Within most cities, buildings account for the highest proportion of greenhouse gas emissions.  In order to meet the 1.50C global warming target, it is necessary to seriously address the emissions derived from buildings.  

In essence there are two issues with respect to buildings, that cities need to address.  Firstly, there is the existing building stock, the legacy we have inherited.  These buildings were mostly designed without thought to the climate implications.   Addressing this legacy is essentially a retrofitting exercise to make buildings more energy efficient.  Secondly, we need to ensure that all new buildings are designed to high environmental standards to begin with preferably along passive principles.  
 
The COP26 conference has pushed world leaders to mobilise resources to keep warming to 1.50C.  Essential to its success, is that global efforts are efficiently and effectively allocated to meet the critical timeline. CitiesWork, and Tripleline Consulting, are joining the fight through a series of short papers intended to highlight pressing city related issues. We are drawing on our years of experience to contribute to the global knowledge pool to help shape effective interventions and provide innovative solutions to the climate crisis. 
 
Simon Ratcliffe draws attention to some of the key issues related to buildings. The paper highlights the importance of operational energy during the lifetime of buildings and provides an overview for dealing with legacy building stock as opposed to newly constructed buildings.  This publication is part of the Triple Line Cities Work series.