Greener & Cooler. Thermal comfort as ecosystem service in the urban forest of Florence, Italy

Transcription

1 . Thermal comfort as ecosystem service in the urban forest of Florence, Italy Fabio Salbitano, Andrea Bettarini, Francesca Bottalico, Cristiano Foderi, Alessio Pratesi, Davide Travaglini

2 Introduction 1 Good Health, according to WHO, is a state of complete physical, social and mental well being An impressive number of studies on human health and urban trees/forest Very few on the relationships between trees/forest and thermal comfort N. of Documents on Human Health and Urban Forest (Scopus search)

3 Introduction 2 Thermal comfort : that condition of mind which expresses satisfaction with the thermal environment and is assessed by subjective evaluation (ANSI/ASHRAE Standard ) Human thermal comfort: a combination of a subjective sensation (how we feel) and objective interaction with the environment (heat and mass transfer rates). The six factors affecting thermal comfort are both environmental and personal

4 Introduction 3 Florence, Heat Risk Map Courtesy: CNR-Ibimet

5 Introduction 4 Temperature Trends Courtesy: LAMMA, Tuscany Source

6 Research Questions 1

7 Research Questions 2 Can we quantify the capacity of urban forest canopies mitigate the summer heat? Which is the confidence of rapid surveys approach? Can we define thresholds in performing various activities in urban forests under heat stress inducing conditions (clothing, type of activity, weather factors)? Are empyrical indices (T and RH-based) reliable and accurate in setting thresholds for heat risk alert programmes (e.g. app for thermal comfort calculations)? How do the activities carried out in the urban forest match with the perception of (thermal) comfort/discomfort as reported by users?

8 Where? When? What? SITE DATE COVER Cascine Park 1 25 AUG 75% Cascine Park 2 25 AUG 60% Cascine Park 3 29 AUG 75% Bobolino 27AUG 50% Boboli 27 AUG 55% Sorgane woodland 31 AUG 70% Villa Strozzi Park 28 AUG 60% Villa Fabbricotti Park 26 AUG 55% Villa Fabbricotti Park 1 SEPT 65% San Donato Park 2 SEPT 5% * * Comparison Pervious/Impervious

9 Where? When? What? INTERVIEWS MAPPING AND OBSERVING PEOPLE ACTIVITIES WEATHER DATA Temperature Humidity Wind Solar Radiation MICROCLIMATE measurements (WBGT)

10 What? How? Continuous measurement (8:00 a.m. to 8:00 p.m.) of meteorological parameters under tree cover (1) and full sun (2). DeltaOhmHD32.2 WET BULB GLOBETHERMOMETER WBGT Index Microclimatic parameters under canopy cover 60 min measurements (30 sec. interval 8:00 to 10:30 a.m. 1:00 to 3:00 p.m. 5:30 to 8:00 p.m. Weather Station PCE-FWS 20

11 How? Comparison of thermal comfort as estimated by Bioclimatic indices Summer Simmer Index SSI = 1.98 (T - ( (RH)) (T 58)) Humidex Index H = T + ( (0.06 RH T - 10)) T= air temperature; RH= Relative Humidity; Microclimatic Index WBGT (Wet Bulb Globe Temperature (Standard, ISO 7243) and algorithms for clothing and activities

12 How? Humidex chart

13 How? DeltaLog10_1 Clothing module

14 How? DeltaLog10_2 Activity module

15 Results_1...they provide shade, beauty, and privacy (introduction to EFUF 2016)

16 Results_2 Jogging,sport physical axcercise Dog walking Relaxing Walking Children activities Cycling

17 T SOR RH SOR1 Results_3

18 Results_4 T S.DON RH S.DON

19 Results_5

20 Results_6 Humidex: Cas1, Cas2, Sor1, Fabbr1 Bob1, Bob2, Str1,Fabbr2 Canopy Values always < 35 No Discomfort Values always < 40 Caution Full Sun Values > 40 Caution Values > 45 High Discomfort Summer Simmer Cas1, Cas2 Bob1, Bob2, Sor1, Str1, Fabbr2 Values < 100 Warm (low) Values < 105 Warm (average) Values > 105 High Discomfort Values > 112 Heat risk

21 Results_7 RELAX (1 met) SLOW WALKING (2,41 met) FAST WALKING (3,44 met) TOURIST CYCLING (3,5 met) SPORT CYCLING (5,7 met) RUNNING (8,34 met) GARDENING (2,62 met) Sport clothing (0,25 clo) 20 (acclim. 25) 20 (acclim. 25) MALE FEMALE MALE FEMALE GARDENER #1 #1 #2 #2 (1,1 clo) (0,3 clo) (0,45 clo) (0,6 clo) (0,7 clo) 32 (acclim. 33) 32 (acclim. 33) 32 (acclim. 33) 32 (acclim.33) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28) 26 (acclim. 28)

22 Results_7 bis

23 Results_8 Site Date Time Period WBGT avg value Morning 21,2 Cas1 25 AUG Half day 22,1 Late Afternoon 20,2 Morning 22,1 Cas2 25 AUG Half day 23,2 Late Afternoon 20,0 Morning 20,1 Cas3 29 AUG Half day 25,4 Late Afternoon 24,7 Morning 18,9 Bob1 27 AUG Half day 24,5 Late Afternoon 24,3 Morning 21,6 Bob2 27 AUG Half day 23,8 Late Afternoon 23,7 WBGT avg value Morning 20,1 Site Date Time Period Sor1 31 AUG Half day 22,8 Late Afternoon 23,3 Morning 20,5 Str1 28 AUG Half day 23,8 Late Afternoon 24,1 Morning 17,1 Fabbr1 26 AUG Half day 23,3 Late Afternoon 23,2 Morning 19,2 Fabbr2 1 SEPT Half day 23,7 Late Afternoon 22,9 Morning 21,4 S.Don 2 SEPT Half day 26,0 Late Afternoon 23,6 WBGT Index 23

24 Conclusions

25 Conclusions 1. Urban Forest canopies: good capacity in mitigating extreme summer heat. This is true also in the hottest hours of summer days: SHADE WORKS! (Captain Obvious 1); 2. Urban Forest in PERI-URBAN and HILLY location: BEST PERFORMANCES (Captain Obvious 2); 3. In the case of San Donato Park, where the canopy cover is still very low, the zones with pervious soils have a better performance as compared to the impervious ones; 4. Leisure activities UNDER CANOPY: NO THERMAL DISCOMFORT or heat associated risk, even during the hottest hours of the day. LIGHT SUMMER CLOTHING (Captain Obvious 3?); 5. LOW-MEDIUM FATIGUE WORKS ARE OK, if they do not require heavy equipment and clothing (Captain Obvious 4); 6. Bioclimatic indices tend to OVERESTIMATE the heat risk conditions. SSI seems to have a BETTER PERFORMANCE in discriminating the potential heat stress risk.

26 Conclusions 7. Interviews confirmed that the THERMAL COMFORT WAS PERCEIVED AS DECISIVELY HIGHER under tree cover; 8. The MANAGED URBAN FORESTS ARE FELT AS MORE COMFORTABLE (here the well being is greater); 9. The users consider Florence urban forests as "RELAXING" places, COOLER when compared to the neighborhoods where they live; 10. Activity mapping is a good method to cross-check both the weather data and the interview findings

27 We come from the shade and we need to go under the shade Thank you! 27