Building Systems Efficiency | Alliance to Save Energy

Building Systems Efficiency

Built Environment

A lot of energy consumption happens indoors, making buildings an important target for energy efficiency. And the energy efficiency toolkit is getting smarter: emerging innovations around building systems and grid-interactive technologies are combining with proven solutions like high-efficiency windows and insulation to make the promise of decarbonization a reality in the buildings sector. But to get there, we need to do more to push energy efficiency into the market.


Why Building Systems?

Despite decades of efficiency improvements in building equipment and components, there remains significant untapped potential for energy savings in buildings. Achieving the next level of efficiency requires a systems approach – which considers interactions among building components (e.g. heating and cooling systems, lighting systems, miscellaneous electric loads), multiple buildings, and between buildings and the electric grid.

Systems Efficiency Definition

Building systems efficiency is the ratio of (a) the services or functions provided by a building system to (b) the amount of energy that the system consumes directly, taking into account the thermal load imposed on other building systems. A systems-efficient building is a building in which multiple building systems (e.g., lighting, HVAC) are designed, installed, and operated to optimize performance collectively to provide a high level of service or functionality for a given level of energy use or input.

The Opportunity

The buildings sector accounts for almost 40% of primary energy use in the U.S. and globally. Significant energy efficiency gains in buildings already have been made through policies and programs that focus on individual building components (e.g., equipment energy efficiency standards) or whole buildings (e.g., building energy codes). However, building energy consumption continues to rise globally, due largely to a combination of growing floor space and increasing electricity demand from new devices and equipment, including plug loads/miscellaneous electric loads.

Strategies to Promote a Systems Approach
  • Breaking down silos. A systems-oriented approach often requires collaboration across a range of stakeholders – including architects, engineers, designers, developers and building operators – as well as between the building industry and policymakers.
  • Integrating systems. Integration both within and among systems operating in a building is vital to maximizing efficiency gains and opportunities.
  • Optimizing operations through technology. Controls and smart technologies are important for improving the efficiency of many types of systems.
  • Incorporating systems strategies through all phases of the building life cycle. Strategies to incorporate a systems approach should be applied during building design and construction, as well as during the operations and maintenance phases.
  • Thinking outside the building. Further opportunities for systems approaches exist beyond a building itself, across multiple buildings and between a building and the electric grid.

In 2015, the Alliance to Save Energy launched the Systems Efficiency Initiative – a multiyear collaboration among more than 50 entities, including manufacturers, designers and builders, electric and natural gas utilities, federal and state government agencies, and efficiency advocates – to advance energy efficiency in building systems. The initiative produced two reports:

The Alliance also maintains a resource hub for case studies, program guidance, tools, and consenus reports on systems efficiency. Check it out here




Help the Alliance advocate for policies to use energy more efficiently – supporting job creation, reduced emissions, and lower costs. Contact your member of Congress.


Energy efficiency is smart, nonpartisan, and practical. So are we. Our strength comes from an unparalleled group of Alliance Associates working collaboratively under the Alliance umbrella to pave the way for energy efficiency gains.


The power of efficiency is in your hands. Supporting the Alliance means supporting a vision for using energy more productively to achieve economic growth, a cleaner environment, and greater energy security, affordability, and reliability.