Those of us living in traditional buildings, those built before 1919, may already suspect that our homes are not quite the same as those we see being built today. Solid walls, no damp proof course, sash windows, different brick and mortar, no original bathroom; these are just some of the clues that traditional construction differs significantly from modern construction.
The recent drive to make buildings more energy efficient, warmer and cosier makes sense in both cost and comfort terms but there is a growing body of evidence that applying modern building practices to traditional buildings can make things worse rather than better. So we welcome the recent launch of a new guide from the Sustainable Traditional Buildings Alliance (STBA) on Planning Responsible Retrofit Of Traditional Buildings. This guide gives a broad overview of why traditional buildings need to be treated differently and how best to reduce energy use in an effective way, which is also good for health, heritage and the natural environment.
So why are do we need to treat traditional buildings differently?
Today’s building practices, guided by Building Regulations, are best practice for houses built today. However they make many assumptions which can not be applied to traditional houses without potentially disastrous consequences.
In simple terms best practice in modern housebuilding is a water tight sealed box with controlled ventilation. Traditional houses are built from different materials and in different structural forms so they perform differently.
As the new guide explains: “They usually heat up and cool down more slowly. Moreover they deal with moisture differently, allowing rain, groundwater and internal moisture (from washing, cooking and breathing) to move in a controlled way into and through their semi-permeable fabric. They also rely on sunshine, wind, heating and adequate internal ventilation through windows, chimneys and draughts in order to keep dry. In good condition and with regular maintenance, the system stays in balance. Changes to fabric performance, heating and ventilation, if not correctly undertaken, can change this balance and lead to problems of overheating, moulds and ill health.”
The guide also covers the heritage aspects of a building so the visual appearance can be maintained whilst still making improvements in energy consumption and comfort.
Some of the key challenges with traditional buildings
Moisture and ventilation control are key challenges in many traditional buildings. Reducing ventilation or moisture flow by blocking off a chimney or adding internal insulation can trap moisture leading to damp and mould.
There are solutions for these issues when improving insulation and energy peformance. They include:
- Vapour open external wall insulation
- Moisture open internal wall insulation
- Insulated lime plaster internally
- Mechanical Extract Ventilation (MEV), with humidity sensors in bathrooms / kitchens / toilets
- Mechanical Ventilation with Heat Recovery (MVHR). Air is extracted from kitchens/bathrooms then put through a heat exchanger with fresh air from the outside. The warm fresh air is pumped into living areas.
Installing these solutions can be disruptive in a traditional house so are often best to do when the house is being refurbished.