Targeting Net-Zero Emissions

The world’s climate goals require reducing greenhouse emissions to zero by 2050. A new standard from the International Organization for Standardization explains how.

Rooftop solar panels on homes in Kaupuni Village, an affordable housing, net-zero community in O'ahu, Hawai'i

Credit: Dennis Schroeder/NREL, 57705

To combat the worst impacts of the climate crisis, the world needs to achieve net-zero greenhouse gas (GHG) emissions before 2050, and we must get halfway there (or better) by 2030. One way we can kick-start these necessary GHG emissions reductions is to create standardized climate targets for each organization—be it a region, a utility, a company, or even a family.

But how can these targets be established and translated into action plans that the organization can carry out? A new standard from the International Organization for Standardization (ISO)—a document called ISO/PAS 50010—explains how.

Net-zero as a climate protection policy

The ISO is an independent international organization comprised of 167 national standards bodies that develop voluntary international standards for various global challenges, such as climate change. Net-zero energy (NZE) was first set forward as a goal by Architecture 2030 in 2005 as a tool for meeting globally accepted climate goals. The NZE concept was that if a facility—such as a building—produced as much renewable energy as it consumed in a year, it would produce no net emissions. If all buildings did this, it could eliminate the building sector’s nearly 40 percent contribution to GHG emissions.

Even at the time, when we thought that the best target for global warming was 2 degrees Celsius, not the current 1.5 degrees Celsius, the perceived urgency of the climate crisis, coupled with analysis of the great opportunities for reducing emissions in buildings, led inexorably to a realization that we needed to reduce energy use in buildings to net-zero by 2030. It was not long after that we saw net zero buildings as a step toward achieving net-zero in all sectors by 2050. And we began to see that net zero energy did not necessarily yield net zero carbon, which is really the global goal. Climate change is happening in the here and now, and we need ambitious actions to reduce its impacts.

One can see the need for net-zero energy by 2050 and 50 percent or better reduction by 2030 goals from the graph below. The impact on climate is given by the area under the curve. It is apparent that to keep that area, which represents cumulative emissions and thus the amount of climate change, consistent with the 1.5-degree Celsius curve, what matters most is what we do by 2030. This is why an international standard on net-zero is so important now.


Net -zero energy has attracted rapidly growing interest around the world. Growth rates of projected and verified zero-energy buildings are continuing to be high. This progress has occurred despite a near absence of incentives or mandates in most parts of the world. New Buildings Institute has been tracking the data on NZE buildings in North America. Its database allows us to observe that NZE buildings may not cost more to build than conventional practice, but they provide non-energy benefits such as comfort, health, etc.

In South Korea, new buildings were mandated by law to be net-zero energy. From June 2017 to December 2022, 2,800 buildings were certified to meet the net-zero standard. For publicly owned buildings, zero-energy performance was mandated starting in 2020. For privately owned buildings, zero-energy performance will be mandated beginning in 2024. The zero-energy performance requirements will be reinforced by increasing the specified energy independence rate (the amount of a building’s energy produced by renewables), encouraging more renewable energy generation and reliance on Energy Management Systems to improve energy performance continually over the years.

Net-zero goals are increasingly found in buildings, industrial facilities, regions, and whole countries. Throughout the world, many facilities have transitioned from fossil fuels to green energy. ISO 50010 is intended to accelerate this trend and to provide an objective standard to demonstrate that organizations truly are meeting the energy and GHG (or “carbon”) goals they claim. The standard thereby helps to create new markets that advance the business transformation to green energy.

But just what does zero mean?

The literature on this subject can lead to confusion. Some analysts look at net-zero energy as the goal and assume that emissions are reduced in proportion to energy use. That was pretty accurate in 2005 when the zero concept was developed but it is no longer true. As the electricity supplies around the world have gotten cleaner, a kilowatt-hour (kWh) of electricity produced at some hours of the year is a lot less emissive than it is at other times. Because there is so much new solar and wind power on the system, a kWh generated at 10 a.m. produces almost no emissions (at least on clean grids such as California’s) while a kWh produced at 8 p.m. in August usually emits much more (approximately five times more than average).

It is important to note that while the net-zero energy concept originated with buildings, it is equally applicable to other sectors, including industry and transportation companies.

What is a “higher level of zero”?

