10.6 Buildings

Buildings contribute 21% of global GHG emissions, and they do it in two main ways, known as embodied and operational carbon. Embodied carbon refers to the emissions that come from producing building materials, such as steel and concrete. Operational carbon is what’s emitted in the production of the energy used in buildings for heating and cooling, lighting, and other appliances and devices. As the global urban population grows, many more buildings will need to be built, and the way they are designed will determine how much they contribute to greenhouse gas emissions in each way. The process of constructing buildings also produces emissions, but the growing availability of electric construction equipment will make it possible to eliminate on-site emissions, as Oslo, Norway is demonstrating.

Building materials are extracted from the earth, and most are not renewable. Wood, however, is renewable, and as trees grow, they sequester carbon, which is then stored for long periods when their wood is used in buildings. However, because deforestation is another major environmental challenge, many people are reluctant to promote building with wood as a solution. There are also ways to create building materials out of other natural, renewable sources, as well as to design buildings to require less material in the first place. If you’re interested in this topic, see this video of a TED talk from a Canadian architect working to develop these techniques.

Building operations account for 30% of global energy use and contribute 26% of energy-related greenhouse gas emissions, and this energy use is increasing.^[1] Decreasing energy use in buildings saves owners money on electricity and reduces emissions. The top priority is insulation: if a building loses heat through the walls in the winter or soaks up the sun’s heat in the summer, the heating and air conditioning have to work harder to keep it comfortable inside. Most buildings can have their insulation improved (Fig 1), and new building design can take advantage of physical phenomena to reduce the need for heating and cooling. If you’re interested in the technical details of these design elements, check out this 6-minute video.

The next step in reducing energy use is to heat, cool, and light only as needed and to use energy-efficient appliances. You can watch this 13-minute video to learn about the problems with existing air conditioning technology and the variety of options for improving it.

Heat pumps are a recently developed technology that uses electricity instead of burning anything to produce heat. Electrification is important in every part of the house; for example, electric stoves use less energy than gas stoves and do not pollute indoor air. In addition to technological advancement, improving building efficiency requires a cultural shift, because at least in the United States, many people have very wasteful attitudes and habits: they want big houses, heat and cool buildings much more than necessary, and leave lights and appliances on far beyond when they’re using them.

Buildings can provide habitat for some wildlife species, such as birds and bats that nest on ledges and under eaves. However, many birds die from flying into windows, and light pollution from buildings can disrupt the daily and seasonal cycles of many kinds of animals. For example, artificial lighting can disorient sea turtle hatchlings and cause them to crawl inland rather than toward the ocean. Flagstaff, Arizona and other cities around the world have worked to reduce light pollution and become certified as Dark Sky Cities, protecting wildlife and promoting astro tourism.

Extreme weather, increasing due to climate change, threatens buildings in many parts of the world.^[2] Buildings must be resilient to protect people from disasters, and because each region has its own landscape and natural disasters, customizing buildings’ design based on their location improves their resilience. For example, in a dry region that is prone to wildfires, buildings would be kept safer by having a xeriscaped yard with plants adapted to a dry climate, whereas in a region with frequent floods, growing tall plants around a house would help protect it. On a larger scale, mangrove trees along a coastline can reduce damage to buildings from hurricanes.

City governments can speed the transition to more efficient housing by setting building codes to encourage energy efficiency and, as mentioned in section 2, zoning for multi-family housing, which is much more efficient than single-family homes. Heidelberg, Germany created a district of all passive-house buildings, which are highly insulated and powered by district heating and electricity. Many of the buildings have green roofs, and there are water retention basins to absorb stormwater.^[3] The hi-tech Al Bahar Towers in Abu Dhabi, UAE use a lattice of smart blinds that open and close to shade the interior spaces from the sun, reducing the need for air conditioning by 50%.^[4]

The generation of electricity and heat used in buildings makes up 18% of global energy-related GHG emissions. Solving this part of the problem depends on the energy transition, replacing fossil fuels with renewable energy. Buildings can be a big part of that solution, or at least use less energy from electric grids that rely on fossil fuels, by generating their own clean energy. Globally, there are enough roofs available (on residential, public, and commercial buildings) for rooftop solar PV to provide nearly two thirds of the energy the world currently uses.^[5] In Cape Town, South Africa, electricity blackouts motivated homeowners to install rooftop solar, and the country’s total rooftop solar capacity quintupled in less than two years.^[6] Cities can also create solar farms to provide clean power for people who can’t install their own solar panels.

The many benefits of plants are not limited to designated greenspaces; they can also be applied to buildings in the form of green walls and roofs (Fig 2). The plants filter air pollutants, absorb carbon dioxide, and release oxygen, which provides health benefits both indoors and out. When used on sunny exteriors, plants shade buildings, lowering the internal temperature and decreasing the energy required for cooling. Green walls and roofs can provide some of the psychological benefits of exposure to nature and serve as habitat even in a dense urban area without room for a park. For example, the Oasia Hotel in Singapore has plants growing all over its exterior, covering far more area than the building itself takes up on the ground. For almost two decades, Rotterdam, in the Netherlands, has been adding parks, water storage infrastructure, and solar installations to its many, previously empty roofs.^[7]

Homelessness and slums are major problems around the world, and cities have the opportunity to provide both affordable and sustainable housing. Quezon City, the Philippines, has an affordable housing program that builds good quality, environmentally friendly homes (with parks and gardens in each community) to house thousands of families who used to live in slums.^[8]

Knowledge Check

Take a moment to complete the short quiz below to assess your understanding of this section. Read each question carefully and refer to the section content as needed. This quiz is not graded – it’s simply an opportunity for you to reflect on what you’ve learned and reinforce key concepts.