Most churches in Norway are both parish churches and museums. The building, its interior and artefacts are an important part of the Norwegian cultural heritage. The users reasonable demand for comfort, which a.o. means heating in the church, creates a climatic stress on the church as a cultural monument. Information on painted wooded mediaeval artefacts in the churches confirms what experience has shown, namely that painted wooden artefacts in heated wooden churches has a greater need for conservation than artefacts in unheated wooden churches. Altering the heating routines would appear to satisfy the climatic requirements for the artefacts and the users' requirements for comfortable warmth. By reducing the climatic stress in the heated churches to a level corresponding to that in the unheated churches, a reduction in the accumulated conservation requirement of 19per thousand can be achieved. Altering the heating routines is therefore the same as preventive conservation, which means: - less resources are needed for remedial conservation-work and the objects are preserved for a longer time in a more original state. Altering the heating methods also saves energy. A full-scale test with localised heating in a stave church has produced an annual energy saving or 37per thousand. -- SCMRE