The changing grid and how consumers of energy enhance or detract from its renewable energy compatibility are two of the reasons that more and more guidance and policy papers on the subject describe the main goal as net-zero emissions, usually referred to as net-zero carbon. (Carbon dioxide is not the only greenhouse gas of significance but in essentially all discussions, net-zero carbon means net-zero GHG emissions.)

Net-zero carbon (NZC), it became clear, was a more ambitious goal, and many building designers and energy policymakers jumped to this goal to distinguish their creations from the less societally valuable goal of NZE.

In response to this new reality, different versions of NZC have been proposed by conference speakers at international meetings that include zeroing out construction emissions (the emissions of construction equipment and activities plus the emissions to produce the wood, concrete, steel, etc., used in constructing the building). A complete life cycle analysis (LCA) would also include transportation energy to get people (and goods) to and from the building or construction site, as well as other energy-intensive inputs such as water. I pointed this out in papers published in 2010 and 2012. (Follow the links, click the author index tab, and search for “Zeroing in on Net-Zero Buildings: Can We Get There? How Will We Know When We Have Arrived?” and David B. Goldstein for the 2010 paper and “A New Net-Zero Definition: Thinking Outside the Box” for 2012.)

These more advanced goals in ISO 50010 allow for a more structured way of looking for and targeting continual improvement beyond NZE. Strategic energy management (SEM), with its emphasis on continual improvement, provides such a pathway, and ISO 50001, the related international standard on SEM, is the basis for 50010. I published a conference paper that suggested a taxonomy for incorporating SEM and net-zero into a single program in 2019.

ISO 50010 as a path to harmonizing the zero concept

ISO 50010 asks organizations claiming net-zero performance to do several things. First, it asks them to establish an Energy Management System that seeks continual improvement in measured performance over the years. This is a basic requirement of SEM.

Next, it asks that the performance be tracked using performance indicators that say “zero” when the net-zero goal is reached. This specification allows the simple establishment of intermediate goals for future years, such as 2030. If an organization’s goal was 60 percent reduction in carbon emissions, then the indicator would have to register this 60 percent savings from the base year in order to comply with the goal.

Finally, as it states in the Introduction, “It distinguishes between several different scopes and boundaries for…different net-zero goals and their targets, which are increasingly effective at reducing…emissions, and correspondingly more difficult to achieve.” It asks the organization to set goals for future years based on achieving zero emissions, measured progressively more broadly, as shown below. And it suggests continual improvement from the lowest level to the higher levels by considering:

  • NZE as an annual average;
  • NZE based on hourly energy consumption at the power plant supplying electricity;
  • NZC that calculates the marginal energy inputs to the grid on a time-of-use basis, as well as the greenhouse gases, specifically methane;
  • NZC that measures the emissions required to construct the facility, and the emissions embodied in supplies that the organization purchases (for example, parts for a manufacturing facility or water or food for preparation);
  • NZC that includes emissions from the transportation of supplies and people to the site;
  • NZC that takes into account downstream emissions, such as the emissions involved in future demolition of the facility or the use of the products it produces.

The process can be visualized by looking at the figure below (which simplifies the levels to retain readability):

The rungs of the ladder in the figure are the four levels of NZE/NZC listed above. The verticals represent the process of continual improvement with specified goals to be met in planned future years. The organization has the latitude to decide when these more-ambitious goals will be met.

This figure does not suggest the need for developing additional standards for NZE/NZC. Instead, it represents a classification scheme for existing ideas. What is new in ISO 50010 is the structure of thinking about them in the context of continual improvement. This allows the varied definitions and standards for NZE and NZC to be mutually supportive and helps avoid the counterproductive arguments that “my definition of zero is better than yours.”

Conclusions and recommendations

ISO 50010 is a new tool that can help the world meet ambitious carbon emissions reduction goals in two ways:

  • The net-zero energy concept it embodies makes efficiency visible and encourages renewable energy use.
  • It provides an internationally recognized standard for how an organization can claim and document net-zero performance.

The documentation aspect is important, as some organizations have been criticized over how well they truly meet their carbon neutrality goals. In just one of many examples, a company was criticized for relying on cheap carbon offsets of questionable validity. Compliance with 50010 provides a much-needed standard for what actions are considered good practice and which ones should be discounted or disallowed.

And most important, it encourages more ambitious goals for climate stabilization and continual improvement to increasingly comprehensive levels of net-zero emissions.

Related Blogs