Author Contributions
Conceptualization, F.B., E.G., A.G. and M.-A.S.; methodology, F.B., E.G., A.G. and M.-A.S.; software, F.B., E.G. and A.G.; formal analysis, F.B., investigation, F.B. and E.G.; writing—original draft preparation, F.B. and E.G.; writing—review and editing, F.B., E.G. and A.G.; supervision, M.-A.S.; project administration, A.G. and M.-A.S. All authors have read and agreed to the published version of the manuscript.
Figure 1.
Geometry of the model of the reference building.
Figure 1.
Geometry of the model of the reference building.
Figure 2.
Schedules used for space heating and natural ventilation during the heating season, according to the climate zones established by the Italian regulation.
Figure 2.
Schedules used for space heating and natural ventilation during the heating season, according to the climate zones established by the Italian regulation.
Figure 3.
Summary of climate data for Italy.
Figure 3.
Summary of climate data for Italy.
Figure 4.
Graphic legend of the chromatic scale described in
Table 4.
Figure 4.
Graphic legend of the chromatic scale described in
Table 4.
Figure 5.
Solar radiation absorbed by the envelope element. HR and LR refer to “High Reflectance” and “Low Reflectance”, respectively.
Figure 5.
Solar radiation absorbed by the envelope element. HR and LR refer to “High Reflectance” and “Low Reflectance”, respectively.
Figure 6.
External surface temperature of the envelope element. HR and LR refer to “High Reflectance” and “Low Reflectance”, respectively.
Figure 6.
External surface temperature of the envelope element. HR and LR refer to “High Reflectance” and “Low Reflectance”, respectively.
Figure 7.
Convective heat transfer between the envelope element and the neighbouring thermal zone. HR and LR refer to “High Reflectance” and “Low Reflectance”, respectively.
Figure 7.
Convective heat transfer between the envelope element and the neighbouring thermal zone. HR and LR refer to “High Reflectance” and “Low Reflectance”, respectively.
Figure 8.
Heating and cooling demand for the relevant thermal zone. HR and LR refer to “High Reflectance” and “Low Reflectance”, respectively.
Figure 8.
Heating and cooling demand for the relevant thermal zone. HR and LR refer to “High Reflectance” and “Low Reflectance”, respectively.
Figure 9.
Yearly effect of the use of reflective materials for 75 locations in Italy. (a) Savings versus WCZ. (b) Savings versus yearly average temperature.
Figure 9.
Yearly effect of the use of reflective materials for 75 locations in Italy. (a) Savings versus WCZ. (b) Savings versus yearly average temperature.
Figure 10.
Day-by-day and cumulative energy balance for space heating, Bologna.
Figure 10.
Day-by-day and cumulative energy balance for space heating, Bologna.
Figure 11.
Day-by-day and cumulative energy balance for space heating, Palermo.
Figure 11.
Day-by-day and cumulative energy balance for space heating, Palermo.
Figure 12.
Predicted net effect of the use of reflective materials against simulated values. Different plots represent the different building types. Results are shown for the case of flat roof.
Figure 12.
Predicted net effect of the use of reflective materials against simulated values. Different plots represent the different building types. Results are shown for the case of flat roof.
Figure 13.
Results of the application of the linear regression: net effect of reflective materials on primary energy use against the WCZ for different building types.
Figure 13.
Results of the application of the linear regression: net effect of reflective materials on primary energy use against the WCZ for different building types.
Figure 14.
Results of the application of the linear regression: net effect of reflective materials on primary energy use against the WCZ for different building types.
Figure 14.
Results of the application of the linear regression: net effect of reflective materials on primary energy use against the WCZ for different building types.
Figure 15.
Maps showing the results extrapolated to the Italian territory, in case of building model with flat roof in current climate conditions. The colour code used in these maps was defined in
Figure 4 and
Table 4.
Figure 15.
Maps showing the results extrapolated to the Italian territory, in case of building model with flat roof in current climate conditions. The colour code used in these maps was defined in
Figure 4 and
Table 4.
Figure 16.
Local climatic variables versus yearly average temperature.
Figure 16.
Local climatic variables versus yearly average temperature.
Figure 17.
Maps showing the results extrapolated to the Italian territory for a building model with flat roof, in case of 1 °C warmer climate conditions. The colour code used in these maps was defined in
Figure 4 and
Table 4.
Figure 17.
