Analysis of the school building structure

Based on the information on school building structure collected via the 95 energy questionnaires, it was found that the heat transfer coefficients of the structures varied in the different countries due to the difference in climatic zones, national regulations and requirement values. In most of the analysed schools, the thermal characteristics of the building structures were very poor. The heat transfer coefficients of the walls varied between 0.33 and 2.6 W/m2K, and typically between 1.0 and 2.0 W/m2K. In most cases, the walls were not heat insulated, which meant that the heat transfer coefficients were high. Schools in Slovakia had the lowest heat transfer coefficients for the walls, with a minimum value of 0.33 W/m2K and a maximum value of 0.82 W/m2K. Among the 95 analysed schools, the highest heat transfer coefficients for walls were found in Ukraine (1.6 to 2.6 W/m2K) and Serbia (1.6 to 2.45 W/m2K). There were big differences in the heat transfer coefficients between new/modernised buildings and old buildings. In one Hungarian school, for example, one of the walls in the new section of the building had a heat transfer coefficient of 0.40 W/m2K, while walls in the old section of the same school had a high heat transfer coefficient (U = 1.72 W/m2K).

Heat transfer coefficients for roofs varied from 0.22 to 4.21 W/m2K, and were typically between 0.6 and 1.2 W/m2K. Slovakia (0.47 to 0.85 W/m2K) and Albania (0.52 to 1.12 W/m2K) had the lowest values, while in Tajikistan (1.1 to 1.54 W/m2K) and Bosnia and Herzegovina (1.1 to 1.56 W/m2K) the heat transfer coefficients for roofs were significantly higher.

Heat transfer coefficients for windows varied from 1.1 to 5.8 W/m2K. Schools in Serbia (1.47 to 2.80 W/m2K) and Kazakhstan (1.1 to 2.4 W/m2K) had the lowest values, while schools in Albania (2.5 to 4.6 W/m2K) and Italy (3.1 to 5.8 W/m2K) had the highest heat transfer coefficients.

The average heat transfer coefficient and standard deviation for walls, roofs and windows were calculated based on the 95 questionnaires. The calculated average values were surface weighted (∑A*U/∑A). The average heat transfer coefficient for external walls is 1.28 W/m2K and for roofs 0.97 W/m2K. In the case of doors and windows

(Figure 36),

Distribution of heat transfer coefficients for windows and doors

the situation is slightly better, due to the fact that windows have already been replaced in several of the schools. The average heat transfer coefficient for windows is 2.57 W/m2K. The average values for heat transfer coefficients and standard deviations for walls, roofs, windows and doors are shown in

Figure 37.

Average heat transfer coefficients and standard deviations for the 95 analysed schools



The average heat transfer coefficients for the different countries are shown in

Figure 38.

Average heat transfer coefficients by country

 
Ministero Dell'ambiente Italian Trust Fund