This study investigates the potential of fast-grown spruce (Picea abies) as an insulation material in historic buildings, aiming to evaluate the relationship between density and thermal conductivity. The background of the study lies in the need for sustainable and efficient insulation materials that can be used to improve the energy performance of buildings while preserving their historical character and aesthetic value. Fast-grown spruce has a lower density then the lowest available in the Swedish standard for materials heat conductivity.
The methodology included both laboratory analyses and field studies. In the laboratory part, a hot-disk instrument was used to measure thermal conductivity, followed by calculations of density and moisture content. The field studies were conducted to identify practical applications and challenges in using fast-grown spruce as a construction material. These studies involved inspections of buildings constructed with fast-grown spruce and interviews with those responsible for their construction to investigate its potential functionality as a construction material.
The main results from the laboratory analyses showed a strong correlation between density and thermal conductivity, indicating that fast-grown spruce, with its lower density, has improved insulation properties compared to slow-grown spruce. The field studies confirmed that fast-grown spruce can be used as a construction material in buildings, but also pointed out its tendency to exhibit greater movement during drying, which can be accounted for to prevent issues during the drying process.
The conclusions suggest that fast-grown spruce can be a valuable addition to existing insulation materials due to its improved insulation performance. The study recommends further research to examine long-term degradation effects and the material's moisture properties, which are critical for its practical use in buildings. Additionally, further research should investigate the ability of fast-grown spruce to serve as a substrate for plaster, both for clay and lime-based plasters, to determine the wood's compatibility with these materials.