While much of the body politic in the United States struggles with its identity crisis on climate change, 2016 marks a threshold in the evolution of climate change policy.

Nearly 200 nations, including the United States, signed the Paris Agreement as parties to the United Nations Framework Convention on Climate Change. 
The actions that are being formulated in the US to reduce, and ultimately eliminate, causes of climate change in the building sector, speak directly to the principles and practices of preservation architecture. Indeed, the stewardship ethic and conservation methodologies of preservation architecture are critical to any strategy. An excellent example of sustainable architecture in preservation projects would be QEA’s work on the National Academy of Sciences. We reduced the national headquarters building’s exterior envelope by enclosing three interior courtyards and sensitively incorporating building integrated photovoltaics into the skylight design. 
Architecture 2030, the advocacy group leading US efforts, prepared Roadmap to Zero Emissions, which outlines a building sector strategy to eliminate carbon releases by 2050.  
Two important details make preservation architecture a key element in achieving 2050 targets. 
First, the Roadmap calls for reducing fossil fuel consumption by 3% annually. Achieving this target means renovating billions of square feet to improve energy-consuming systems and exterior envelopes and increase renewable energy. Based on federal building stock data, this requires each and every US architect to complete the equivalent of a 16,000 square foot deep energy retrofit every year. Following the Roadmap strategy, renovation would double new construction over this period. 
Second, building sector energy reductions must be achieved holistically at all scales: cities and towns, individual buildings, and even building materials and products. In other words, the full life-cycle impact of buildings matter. Buildings represent a huge investment of “embodied” material and energy resources that is too often underappreciated. This perspective is confirmed in The Greenest Building study prepared by the Preservation Green Lab.  
Retaining and improving existing buildings is fundamental to reducing the causes of climate change in the building sector. Developing a deeper appreciation for the value of existing buildings is the first step. Extending their useful service life is the next. The Paris Agreement has heightened the relevance of preservation architecture to a level that can no longer be ignored.