Mitigation Strategies Assessment Using ENVI-MET

Using climate modelling techniques, strategies for improving outdoor thermal comfort (OTC) were assessed specifically for green- and brown-fields in Singapore. In collaboration with two Singaporean Agencies, Urban Redevelopment Authority (URA) and Housing Development Board (HDB), the Cooling Singapore team designed and modelled several specific strategy scenarios for test areas in the Jurong Lake District, in the Central Business District and in an HDB estate in Punggol. These scenarios were composed by measures including vegetation, urban geometry and surface materials, aiming to improve the wind flows and reduce heat storage. Using micro-scale computational fluid dynamics (ENVI-met model) the team was able to study the thermal environment under different annual meteorological conditions at the building and neighbourhood scale. The team conducted a spatio-temporal analysis that included a sensitivity analysis as well as a thermal comfort exposure mapping for each specific test area. Specific climate-responsive planning guidelines with quantitive and qualitative recommendations will be developed.

 Source: Lea Reufenacht  Top (left to right): Increase setbacks on ground floor from 4 to 9 meters; Re-arrange and re-orientate punctual buildings blocks; Adjust height, location and form of C-walk. Bottom (left to right): Increase number of trees (33% and 60%); Install large-scale urban canopy/pergola to increase shading; Retrofit pavement and façade materials with green facades and retro-reflective materials at different heights.

Source: Lea Reufenacht

Top (left to right): Increase setbacks on ground floor from 4 to 9 meters; Re-arrange and re-orientate punctual buildings blocks; Adjust height, location and form of C-walk.
Bottom (left to right): Increase number of trees (33% and 60%); Install large-scale urban canopy/pergola to increase shading; Retrofit pavement and façade materials with green facades and retro-reflective materials at different heights.

Some of the results for Singapore are:

  • It is relevant to use reference weather types to analyze OTC throughout the year

  • Porosity and increasing ventilation can improve OTC in courtyards and open areas

  • Green facades can only have an impact on OTC in areas very close to them (< 2 - 4 m). Orientation of the facade affects significantly its outdoor thermal performance.

  • Green roofs have little impact on OTC, if applied only locally.

  • Shadowing of trees might not be sufficient to attain an acceptable OTC level in low wind conditions (during midday and afternoon).

  • Void deck can improve ventilation and thermal comfort levels in outdoor spaces (e.g. courtyards).

  • New developments can increase one category the thermal comfort level (e.g. from warm to hot) in already existing developments


Meso-scale UHI Simulations

The Weather Research and Forecasting (WRF) model was used to analyze the impact of UHI for April 2016 (the inter-monsoon season) when the UHI intensity in Singapore is expected to be at its highest. The key findings for Singapore include that the UHI effect can be as high as 4.2ºC during night time. The mitigation measures evaluated through WRF suggest that:

  1. Using high reflective materials for roofs can lower the temperatures by about 1.47ºC

  2. A 20 % reduction in energy can be achieved by increasing the thermostat set temperature in commercial buildings by 4ºC.

  3. Increasing building density can adversely affect ventilation and thermal comfort, and blockage of major breezeways should hence be avoided for developments planned for 2030.

WRF modelling and simulations can support the mitigation of UHI and help propose countermeasures to offset the impact of UHI in Singapore.  The impact of UHI is of particular interest to urban development for existing and future developments. Further improvements in the modelling effort are currently underway and will help to develop a strong UHI mitigation framework.


This video is an overview of the simulations created by Cooling Singapore since its inception in 2017. These include simulations of the UHI effect in Singapore, heat rejection from buildings, and heat related from road traffic. It also includes a visualisation of the mitigation strategy analysis done for the Punggol HDB estate case study. The video was created in Singapore Views, a software developed in-house by CIVAL, demonstrating its capacity to visualise spatial data in Singapore.