Two of the most pressing concerns of our generation are housing and the climate crisis. In the UK in particular, the housing stock is in desperate need of modernisation and improved insulation. But this problem isn’t limited to the UK; we need affordable housing that is better for the environment and more affordable to run. But how do we get there?Today we are joined by two guests who are taking very different approaches to sustainable housing. Carl Gish is from Aro Homes, a US startup looking to replace existing dilapidated housing stock with new energy-efficient homes built off-site to Passivhaus standards. Marion Baeli is an architect, author, and board director of UK Passivhaus Trust. She has written about residential retrofits, and as a partner of Studio PDP, she worked on Princedale Road, the first Victorian residential retrofit in the UK to be certified in the Passivhaus Standard.Highlights:Retrofitting existing homes vs. creating new sustainable homes· Marion explains how retrofitting existing homes addresses inefficiency, reduces energy demand, and supports the transition away from fossil fuels.· Carl highlights the benefits of building new sustainable homes, including eliminating constraints associated with retrofitting.· Carl emphasises the importance of constructing environmentally sound homes, given that around 23% of global carbon emissions come from single-family homes.The net-zero challenge: balancing energy and emissions· Achieving net-zero status for homes involves reducing embodied carbon, improving energy efficiency, and harnessing renewable energy sources.· Both guests discuss the need for a unified approach to net-zero construction.Cost considerations: retrofit vs. new construction· Carl highlights how new constriction can offer efficiency advantages and cost savings.· Marion discusses how step-by-step retrofitting is an option to spread costs over time and align with budgets.· Marion emphasises the need for government policies and financial incentives to drive retrofitting initiatives on a larger scale.Behavioural barriers and new technology· Both guests highlight the importance of addressing behaviour as a barrier to retrofitting and the need to motivate homeowners to undergo disruptive home improvements.· Carl introduces the concept of hydraloop technology, which recycles water in homes to reduce water wastage.Resources: Passivhaus Standard Aro Homes Studio PDP Princedale Road; first Victorian residential retrofit in the UK Climate Change Committee Hydraloop Technology