## 4 Conclusions  
The aim of this paper was to investigate whether hemp-lime could be used to improve the energy efficiency of historic timber buildings in Sweden. The results showed that a 33% reduction in energy use could be achieved in an in-situ situation. This was accomplished without changing the framework, appearance, or material of the render and without drastically changing the hygric properties of the facade. The thickness of the wall was altered within reasonable limits: 10 mm was added to the wall thickness. Ultimately, the only alteration made was changing the lime render to a hemp-lime render. Not only did the renovation lead to a reduction in energy demands for space heating, it also created a more stable indoor climate, with smaller fluctuations in indoor temperature. Furthermore, a discrepancy was found between the calculated U-value based on material properties and the U-value based on energy use data. This indicates that when performing energy use calculations, more factors than thermal conductivity and thickness of the material need to be taken into account. From a heritage values point of view, the use of hemp-lime allowed for the preservation of the underlying timber structure. Even the wooden slats were able to be preserved. Usually, these wooden slats are removed during renovation projects using insulation materials such as EPS or mineral wool, \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Period**} & - & **Room** & \multirow{2}{*}{**T\({}_{\text{min}}\)**} & - & \multirow{2}{*}{**T\({}_{\text{max}}\)**} & \multirow{2}{*}{**Amplitude\({}_{\text{pk-pk}}\)**} \\  & & **n.r.** & & & & \\ \hline \multirow{2}{*}{12 through 19 May 2017} & \multirow{2}{*}{23.4} & A & 20.1 & 23.4 & 26.9 & 2.8 \(\pm\) 0.9 \({}^{\circ}\)C \\  & & B & 20.9 & 23.7 & 26.6 & 2.0 \(\pm\) 0.7 \({}^{\circ}\)C \\ \hline \multirow{2}{*}{2 through 9 Aug 2017} & \multirow{2}{*}{27.4} & A & 24.2 & 27.5 & 29.8 & 2.5 \(\pm\) 0.7 \({}^{\circ}\)C \\  & & B & 24.9 & 27.4 & 29.3 & 1.8 \(\pm\) 0.5 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Temperatures and peak-to-peak amplitudes of indoor temperatures in the two rooms during the two time periods in May and August 2018. Figure 18: Indoor temperature in room A and room B as well as outdoor temperature during the summer, 2 through 9 August 2018.  
as they get in the way when applying insulation sheets. However, when using hemp-lime, it was found to be advantageous to keep the historical wooden slats on which the previous render had been applied. The application technique by which the render consisting of hemp shiv, lime, and water is cast onto the timber structure allows for the mason to decide the thickness, roughness and shape of the surface, which means the character of the historical facade can be maintained. A renovation can be accomplished without damaging the timber structure or wooden slats, and it can be done using local traditional materials and building methods with no difference in appearance to a traditional lime render. This helps preserve heritage values and adapts the structure to newer requirements with both increased comfort and less energy use. Funding acquisition, P.S.-d.B. and K.B. ; conception and design of the work, all authors. ; data collection, P.S.-d.B. ; data analysis and interpretation, P.S.-d.B. ; drafting the article, all authors; critical revision of the article, A.D. and K.B. ; final approval of the article to be published, all authors. This research was **funded by** the Swedish Energy Agency through their research programme _Span och Bevara_, **grant number** 42308-1. The role of this funding source was strictly financial. During the course of the project, two seminars were held as part of the research programme _Spara och Bevara_, where the outline of the project and some preliminary results were presented. This project would not have been possible without the help of masons [PERSON] and [PERSON].