual building and urban scale, to reduce energy demand and decarbonise the energy supply. This is important for buildings and associated infrastructures including water, sewage, mobility, waste and energy distribution. This is where the global community will garner the most dramatic reduction in emissions.

Most sustainable buildings are part of affluent society. It is tempting for designers to focus on "greening affluence"; however it's important to address buildings in poorer areas. Here, it is not only about reducing carbon dioxide emissions, but also about improving quality of life. Even in the UK many people live in what is termed fuel poverty, where more than 10 percent of income is spent on energy used in the home. Affordable warmth is high on the agenda when refurbishing this sector of the existing buildings. For example, in China's rural areas several hundred million people live in houses that are difficult to heat. Farmers in the colder regions spend up to one-third of their income on coal to heat substandard housing. Improving energy efficiency in China's rural housing will improve quality of life and allow the use of alternative decarbonised energy sources such as biomass. Can we bring a better quality of life to the poor without a huge carbon penalty?

Embodied Energy

As a building's operating energy is reduced, the embodied energy, energy required in construction, becomes increasingly significant. Over the lifetime of a "low energy" building in Europe, the embodied energy is of a similar size to its operating energy. In other countries with more temperate climates, the embodied energy can be even more significant. Reducing construction waste is the easiest way to reduce embodied energy, but new materials and more efficient "modern method" construction systems should be considered. Should our zero carbon building definition include a renewable supply offset for its embodied energy over its lifetime?

The Future

The green economy is identified as an area where development without environmental harm can be achieved. Current economic problems may indicate a shift from the growth of urbanisation and consumerism, to a more sustainable balance between rural and urban, and a greener form of growth and wealth creation. As a global community, we must understand the process of sustainable design, the human activity processes that our buildings form part of, and ensure the built environment encourages a broad range of sustainable lifestyles for individuals and organisations.

This future vision for the built environment provides a quality of life that is cleaner, healthier, more socially supportive and economically vibrant. We might not know all the solutions today, but we know enough to begin. We need to think holistically, and share solutions quickly. There is no utopian blueprint for the future built environment, but we know the choices and from these choices our sustainable "zero carbon" future will emerge.