Maps showing the results extrapolated to the Italian territory for a building model with flat roof, in case of 1 °C warmer climate conditions. The colour code used in these maps was defined in
Figure 4 and
Table 4.
Table 1.
Construction features of the building envelope components of the reference building. Note that the symbols d, , , R, U, and c represent, respectively, thickness, thermal conductivity, density, thermal resistance, thermal transmittance, and specific heat capacity.
Table 1.
Construction features of the building envelope components of the reference building. Note that the symbols d, , , R, U, and c represent, respectively, thickness, thermal conductivity, density, thermal resistance, thermal transmittance, and specific heat capacity.
Material | d
|
|
| R
| U
| c
|
---|
Outer walls (type MLP03 from UNI/TR 11552) |
Plaster—outer | 0.02 | 0.90 | 1800 | 0.029 | 35.0 | 1000 |
Semi-hollow bricks | 0.25 | 0.40 | 1000 | 0.625 | 1.6 | 1000 |
Plaster—inner | 0.02 | 0.70 | 1400 | 0.029 | 35.0 | 1000 |
Roof (type COP04 from UNI/TR 11552) |
Clinker | 0.03 | 0.70 | 1500 | 0.043 | 23.3 | 1000 |
Bituminous membrane | 0.01 | 0.17 | 1200 | 0.059 | 17.0 | 1000 |
Screed | 0.06 | 1.06 | 2000 | 0.057 | 17.7 | 1000 |
Brick concrete slab | 0.22 | 0.67 | 1270 | 0.330 | 3.0 | 1000 |
Plaster—inner | 0.02 | 0.70 | 1400 | 0.029 | 35.0 | 1000 |
Inner floor (type SOL05 from UNI/TR 11552) |
Stoneware | 0.015 | 1.47 | 1700 | 0.010 | 98.0 | 1000 |
Cement mortar | 0.02 | 1.40 | 2000 | 0.014 | 70.0 | 1000 |
Screed | 0.06 | 1.06 | 1700 | 0.019 | 53.0 | 1000 |
Brick concrete slab | 0.22 | 0.67 | 1270 | 0.33 | 3.0 | 1000 |
Plaster—inner | 0.02 | 0.70 | 1400 | 0.029 | 35.0 | 1000 |
Inner partition walls |
Plaster—inner | 0.02 | 0.70 | 1400 | 0.029 | 35.0 | 1000 |
Hollow bricks | 0.12 | 0.39 | 610 | 0.31 | 2.5 | 1000 |
Plaster—inner | 0.02 | 0.70 | 1400 | 0.029 | 35.0 | 1000 |
Ground floor |
Stoneware | 0.015 | 1.47 | 1700 | 0.010 | 98.0 | 1000 |
Cement mortar | 0.02 | 1.40 | 2000 | 0.014 | 70.0 | 1000 |
Screed | 0.06 | 1.06 | 1700 | 0.019 | 53.0 | 1000 |
Brick concrete slab | 0.22 | 0.67 | 1270 | 0.33 | 3.0 | 1000 |
Table 2.
Summary of coefficients used for the calculation of the efficiency of the energy conversion units in the buildings.
Table 2.
Summary of coefficients used for the calculation of the efficiency of the energy conversion units in the buildings.
Eq. n. | Coefficients |
---|
1 | |
|
|
3 | |
4 |
|
5 | |
Table 3.
Model characteristics varied through a one-parameter-at-a-time approach, compared to the corresponding values in the reference building model. Note that surrounding buildings in the non-reference simulations are located at a distance of 12 m from the modelled building.
Table 3.
Model characteristics varied through a one-parameter-at-a-time approach, compared to the corresponding values in the reference building model. Note that surrounding buildings in the non-reference simulations are located at a distance of 12 m from the modelled building.
Parameter | Value in Reference Model | Variations |
---|
Building orientation [degree] | 0 | 45, 90, 135, 180, 225, 270, 315 |
Number of storeys | 6 | 3, 4, 5 |
Past energy upgrade measures | 1970s type | Renovation1, Renovation2 |
Height of surrounding buildings [m] | 0 | 15, 21 |
Schedule of heating setpoint [°C] | 20 | 19, 21 |
Schedule of cooling setpoint [°C] | 26 | 25, 27 |
Table 4.
Legend of the chromatic scale set to develop thematic maps representing the effects of high-reflective roof coverings on the energy demand of the reference building.
Table 4.
Legend of the chromatic scale set to develop thematic maps representing the effects of high-reflective roof coverings on the energy demand of the reference building.
