Buy Clean Procurement and ENERGY STAR

Workers at a construction site

The building community and others are looking for ways to reduce the climate impacts of the products they purchase. Many are choosing to leverage their buying power to reduce impacts through low carbon procurement policies or low carbon product labels. “Buy Clean” initiatives are an example of policies that promote procurement of products that use less energy or emit less carbon during their lifecycle.

ENERGY STAR can help in the search for products that are manufactured using less energy and support decarbonization.

Energy consumed during parts of the manufacturing process is a significant source of carbon emissions in product supply chains. One way to reduce these emissions is to minimize energy consumption through greater energy efficiency. Understanding the energy efficiency of manufacturing plants involved in producing a product can help in assessing the overall carbon emissions associated with delivering a final product to the consumer.

EPA has developed ENERGY STAR energy performance scores (on a 1-100 scale) to benchmark the energy efficiency of certain manufacturing plants for nearly 20 industries. Plants that score 75 or higher can earn the ENERGY STAR certification, signifying they are among the best in terms of energy efficiency for their industries. The ENERGY STAR score can be an additional metric to inform responsible procurement and support decarbonization efforts. Prior to purchasing a product, ask vendors to share:

  • Whether the product components come from an ENERGY STAR certified manufacturing plant.
  • If the component manufacturers have benchmarked their plants’ energy performance using the ENERGY STAR energy performance indicator (EPI) for their industry.
  • The ENERGY STAR score of the manufacturing plants supplying the components.

ENERGY STAR Plant Certification or disclosure of an ENERGY STAR score can be included in Buy Clean initiatives, procurement criteria, and environmental labels as a credible information to help understand the embodied energy of a product.

What is embodied energy and embodied carbon?

Embodied energy is the sum of all energy associated with producing, maintaining, and disposing of a product. Similarly, embodied carbon refers to the greenhouse gas emissions arising from the same activities. Embodied carbon is another term for the “global warming potential” of a product, which is a lifecycle impact calculated with a process called lifecycle assessment.

When discussing only the emissions generated during the beginning of a product’s life in the supply chain, this is known as the “cradle-to-gate” or supply chain impact. This includes the energy needed or the carbon that is emitted to extract and process raw materials, whether through mining or agriculture, and then to transport and manufacture those materials into a finished product (see figure below). For buildings and for some products, sometimes the scope of embodied energy and carbon is extended to include the energy consumed and carbon emitted when using, maintaining, and disposing of the materials.

Key stages in a product’s lifecycle that consume energy and produce greenhouse gases

Image that shows extraction and upstream manufacturing, transportation, manufacturing and fabrication and construction disposal

Why are energy and carbon metrics important?

Embodied energy and embodied carbon are closely linked. For some products, manufacturing results in large amounts of energy consumption and greenhouse gas emissions. An energy efficient plant may have lower carbon emissions.

However, using less energy does not always mean a proportional reduction in greenhouse gases. This is because some fuels generate more greenhouse gas emissions than others.  Second, the carbon intensity of electricity varies by the generation source. Consequently, two manufacturing plants using the same amount of electricity to produce the same product, but located in different electrical markets, could have very different amounts of indirect (scope 2) greenhouse gas emissions. Lastly, for some production processes, carbon dioxide or other greenhouse gases are released directly into the atmosphere because of chemical reactions that happen during manufacturing process. In these situations, energy efficiency or fuel switching are unlikely to reduce these types of process emissions.

While a carbon metric may seem most fitting for assessing GHGs, assessing the embodied energy of a product independent from its embodied carbon, is beneficial. ENERGY STAR Scores help with that process. Energy efficiency produces the greatest benefit from limited resources so that they can do more good. Energy efficiency ensures that energy from renewable sources is not wasted by inefficient processes. When products are manufactured energy efficiently it frees up electricity so that more people can benefit from renewable energy. Further, energy efficiency in manufacturing plants reduces stress to the electric grid, meaning fewer power plants would be needed to support increasing demand. 

Why are low carbon products and decarbonization important?

Building materials for construction, such as cement, concrete, steel and glass account for 11% of global energy-related greenhouse gas emissions[1]. Similarly, the carbon impacts of many expendable products, such as paper and food, have large carbon impacts from the manufacturing process. In fact, the manufacturing sector accounts for nearly a third of greenhouse gas emissions in the U.S. [2] By purchasing products produced in an energy-efficient manufacturing plant and with lower embodied carbon, purchasers can leverage their buying power to support a lower carbon future.

