Climate Responsive Urbanism

2019 was the year when the world woke up to the prospect of climate change. It is fitting that the first event of 2020 was the launch of the year-long programme on Climate Responsive Urbanism, staged jointly by the UDG and the Edge Debate. The aim is to have by the end of the year, a clear idea of how to manage the urban climate.

Keynote speaker Gerald Mills of University College Dublin (as shown) introduced the Köppen climate classification scheme:

He warned that climate change will move type C climates towards type A, raising concerns including:

• Heat wave events. Humans have difficulty in adjusting to short-term changes in temperature. However, more people die of cold than of heat. 
• More intense rainfall, and
• Rising sea levels which he considered to be the key driving force for adaptation.

Turning to local climates, Gerald outlined how urbanisation changes the atmosphere, hydrology and biosphere. He identified three specific areas where urban areas differ from rural areas, and bring about the urban heat island effect:

1. The fabric of the city – impervious roofs and paved surfaces shed water rapidly but also greatly reduce the potential for evaporation and cooling. The hard surfaces break the connection between soil and atmosphere.
2. The unchanging city – while the rural environment changes its properties with the seasons (leaves) and rainfall events (the saturation and drying of soils), the urban environment changes relatively little.
3. The geometry of the city – tall buildings and canyon streets control access to wind, sunshine and sky.

In simple terms, the sun heats up surfaces during the day, while at night surfaces lose heat to passing air currents and by radiating thermal infrared radiation into the sky. In general, the greener the area, the lower is the urban heat island effect. In leafy suburban areas where the trees are allowed to grow bigger than the buildings, the local urban heat island effect may be relatively small. Different buildings have different needs. Modern office buildings want visible light but not full sunshine and the heat that it brings, and so many office buildings produce excess heat which they need to lose. Useful actions included:

• Change the albedo (the ability of an area to reflect light) including painting roofs white, and urban greening. However, changes at roof level may be less valuable than action at ground level where people spend time. The entire urban environment needs to be considered: it is no use having a white roof supermarket surrounded by large black-topped car parks.
• Plant trees: they connect the soil and atmosphere, which green building façades do not.
• Develop a common language: currently air quality specialists, building engineers, climate scientists, designers and planners do not use a common language.
• Circulate knowledge: this is not happening at the moment.
• Reduce traffic noise in order to allow people to leave their windows open, the most energy efficient form of cooling.

Marielena Nikolopoulou of the University of Kent added more detail on the impact of the form, height and massing of buildings. Research has identified urban forms that present higher irradiance values in winter and lower values in summer. Pedestrian wind comfort is influenced by building heights and street ratios.

The variability of how humans experience climate should be considered. The temperatures that people say are neither too cold nor too hot vary with the seasons, according to their expectations, their experience of air conditioning, and their social background. The climate strongly influences people’s use of outdoor spaces. In Mediterranean climates, public spaces are popular around midday in the winter, whereas in the summer, it is the coolness of the evening that attracts people. The searing heat of the midday summer sun can lead to deserted public spaces.

Nicola Bacon of Social Life introduced the idea of social sustainability, an appeal to place people at the heart of what is done, rather than treat them as an adjunct. Social sustainability combines the design of the physical realm with design of the social world in four elements: infrastructure to support social and cultural life; social amenities; systems for citizen engagement; and, space for people to evolve and grow.

Rachel Toms of Public Health England (PHE) raised the issue of health inequalities and how the less well-off are liable to be the least able to deal with climate effects. The impact of air pollution and heat are obvious concerns, but there are others, including stress and mental well-being. People who have been flooded are approximately six to seven times more likely to have depression, anxiety or post-traumatic stress disorder a year later. PHE advocates multi-disciplinary collaboration between public health, healthcare, built environment and climate change professionals at all levels and in all sectors, from policy and strategy to ‘on the ground action’, and adopting a whole systems approach to tackling climate change.

The systems approach was echoed by Asif Din of Perkins + Will who gave a presentation on BS67000 and City Resilience. The response to climate change requires leadership, organisation and action, rather than policies and press releases. Both central and local government should use BS67000 and if necessary, implement the ISO 9000/9001 Quality Management process to ensure that their systems are robust and responsive, that they are effectively led, and that their practices are up-to-date. Things clearly need to change.

Robert Huxford, Director UDG