Discussions about energy transition often overlook the crucial role of reducing the energy consumed to maintain comfortable temperatures in the spaces where we live and work. Remarkably, generating heat, the largest end-use of energy, accounts for 40% of global fossil CO2 emissions, with the majority of this heat used in buildings. About half of the energy used in buildings is for their heating and cooling, and because fossil fuels still meet the bulk of heating energy demand, this contributes to about one-fourth of global energy-related carbon emissions annually. Addressing this challenge by improving building efficiency and reducing thermal losses is arguably the most critical step we can take to facilitate the energy transition. However, strong policies or targeted programs to this end are largely absent worldwide. A transformative solution is the adoption of the Passivhaus standard for new and existing buildings. Retrofits to meet this standard could drastically reduce energy requirements for buildings, accelerating our progress toward the energy transition. In this episode, we are joined by Es Tresidder, a Passivhaus consultant who works with an architecture firm to advance the use of the Passivhaus standard and techniques. He walks us through the Passivhaus standard and how to meet it. He also shares the story of the ‘deep retrofit’ performed on his own house in the rainiest and coldest part of Scotland, transforming it into a home that is far healthier and more comfortable, all while significantly reducing its energy consumption.