The building sector is the biggest source of carbon emissions causing global warming. Reducing and eventually eliminating these emissions is a realistic goal that requires swift action. Below are resources for preservationists who want to become more involved in fighting climate change by reducing emissions from older and historic buildings.

Confused about terms? We've developed a glossary of terms to orient you to the words of climate work.

Climate Change in Two Numbers

Although climate change is extremely complex, two numbers capture the challenge we face and our progress toward meeting that challenge.

Global Average Temperature (since the pre-industrial era): The International Panel on Climate Change (IPCC), which publishes regular reports on the science of climate change, estimates that global average temperatures have risen 1.1°C above pre-industrial levels. The IPCC’s Special Report on Global Warming of 1.5°C explains the importance of limiting global warming to no more than 1.5°C to avoid risking catastrophic effects.

Human Generated (CO2) Emissions Worldwide: These emissions are the cause of rising temperatures and must ultimately decrease to zero. For 2023, global CO2 emissions totaled 36.8 billion tons, which is a slight increase from 2022. Several organizations track global CO2 emissions and estimate how much remains in our “carbon budget” if we hope to keep global temperature increases below 1.5°C. At current emission rates, we will exceed our carbon budget within a decade. Reducing annual C02 emissions sooner rather than later will stretch our carbon budget over more years, buying additional time to achieve the transition to a zero emissions future.

Data About Buildings and Climate Change

The challenge of reducing the impacts of climate change can seem overwhelming. Understanding the connections between buildings and carbon emissions helps clarify the opportunity for preservationists to make an impact:

• Worldwide, the construction and operation of buildings is responsible for 37 percent of all human-generated carbon emissions — more than the amount contributed by sectors such as transportation or industry. The Global Alliance for Buildings and Construction (Global ABC) compiles annual data on carbon emissions from building construction and operations.
• In the United States the Energy Information Administration tracks energy use and other data for commercial and residential structures. This data shows that building operations are responsible for 31 percent of total carbon emissions nationally.

• Eliminating fossil fuel use in buildings is part of the effort to electrify everything in our economy and communities. For older and historic buildings, this means replacing old furnaces, boilers, water heaters, and stoves that burn gas or oil. Electric heat pumps (either air-sourced or ground-sourced) are more efficient than traditional heating and cooling systems.
• The Inflation Reduction Act offers incentives for property owners seeking to insulate, electrify, and add renewable energy equipment to their buildings.

Embodied carbon emissions occur when the materials needed to construct and rehabilitate buildings are harvested, mined, manufactured, transported, and assembled.

• The Boston Society for Architecture has developed an informative series of webinars on embodied carbon.
• A report from the World Green Building Council, Bringing Embodied Carbon Upfront, details strategies to reduce embodied carbon throughout the design and construction process.
• Building material choices impact carbon emissions, both for rehabilitation and new construction. Rocky Mountain Institute highlights low carbon material options for rehabilitation projects.
• The American Institute of Architects offers guidance on how to reduce material use and climate impacts through adaptation and deconstruction.

• Improving Energy Efficiency in Historic Buildings was one of the first Preservation Briefs published by the National Park Service and continues to provide good advice for how to insulate older buildings, improve the performance of historic windows and doors, add efficient new systems, and build on passive energy features. Other NPS publications provide additional guidance on sustainability and historic buildings.
• A report from the National Trust’s Preservation Green Lab compares the energy savings and financial costs of a range of options to improve the performance of historic windows.

Measuring Energy Use and Carbon Emissions

As building decarbonization accelerates, the ability to predict and track the energy and carbon impacts of the decisions we make about buildings will become increasingly important.

• A growing number of cities and states are implementing benchmarking ordinances and building performance standards that require owners to reduce energy consumption and carbon emissions over time, using reporting tools such as Energy Star Portfolio Manager.