Doing More with Less

To aggressively reduce our emissions, we are going to need to overhaul our thinking about not only what we build but also how we build.


By Christian Roselund
November 2019

In many cases, the easiest, fastest, and cheapest way to reduce greenhouse gas emissions is to improve the efficiency of existing processes. For industries, improving efficiency often results in enhanced competitiveness, and whether you are a homeowner or running an automotive factory, using less energy means economic savings as well as climate benefit.

This approach of finding ways to use less energy to achieve the same ends has delivered massively in recent decades, and Rocky Mountain Institute (RMI) estimates that 75 percent of the decarbonization from 2010 through 2016 has been the result of improved efficiency. Overall, global energy productivity—the amount of economic activity per unit of energy consumed—of the global economy has been increasing consistently since 1980, but more needs to be done to limit global temperature rise.

Buildings are a key area for improving energy productivity. Nearly 40 percent of the world’s energy and 70 percent of its electricity are consumed in buildings. They are also highly actionable, with many solutions to reduce energy use in buildings, in the materials that comprise them, and in the processes through which they are constructed.

The amount of electricity used per dollar of GDP has been falling for decades, but there is still more work to be done.

Zero Over Time

In the developed world, most of the buildings that will be needed over the course of the next 30 years are already built. As such, to achieve deep reductions, it is necessary to have a strategy to deal with retrofits of existing building stock.

The combination of economic and climate advantages of improving the efficiency of homes was not lost on the Obama Administration, which—as part of the so-called stimulus act in 2009—approved $5 billion for the Weatherization Assistance Program. Less than three years later, these funds had assisted more than one million low-income homeowners with the up-front costs of making improvements.

This was a drop in the bucket; according to an analysis by the Center for American Progress, more than 38 million households were eligible for the program. And this does not count more affluent homeowners or commercial and industrial buildings.

There are perverse incentives that can cause owners to put off investing money in their buildings, even if it will provide savings over the long term, and sometimes it is hard to determine what to do first. When these dynamics are aggregated at the global scale, this means that energy efficiency improvements are happening too slowly to reach decarbonization goals. The International Energy Agency estimates that existing buildings are only receiving energy retrofits at a rate of 1 percent per year versus the 3.2 percent per year that is needed to keep warming below 2°C.

“Investing in efficiency, especially at the portfolio-level, can increase the value of your buildings and provide a strong return on investment.”

To help address this gap, RMI has developed an approach that it calls Zero Over Time to help building owners and managers “right-time” investments. And greenhouse gas reduction is not the only benefit. “Investing in efficiency, especially at the portfolio-level, can increase the value of your buildings and provide a strong return on investment,” according to Cara Carmichael, a principal in RMI’s Buildings Program.

This is one tool among many that will be necessary if we are to retrofit the 113 million buildings in the United States to be compliant with climate needs. However, it’s a critical one because it can allow building owners to make investments in a more cost-effective way than many other approaches.

The Code

For new buildings, there is a lot more that can be done and the approaches vary widely. In recent years, a number of building performance rating systems and standards, such as LEED and Passivhaus, have become widely popular with progressive builders and architects in different nations. But while these can provide a vision of where buildings can go, all of them are elective systems.


For Victor Olgyay, the principal architect at RMI, the fundamental work for building performance starts with codes. “In the United States and other parts of the world, the floor is being raised on building codes,” states Olgyay. And he notes that in California, these are having a profound effect. “Codes like Title 24 in California have done more to reduce building energy use than probably any other single thing.”

“There are a lot of places in the world where there are no building codes at all. In those places, even introducing building codes—that is a big step forward.”

But the most important application of codes is not in Los Angeles or San Francisco. In the developing world, where populations and economies are growing, many of the buildings that will be needed in 2050 have not yet been built, and there aren’t necessarily any rules to follow. “There are a lot of places in the world where there are no building codes at all,” notes Olgyay. “In those places, even introducing building codes—that is a big step forward.”

Olgyay also notes that codes have a tendency to become more ambitious and stringent as time goes on. “A code is put into place and slowly it gets amended,” he explains. “Sometimes it is synchronized with these professional organizations where they have new codes. In a developing country, I would expect that to be the same.”

And while Olgyay suggests that it is possible that some new codes could include energy efficiency requirements in their initial form, this is not certain. “As need or support grows, then they will move forward,” he muses.

Many Paths

But even the most stringent codes only set a floor, and there is so much more that can be done beyond this, particularly with the new technology available today. The Buildings Program at RMI emphasizes four key elements to making better buildings: electrification, dematerialization, distributed energy, and design.

Electrifying building services can greatly reduce the energy load of buildings; 30–80 percent of energy can be saved by electrifying heating and cooling (this issue is treated more completely in the associated article: “Electrify Everything”). When used in combination with the passive design techniques that have been known for decades, this can be particularly powerful.

And, of course, on-site renewable energy generation, such as rooftop solar, can further reduce or even eliminate whatever building energy loads are left after passive design and electrification reduce the load. Here codes can also play a role, as was shown with California’s recent move to require rooftop solar on new residential buildings.

But beyond the services, there is also a tremendous amount of energy bound up in the concrete, steel, and other materials in the buildings themselves. Thomas Koch Blank, a principal in RMI’s industry program, estimates that 20 percent of global carbon dioxide emissions come from the manufacture of material used in construction projects, most of which are buildings. And while the emissions from the process of making cement and steel are dealt with in a different article, there are multiple options that don’t involve redesigning these processes.

Dematerialization can be a key strategy. Although there are companies working on carbon-free steel and cement, there are changes that can be made to the design process to minimize material usage; in addition, there are alternatives to those materials.

Also, the way that these materials are used can change. While many of our current processes involve subtractive use of materials—such as cutting lumber or steel beams to fit and then discarding the scrap—3D printing can instead allow for the deposition of material with less waste.

3D Printing can allow for deposition of material with less waste, as well as the use of new, more efficient forms. Credit:

The forms that we currently use are also not always the most efficient. As opposed to the bulk material approach of flat concrete slabs, 3D deposition can allow for different forms, such as honeycombs. These are only some of the lighter strong forms that involve a lot of empty space, as opposed to solid masses, where much of the material is not enhancing structural strength.

Synclastic and anticlastic forms—which echo the curves in an egg—can also allow for maximum strength with minimum material use. These can result in elegant, organic designs, as seen in the work of pioneering Iraqi architect Zaha Hadid.

And the best choice of forms may end up coming from our new computing power, as topological optimization can find forms to meet certain requirements that use a minimum of materials. Together, these innovations in form and building techniques could be nothing short of revolutionary and present opportunities for architects and builders that were not available 10 years ago.

All about Design

Ultimately, Carmichael says that whether looking at the problems of an existing building or designing a new building, a holistic, integrated approach is needed to maximize efficiency. “Taking a whole-systems approach is key to making a building efficient cost-effectively,” explains Carmichael. “You can’t look at each component separately but must look at how the whole system interacts together.”

“You can’t look at each component separately but must look at how the whole system interacts together.”

Ultimately, design is what ties this all together and can provide buildings that not only use less energy but also are superior machines for living. “These buildings are more comfortable and can be more resilient in power outages,” says Carmichael, speaking of net-zero buildings. “There are a lot of reasons to design buildings to net-zero energy standards.”

Whether it is radically rethinking our construction methods and forms or the simple work of creating building codes that mandate efficiency, our way of building is changing, as it must to meet the new demands of the 21st century.