Buildings have always been designed and constructed in order to filter the extremes of weather and provide comfortable living conditions inside the building. This is provided in the first instance by the external envelope of walls, roofs, windows and doors. Together these keep out rain, snow and wind; keep in warmth and moderate the entry of light and air. The inside conditions of most traditionally constructed buildings is also moderated by internal features such as chimney stacks, masonry walls, separate enclosed rooms and draught lobbies that together provide additional thermal mass and limit heat loss through draughts.
Traditional buildings are characterised by the widespread use of ‘breathable’ materials which allow moisture within the building's fabric to evaporate freely without damage. This applies to all traditional methods of construction such as solid masonry walls and timber framing that does not incorporate impermeable barriers to moisture within the construction.
However, traditional building materials can vary considerably in their permeability. Brick and stone for instance rely heavily on more permeable lime mortars to increase the overall amount of evaporation. Maintaining this ability of the building's fabric to regulate the moisture levels is fundamental to the effective thermal performance of traditional construction.
Heat-storing ability
The ability of most traditional buildings to store heat is a significant factor in their thermal performance, which is missing in much modern construction. This storage capacity within the structure of the building means it can take up warmth slowly when the building is heated and then re-radiate it as the building cools down.
Unfortunately the thermal performance of a large proportion of traditional buildings has been compromised by adaptations and repairs carried out with the best of intentions but using inappropriate materials such as cement mortars and renders, plastic paints and impermeable waterproofing treatments.
These reduce the building’s breathability and its ability to provide a comfortable internal environment.
The thermal performance of traditional buildings can also be significantly affected by parts of the building becoming worn or damaged over time giving rise to draughts. Gaps in window frames, around doors and around infill panels within timber wall construction are common areas that can significantly reduce thermal performance and comfort.
ventilation
One very important issue to consider is ventilation. In order to accommodate the evaporation of moisture from the building fabric, traditional buildings need more background ventilation than modern buildings. If ventilation is too restricted there is a risk of condensation, mould and even timber decay. Any reduction in ventilation therefore needs to be carefully considered.
