Introduction: We Have But One Earth

Buckminster Fuller, the futurist and inventor, referred to Planet Earth as a spaceship, with the sun as its energy source. Our spaceship is far more advanced than the NASA shuttles, yet it is finite and delicate. It's our home and we need to take care of it. As Fuller said, "We are all astronauts."

The sun is responsible for all energy on Earth. Our reserves of oil and gas originate from plant materials grown from sun energy hundreds of millions of years ago. These fossil energy reserves are like wealth the Earth has saved for us. In the last 150 years, we have spent over half of this endowment. This is like working and saving for our entire career and then spending half of our lifetime savings in 15 minutes. This is clearly not sustainable; our savings will quickly (in geologic time) run out and we will have to start living within the limits of the energy income that is provided by the sun and quit gorging on the reserves built up over eons. But the more pressing problem is climate change. We have to leave most of the remaining reserves of coal, gas, and oil in the ground if we are to keep global warming within the 2°C (3.6°F) limit agreed to by most of the world's governments at Paris in December 2015. Climate change trumps peak oil.

The Threat of Climate Change

All of us share the Earth's atmosphere. Carbon dioxide (CO2) emissions in China show up in the readings atop Mauna Loa, and emissions from a coal-fired power plant in Ohio affect CO2 readings in China. If we are to address the problem of greenhouse-gas emissions and climate change, it must be done at the global scale. This does not mean that individual countries can't approach the problem differently and implement different solutions, but if we don't all work together, there will be little progress.

We have a special obligation in the United States to reduce CO2 emissions and address climate change, since we use much more energy per person than the rest of the world. With only 4.5 percent of the population, we consume about 19 percent of the world's energy.

Buildings are one of the largest energy users in the United States. Approximately 8.05 quads, or 28 percent of all natural gas consumption, is used directly in buildings and most of this is used for hot water and space heating. Approximately 75 percent of all electricity (9.4 quads) is used directly in buildings for a variety of purposes including air-conditioning, lights, and computers. The primary energy used to generate the electricity used in buildings is about three times greater that the energy that actually makes its way to the buildings, since so much is lost at the power plant and through the electricity distribution network.

In total, buildings used 39 percent of primary energy in 2015. This is mostly electricity and natural gas but also includes smaller contributions of petroleum and biomass. This is a lot of energy, and there are certainly many opportunities to reduce building energy use through smarter design, efficiency, on-site renewable energy, and operation, as discussed later in the book.

US energy consumption in 2014 resulted in 5.4 gigatonnes of CO2 being released to the atmosphere, about 15 percent of total global emissions. Generating electricity resulted in 2.04 gigatonnes of emissions, or 38 percent of the US total. Buildings in the United States accounted for 39 percent of all CO2 emissions in 2014. Transportation needs represent the second-largest share of CO2 emissions at 34 percent, and the location of our buildings within the urban fabric strongly influences this component of energy use (more on this in chapter 8). Industrial operations are next and represent about 18 percent. This includes emissions not only from energy consumption but from other industrial processes such as making cement.

Carbon emissions and energy use track each other very closely. Buildings directly use 39 percent of primary energy and are directly responsible for 39 percent of carbon emissions. In general, if you reduce energy use by 10 percent you thereby reduce carbon emissions by about the same amount. On the other hand, if you increase energy use you increase carbon emissions by the same percentage change.

Buildings represent enormous opportunities to save energy and reduce environmental impact. The green building movement has been under way for almost three decades, starting with the American Institute of Architects' Committee on the Environment in 1990 and the formation of the US Green Building Council in 1993. Energy efficiency is the single most important element of green buildings, but green buildings are about much more than energy efficiency. Green buildings also manage water movement and usage, are sited to avoid sensitive environmental areas like marshes and floodplains, and are efficiently constructed of materials that are sustainably produced or recycled. Green buildings also provide a healthy, comfortable, and productive interior environment that avoids the use of toxic material, meets high standards of air quality and thermal comfort, and provides occupants with abundant daylighting and views of the out-of-doors. Recognition programs such as LEED, Green Globes, and BREAM offer certificates for green buildings that meet their standards.

This book focuses on energy efficiency and renewable energy while respecting the broader goals of green buildings. It also raises the bar for energy efficiency and on-site renewable energy. A zero net energy (ZNE) building is one that uses no more energy on an annual basis than it produces. As can be seen in figure 1–4, the sum of all the energy delivered across the property line must be less than or equal to the sum of all the energy that is exported from the site. Energy transfers that happen inside the property line are not significant. The only thing that matters is what comes in and what goes out. The US Department of Energy (DOE) common definition of ZNE buildings allows the use of fossil fuels, but the production of electricity must be greater than the consumption of electricity by a margin adequate enough to make up for the use of gas, oil or any other non-electric energy that is delivered to the building. ZNE buildings go by other names as well: zero energy buildings (ZEB) and net-zero energy (NZE) buildings. Recognition programs for ZNE buildings are just beginning to emerge. The International Living Building Future and the New Buildings Institute have ZNE recognition programs.

We already have the knowledge and technology to design and construct our buildings to be zero net energy. Zero net energy buildings represent an excellent opportunity to reduce our energy use and help mitigate the impact of...