The third episode of the Building Performance Interactive, "Waterproof breathable fabrics in Low Carbon EnerPHits at scale", will focus on deep retrofit, carried out in a rigorous way to help achieve the EnerPHit target in humid climates such as the UK. This innovative approach to deep retrofit has been designed to be replicable, and carbon conscious, reducing the operational energy demand while minimising the embodied carbon impact. To illustrate this point, cohosts Dara McGowan, Ben Adam-smith, and Mike Jacob will explore the construction and on-site airtightness process with the core team involved in building renovation. Andrew Simmonds - Partner at Simmonds Mills Architects will exemplify how the use of WUFI, PHPP modelling, and AECB PHribbon tools can facilitate the design and accurate calculations of Embodied CO2 for Passive House and retrofits, in meeting the standard. He will also discuss the importance of monitoring real life buildings for condensation. Tim Hulse – Passive House Champion at EcoVert will discuss the sustainable practicalities, insulation, airtightness measures, and type of building components installed to enhance the envelope performance while minimising embodied carbon. The EnerPHit project featured in this episode demonstrates how the retrofit steps can be replicable across all building types to achieve a high efficiency and comfort level.