How are governments and other organizations identifying low carbon building materials and products?

Purchasers are leveraging their purchasing power to align with environmental and social goals. Sustainable purchasing initiatives, such as Buy Clean policies, promote purchasing products and materials that produce fewer greenhouse gas emissions during their lifecycle. This includes products that consume less energy when being used, such as ENERGY STAR certified products, and products that require less energy to produce when being manufactured.

Manufacturers may create Environmental Product Declarations (EPDs) for their products to disclose the environmental impacts of their products in a way similar to nutrition labels. EPDs are based on lifecycle assessments and typically disclose the “cradle-to-manufacturing plant gate” embodied carbon of a product. ENERGY STAR plant scores can serve as an additional metric on the energy performance of the manufacturing plant that can inform organizations’ decision making.

How does ENERGY STAR help purchasers understand the embodied energy and carbon of products?

Often, most of a product’s embodied energy and carbon come from one or more manufacturing plants in the supply chain, as is explained in the table below. In any manufacturing sector, there are plants that use a lot of energy to make a product, and there are plants that consume less energy to produce a similar item. Using less energy is one way to support a decarbonized future.

A manufacturing plant’s efficiency or inefficiency contributes to the embodied energy and carbon of its products. ENERGY STAR provides one way to evaluate the energy efficiency of a manufacturing plant’s operations. ENERGY STAR provides a 1-100 score for manufacturing plants based on how energy efficiently they operate. The ENERGY STAR score indicates how a plant compares to similar plants. A score of 50 reflects average efficiency, 1 reflects lowest efficiency and 100 reflects highest efficiency.

The 1-to-100 ENERGY STAR score is a simple and credible way to understand and compare performance of the energy efficiency of the manufacturing plants that produce products.

Relative Contribution to Climate Impacts by Upstream Lifecycle Stage and Availability of ENERGY STAR score (in cyan)

Material category

Extraction + Upstream Manufacturing


Manufacturing or Fabrication

Structural Steel (e.g. beams, girders)


ENERGY STAR Score available for Steelmaking


Transportation to fabricator


Fabrication (cutting, welding, shaping steel)



ENERGY STAR Score available for Cement manufacturing


Transportation to concrete plant


Mix design (recipe) and concrete mixing

Baking Products (commercial bread and roll, cookies & crackers)


Fertilizer production and degradation in agriculture

ENERGY STAR Score available for Fertilizer production




ENERGY STAR Score available for commercial breads, rolls, cookies and crackers

Pulp and Paper Products






Pulp and papermaking

ENERGY STAR Score available for pulp mills and integrated paper mills

Adapted from Figure 2 of Carbon Leadership Forum’s Environmental Product Declaration Requirements in Procurement Policies[3]

How do I find out whether a manufacturing plant produces products energy efficiently?

2021 ENERGY STAR Certified Facility, This facility meets strict energy performance levels set by EPAFirst, check whether the manufacturing plant where the product is made is currently certified by ENERGY STAR. Certified plants are listed by industry and year of certification in ENERGY STAR’s online registry, the ENERGY STAR Certified Building and Plant Directory. Natural Resources Canada does the same for manufacturing plants in Canada.

ENERGY STAR certified plants are confirmed by the U.S. Environmental Protection Agency to perform within the top 25% of energy performance for similar plants. Certified plants complete a verified application for certification and satisfy regulatory environmental compliance criteria. Certified plants must recertify annually to demonstrate they remain in the top quartile of performance.

What if a plant is not ENERGY STAR Certified?

If a plant is not ENERGY STAR certified, ask manufacturers for their plant’s ENERGY STAR score. The plant with the highest score would produce its products more energy efficiently than plants with a lower score. You may also ask suppliers to include the ENERGY STAR score in future EPDs they produce. 

Product manufacturers can generate a score by downloading the Energy Performance Indicator for their sector at Within the building materials industry, ENERGY STAR scoring tools are currently available for cement, integrated steel, aluminum casting, iron casting and float glass plants. ENERGY STAR scoring tools for asphalt and steel mini-mills are being developed.

For more information on ENERGY STAR scores and the tools used to develop them, consult the technical documentation on the ENERGY STAR Focus Sector pages.

Other Resources

For Manufacturers: How to Disclose ENERGY STAR Scores and Certification in Environmental Product Declarations and Other Resources

[1] UNEP 2019 Global Status Report for Buildings and Construction.

[2] U.S. EPA. Sources of Greenhouse Gas Emissions.

[3] Approximate impacts for: