Table 1
L’Hospitalet de Llobregat monthly data of average maximum temperature, mean temperature, average minimum temperature, relative humidity and daily global horizontal radiation.
| MONTH | AVERAGE MAXIMUM TEMPERATURE (°C) | MEAN TEMPERATURE (°C) | AVERAGE MINIMUM TEMPERATURE (°C) | RELATIVE HUMIDITY (%) | DAILY GLOBAL HORIZONTAL RADIATION (kWH/m2) |
|---|---|---|---|---|---|
| January | 13.6 | 9.2 | 4.7 | 70% | 2.2 |
| February | 14.3 | 9.9 | 5.4 | 70% | 3.1 |
| March | 16.1 | 11.8 | 7.4 | 70% | 4.3 |
| April | 18.0 | 13.7 | 9.4 | 69% | 5.7 |
| May | 21.1 | 16.9 | 12.8 | 70% | 6.5 |
| June | 24.9 | 20.9 | 16.8 | 68% | 7.1 |
| July | 28.0 | 23.9 | 19.8 | 67% | 7.3 |
| August | 28.5 | 24.4 | 20.2 | 68% | 6.1 |
| September | 26.0 | 21.7 | 17.4 | 70% | 4.8 |
| October | 22.1 | 17.8 | 13.5 | 73% | 3.3 |
| November | 17.3 | 13.0 | 8.6 | 71% | 2.3 |
| December | 14.3 | 10.0 | 5.7 | 69% | 1.9 |
| Year | 20.4 | 16.1 | 11.8 | 70% | 4.6 |
[i] Source: AEMET (2024).
Figure 1
(A) Locations of the case studies and energy simulation domains (500 × 500 m each): sites of interest (4 ha each) for the simulations in Bellvitge (B1) and Gornal (C1); and aerial views of Bellvitge (B2) and Gornal (C2).
Note: Bellvitge’s urban form consists of 14-storey linear blocks (96 m long × 9–10 m wide), each containing dual 75 m2 apartments per floor, arranged in a parallel alignment with 40 m spacing. Interspersed low-rise buildings provide commercial and community services. In contrast, Gornal features 18-storey residential towers with four 100 m2 apartments per floor around a central core, complemented by vibrant ground-floor commercial spaces.
Source: Google Earth.
Figure 2
Urban form metrics for case studies (red dots) compared with other European social housing districts (black dots), compact urban fabrics (white dots) and historical urban fabrics (triangles).
Table 2
Urban form metrics of the case studies.
| A (m2) | C (m2) | F (m2) | V (m3) | L | GSI | FSI | OSR | TREE DENSITY (unit/ha) | GREEN SPACE INDEX | PERVIOUS SURFACE FRACTION | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| DEFINITION | DISTRICT REFERENCE AREA | BUILDING FOOTPRINT | GROSS FLOOR AREA | BUILT VOLUME | |||||||
| Bellvitge | 40,232 | 8,282 | 62,753 | 191,213 | 7.58 | 0.21 | 1.56 | 1.96 | 67 | 0.076 | 0.192 |
| Gornal | 40,232 | 7,573 | 65,639 | 203,267 | 8.67 | 0.19 | 1.63 | 2.01 | 83 | 0.103 | 0.013 |
[i] Note: FSI = floor space index; GSI = ground space index; OSR = open space ratios.
Table 3
Tree species within the investigated urban areas of Bellvitge and Gornal.
| SCIENTIFIC NAME | COUNT | % | LEAF TYPE | SIZE CLASS | MATURE HEIGHT (m) |
|---|---|---|---|---|---|
| Pinus pinea | 284 | 12.6% | Evergreen | High | 12–20 |
| Ulmus pumila | 255 | 11.3% | Deciduous | Medium | 10–15 |
| Platanus hispanica | 161 | 7.1% | Deciduous | High | 20–30 |
| Jacaranda mimosifolia | 150 | 6.6% | Semi-deciduous | Medium–high | 10–15 |
| Tipuana tipu | 150 | 6.6% | Deciduous | High | 12–18 |
| Celtis australis | 129 | 5.7% | Deciduous | Medium–high | 15–20 |
| Styphnolobium japonicum | 111 | 4.9% | Deciduous | Medium | 10–15 |
| Others | 1,021 | 45.1% | – | – | – |
| Total | 2,261 | 100% |
[i] Source: Ajuntament de l’Hospitalet de Llobegrat (2024): municipal tree inventory.
