Cooling effect of street trees in Bristol

In cities the climate is significantly warmer than in the surrounding countryside. This is known as the Urban Heat island (UHI) effect.  The UHI effect is caused by a range of factors including hard building surfaces which absorb and radiate heat and the design of urban areas which means they have less ventilation compared to rural areas. 

The UHI effect can have negative impacts on human health, ranging from general discomfort to exhaustion, respiratory problems, and heat stroke.  There is concern because as our climate changes it is expected that the UHI effect will increase in severity due to rising temperatures.

Greenspace and trees may be able to help us reduce the UHI effect as greenspace with trees has been shown to reduce temperatures in areas local to those greenspaces.  However, the role of trees in urban areas in cooling air temperature needs to be better understood.  Specifically, we need more data, collected at a higher accuracy and from a wider range of urban situations.

In this experiment we will be trialling Internet of Things (IoT) technology to gather data about street trees.  Whilst IoT has the potential to deliver high quality data at a much lower cost, we specifically want to see how useful it will be at capturing data that will improve our knowledge of how trees in urban areas regulate the temperature of the surrounding area.  We also want to understand both the opportunities and barriers to the more widescale use of this technology for this purpose.

Bespoke sensors, using the latest technology, will be installed and monitor the micro-climate of two urban streets.  They will record information on air temperature, relative humidity, solar radiation, wind speed and wind direction.  As well as testing the sensors, it is hoped the data gathered will provide insights into the contribution of urban street trees to air cooling. The sensors are planned to be installed towards the end of July 2019 and will be in place for 2-3 months.