Assessment of climate change mitigation and adaptation strategies at

the district scale

Marjorie Musy

Context

Urban Heat Islands (UHI) increase

They can have significant implications for building energy use and greenhouse gas emissions, comfort and indeed for mortality; as the influence of heat waves is intensified.

Solutions to climate change mitigation, energy transition and climate change adaptation must thus be tackled simultaneously.

Policymakers face an increasing need to improve knowledge of environmental impacts from city layouts and uses on the urban climate, in order to assist with planning climate change mitigation and adaptation measures.

< 0.75 °C

0.75 - 1 °C

1 - 1.5 °C

1.5 - 2 °C

2 - 3°C

> 3 °C

Surface d'eau2 kms

Îlot de chaleur urbain nocturne sur Nantes Métropole

Solutions Urban form, materials, nature (water & vegetation), use are Influencing parameters. Mitigation and adaptation actions have to consider and/or act on these parameters.

Assessment

The effectiveness of these solutions requires, in addition to knowledge of the relationships between climate and the thermal behaviour of buildings, the development of approaches that support predictions of energy use in the urban context and its impacts on the urban microclimate.

Illustration: The vegDUD Project « Role of vegetation in sustainable urban development »

Studied « object » ANR Villes durables 2009 ANR- 09-VILL-0007

Knowledge Characterization

Assessment of impacts in different contexts

Results

T surface

°C

27°C

17°C

T air

MRT

40°C

50°C

10°C Lawn

Gre

en

wal

l

UTCI : 24°C

Trees Lawns Buildings’envelop

Greenroofs

Greenwalls

Buildingtostreetscale(TRNSYS)

Directeffectsonbuildingenergydemand,amplifiedindenseurbancanyons

Streettodistrictscale(SOLENE-microclimat)

Higheffectforglazed&insulatedbuildings

Loweffectforglazedbuildings–nonforothers

Higheffectforthetopfloor,loweffecttheotherfloors

Higheffectfornoninsulatedbuildingsorinsulatedbuildingswithalowglazingratio

Districttocityscale(TEB)

Mediumeffect Loweffect

Higheffectifirrigated

Summer energy consumption and indoor comfort

Trees Lawns Buildings’envelop

Greenroofs

Greenwalls

Streettodistrictscale(SOLENE-microclimat)

Higheffect Loweffect Loweffect Mediumeffect,higherin

Districttocityscale(TEB)

Mediumeffect,higherifirrigated

Loweffect loweffect

Urban climate and outdoor comfort

Results Trees Lawns Buildings’envelop

Greenroofs Greenwalls

Buildingtostreetscale(TRNSYS)

Directeffectsonbuildingenergydemand,amplifiedin

denseurbancanyons

Streettodistrictscale(SOLENE-microclimat)

Higheffectforglazed&insulatedbuildings

Loweffectforglazed

buildings–nonforothers

Higheffectforthetopfloor,

loweffecttheotherfloors

Higheffectfornoninsulatedbuildingsor

insulatedbuildingswithalowglazingratio

Districttocityscale(TEB) Mediumeffect Loweffect Higheffectifirrigated

Summer energy consumption and indoor comfort

Trees Lawns Buildings’envelop

Greenroofs

Greenwalls

Streettodistrictscale(SOLENE-microclimat)

Higheffect Loweffect Loweffect Mediumeffect,higherin

Districttocityscale(TEB)

Mediumeffect,higherifirrigated

Loweffect loweffect

Urban climate and outdoor comfort

Conclusion

Vegetation is a good solution to climate adaptation but it won’t be able to compensate increasing anthropogenic heat loads due to densification (transportation, air cooling… )

However densely planted green spaces will offer cool islands in which people will have respiration spaces during heat waves.

Sustainable urban development require the composition of solutions (vegetation, water, cool materials…) added to a necessary effort to reduce heat gains in summer.

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