# A Methodology for Determining the Rehabilitation Needs of Buildings
## 3 Results and Discussion  
In accordance with the proposed principles of the methodology for Determining the Rehabilitation Needs of Buildings (DRNB), an analysis of rehabilitation needs was carried out for 50 residential buildings in Zielona Gora (a city in Poland, population 140,000). All tested buildings are made in traditional technology. The buildings are characterized by similar material and construction solutions. The buildings are 3-storey, the walls are made of solid brick, with wooden ceilings and stairs, a wooden truss framing, roof covering with ceramic tiles. The buildings were built in the years 1850-1915 as town houses. Some of the buildings are in the register of the State Monument Protection Service. The manager of all the analyzed buildings is the Department of Public Utilities and Housing in Zielona Gora. Periodic technical condition assessment [46] was carried out by experts for all buildings. During the assessment, percentage wear of the technical condition of individual building elements was determined (Table 8). The method DRBN uses these results. For the buildings studied, a cultural value index of 1.0 was adopted for buildings constructed before 1900 (for 68% of buildings), and 0.0 was adopted for the remaining buildings. A location indicator of 1.0 was used for buildings located in the city center (for 20% of facilities), and 0.0 was used for the remaining buildings. Appropriate calculations were carried out. The results are the numbers specifying the rehabilitation needs of the 14 elements in each of 50 buildings. The results are shown in Figure 1. The results obtained are indicators of rehabilitation needs. The indicators have been arranged from the highest to the lowest value. The order indicates the rehabilitation needs of the elements in the buildings under study. In this order, rehabilitation of all building group components should be carried out. \begin{table}
\begin{tabular}{c c c c c} \hline
**No** & **Element Building** & **Average Value** & **Minimum** & **Maximum** & **Standard Deviation** \\ \hline
1 & walls & 46.1 & 30 & 70 & 11.4 \\
2 & ceilings & 46.3 & 30 & 80 & 12.7 \\
3 & stairs & 45.2 & 25 & 90 & 14.4 \\
4 & roof construction & 44.6 & 25 & 85 & 15.6 \\
5 & roof covering & 48.0 & 0 & 75 & 16.9 \\
6 & gutters and drainpipes & 53.7 & 30 & 80 & 14.2 \\
7 & floors & 46.1 & 30 & 85 & 12.1 \\
8 & windows & 61.8 & 30 & 90 & 13.2 \\
9 & doors & 49.8 & 20 & 80 & 11.0 \\
10 & water installations & 34.1 & 20 & 100 & 12.5 \\
11 & sewage installations & 35.1 & 20 & 100 & 12.5 \\
12 & heating installations & 37.6 & 20 & 100 & 14.6 \\
13 & internal plasters & 39.1 & 20 & 75 & 9.9 \\
14 & external plasters & 49.7 & 20 & 100 & 16.3 \\ \hline \end{tabular}
\end{table} 
Table 8: Average technical wear and tear for the components of the buildings tested. Assuming the division of building elements into order groups, it is possible to assess the size of rehabilitation needs. It is proposed to adopt 4 order groups of elements:  
* elements for which rehabilitation is absolutely necessary, with sequence values greater than 0.068,
* elements for which rehabilitation is important, with values of order indicators from 0.051 to 0.068,
* elements for which rehabilitation is useful, with values of order indicators from 0.031 to 0.05,
* elements for which rehabilitation is not needed now, with sequence index values less than 0.031. The first two groups include buildings elements which technical wear is greater than 50%. Additionally, rehabilitation is absolutely recommended for them due to the cultural and historical values of the buildings themselves or their location. The \"rehabilitation is useful\" group contains elements with the degree of wear lower than 50%, but due to their location and cultural conditions, their (or their elements) rehabilitation must be performed earlier than the repair for the elements of the fourth group. Assuming the division of the buildings into the four groups, it is possible to assess the size of the rehabilitation needs for the analyzed group of buildings.