In pursuit of Net Zero: re-evaluating traditionally built rural houses

A major new Welsh research partnership is challenging long‑held assumptions about the energy performance of rural farmhouses and other pre‑1919 homes.

The O Llaith i Gynnes project brings together Cardiff University, Carmarthenshire County Council, their Tywi Centre, and the South‑west Wales Regional Energy Team to show how traditional solid masonry buildings can play an active role in the transition to Net Zero.

In Wales, a significant proportion of homes were built before 1919 and are traditionally constructed with solid masonry walls, lacking a cavity. Impermeable external and internal finishes applied in the 20^th century, including cement based render and gypsum plaster, trap moisture leaving walls damp and far less energy efficient, especially in areas such as West Wales with high levels of wind-driven rain. The project team argues that returning to breathable, lime‑based materials and carrying out routine maintenance can allow buildings to dry out, improving thermal performance even before expensive retrofit measures are considered.

The research will focus on Bremenda Isaf farmhouse, where detailed monitoring will inform a feasibility study on renovation options. The findings will address widespread concerns about the compatibility of traditional homes with heat pumps and other low‑carbon systems. They will also highlight the need to protect embodied carbon and avoid retrofit approaches that risk damp, mould or overheating.

By providing robust evidence, the project aims to influence local government policy, support the training of a skilled workforce and strengthen the case for further Welsh Government funding. The team hopes to show that Wales’s historic homes can remain comfortable, resilient and central to a low‑carbon future.