Colour | Meaning |
---|
Green | The entire prediction interval corresponds to a reduction in annual primary energy demand for heating and cooling. |
Light Green | Part of the prediction interval corresponds to an increase in annual primary energy demand for heating and cooling, but the entire confidence interval is in the field of reduction in energy demand. High-reflective roof is likely to reduce annual energy consumption. |
Yellow | Both intervals (prediction and confidence) are divided between the fields of energy reduction and energy increase. It is not possible to expect positive or negative effects from the application of high reflective materials on the building roof, if the specific conditions of the real building are not considered. |
Orange | Part of the prediction interval corresponds to a reduction in annual primary energy demand for heating and cooling, but the entire confidence interval is in the field of increased energy demand. High-reflective roof is likely to increase annual energy consumption. |
Red | The entire prediction interval corresponds to an increase in annual primary energy demand for heating and cooling. |
Table 5.
Analysis of the regression using the reference dataset (* = p ≤ 0.05; *** = p ≤ 0.001).
Table 5.
Analysis of the regression using the reference dataset (* = p ≤ 0.05; *** = p ≤ 0.001).
Model | R | p (HDD) | p (SCV) | p (HDD·SCV) |
---|
HDD | 0.82 | *** | - | - |
SCV | 0.66 | - | *** | - |
HDD + SCV | 0.83 | *** | * | - |
HDD + SCV + HDD·SCV | 0.83 | | | |
Table 6.
Regression coefficients of the multi-linear regression between the net effect of high-reflective surfaces and the selected building-related parameters.
Table 6.
Regression coefficients of the multi-linear regression between the net effect of high-reflective surfaces and the selected building-related parameters.
| |
---|
Past energy upgrade measures | 1.38 |
Number of storeys | 0.02 |
Building orientation | 0.01 |
Height of surrounding buildings | 0.01 |
Roof tilt | 0.15 |
Table 7.
Final regression coefficients for the effect of the use of reflective materials on roofs.
Table 7.
Final regression coefficients for the effect of the use of reflective materials on roofs.
Roof Pitch | BT | | | | R |
---|
Flat roof | OLD | 0.362 | 1.84 | −0.319 | 0.85 |
REN1 | 0.377 | 1.64 | −0.333 | 0.86 |
REN2 | 0.131 | 2.98 | −0.109 | 0.91 |
Pitched roof | OLD | 0.390 | 1.88 | −0.333 | 0.85 |
REN1 | 0.382 | 1.70 | −0.336 | 0.86 |
REN2 | 0.140 | 3.06 | −0.114 | 0.90 |
Table 8.
Summary of the results for current climate conditions, separated for climate zone, roof tilt, and building type. The values indicate the share of the municipalities for which the colour is light green or green.
Table 8.
Summary of the results for current climate conditions, separated for climate zone, roof tilt, and building type. The values indicate the share of the municipalities for which the colour is light green or green.
| Flat Roof | Pitched Roof |
---|
| OLD | REN1 | REN2 | OLD | REN1 | REN2 |
A | 100% | 100% | 100% | 100% | 100% | 100% |
B | 99% | 99% | 100% | 99% | 99% | 99% |
C | 57% | 74% | 99% | 52% | 67% | 99% |
D | 0% | 0% | 53% | 0% | 0% | 48% |
E | 0% | 0% | 0% | 0% | 0% | 0% |
F | 0% | 0% | 0% | 0% | 0% | 0% |
Tot | 9% | 11% | 25% | 9% | 10% | 24% |
Table 9.
Summary of the results for 1 °C warmer climate conditions, separated for climate zone, roof tilt, and building type. The values indicate the share of the municipalities for which the colour is light green or green.
Table 9.
Summary of the results for 1 °C warmer climate conditions, separated for climate zone, roof tilt, and building type. The values indicate the share of the municipalities for which the colour is light green or green.
| Flat Roof | Pitched Roof |
---|
| OLD | REN1 | REN2 | OLD | REN1 | REN2 |
A | 100% | 100% | 100% | 100% | 100% | 100% |
B | 100% | 99% | 100% | 100% | 99% | 99% |
C | 96% | 97% | 100% | 94% | 96% | 100% |
D | 10% | 21% | 87% | 8% | 17% | 83% |
E | 0% | 5% | 0% | 0% | 0% | 3% |
F | 0% | 0% | 0% | 0% | 0% | 0% |
Tot | 16% | 18% | 34% | 15% | 17% | 33% |