Figure 3
Overview of the SOlar LongWave Environmental Irradiance Geometry (SOLWEIG) model.
Note: DSM = digital surface model.
Source: Lindberg et al. (2019).
Figure 4
Climatic data used for simulations (3–9 August).
Source: Typical meteorological year (TMY) EnergyPlus Weather (EPW) from Climate.OneBuilding.Org (2024).
Figure 5
Maps of the average mean radiant temperatures (MRTs) obtained for Bellvitge and Gornal districts during the simulation period (3–9 August, 08:00–14:00 UTC) with and without trees.
Source: Lopez-Ordonez et al. (2024).
Table 4
Summary of the key mean radiant temperatures (MRT) of the study areas.
| MRT RANGE (°C) | BELLVITGE | GORNAL | ||
|---|---|---|---|---|
| WITHOUT TREES | WITH TREES | WITHOUT TREES | WITH TREES | |
| Maximum | 71.98 | 71.57 | 71.91 | 71.22 |
| Average | 55.23 | 49.95 | 57.44 | 48.57 |
| Minimum | 39.35 | 35.30 | 41.03 | 35.03 |
Figure 6
Percentage of open space according to its mean radiant temperature (MRT) for Bellvitge and Gornal districts during the simulation period (3–9 August, 08:00–14:00 UTC) with and without trees.
Source: Lopez-Ordonez et al. (2024).
Table 5
Summary of key mean radiant temperatures (MRTs) of the study area.
| MRT RANGE (ºC) | BELLVITGE | GORNAL | ||||||
|---|---|---|---|---|---|---|---|---|
| WITHOUT TREES | % | WITH TREES | % | WITHOUT TREES | % | WITH TREES | % | |
| 35–40 | 2 | 0.006 | 313 | 0.97 | 0 | 0 | 2,558 | 7.71 |
| 40–45 | 4,358 | 13.53 | 8,135 | 25.26 | 22 | 0.07 | 6,524 | 19.67 |
| 45–50 | 2,569 | 7.98 | 6,815 | 21.16 | 2,060 | 6.21 | 7,987 | 24.08 |
| 50–55 | 3,993 | 12.40 | 6,353 | 19.73 | 5,972 | 18 | 7,325 | 22.08 |
| 55–60 | 6,121 | 19.01 | 5,516 | 17.13 | 13,586 | 40.96 | 5,858 | 17.66 |
| 60–65 | 11,428 | 35.49 | 3,851 | 11.96 | 10,231 | 30.85 | 2,649 | 7.99 |
| 65–70 | 3,491 | 10.84 | 1,105 | 3.43 | 1,283 | 3.87 | 267 | 0.80 |
| 70–75 | 239 | 0.74 | 113 | 0.35 | 15 | 0.05 | 1 | 0.003 |
[i] Note: Yellow = moderate, pink = strong and purple = very strong heat stress levels.
Figure 7
Hourly evolution of the mean radiant temperature (MRT) distribution (maximum, minimum and quartiles) compared with the average distribution of MRT throughout the simulation period for Bellvitge and Gornal districts with and without trees.
Figure 8
Hourly evolution of the mean radiant temperature (MRT) maps for the Gornal case, with and without trees (UTC time).
Figure 9
Correlation between mean radiant temperature (MRT) and universal thermal climate index (UTCI) values.
Figure 10
Distribution of open space area by thermal comfort perception level according to the universal thermal climate index (UTCI) scale (based on the average results during the simulation period 3–9 August, 08:00–14:00 UTC).
Figure 11
Application of mean radiant temperature (MRT) thresholds for urban green infrastructure planning to mitigate heat stress: example based on the Bellvitge case study (11:00 UTC).
Note: (left) The map depicts results without trees and allows for detecting hotspots and identifying critical shade providers (e.g. those out of yellow areas). (right) The map depicts results with trees and helps ranking trees based on their rank cooling effectiveness.