Impact on outdoor spaces

Outdoor spaces are defined as the areas outside our houses and buildings: public and private spaces. These include the areas in which we engage in leisure activities, seek to cool off, and enjoy Nature, such as forests, beaches, parks, and (our own) gardens. They also comprise paved spaces, such as bicycle routes, roads, shopping streets, pavement cafés, plazas, and industrial estates. Heat issues primarily occur in paved areas. The paragraphs below explain the problems that heat can cause in outdoor spaces, and the page on  measures to combat heat provides information to address these problems.

Heat issues in outdoor spaces

According to the Heat-proof Cities study conducted by Amsterdam UAS, outdoor heat issues depend on two different types of temperature: ambient temperature and perceived or apparent temperature.

• High ambient temperatures in an entire city during prolonged heat result in, e.g., warm nights, which prevent many people from getting a good night’s sleep. Due to the heat island effect, cities retain their high ambient temperature for a longer period of time than outlying areas.
• A high perceived temperature can cause heat stress. The perceived temperature can differ sharply locally and from one person to the next. In a car park directly exposed to the sun, for example, the temperature can be perceived as 10 to 15 degrees higher than in the shade of a tree. The perceived temperature depends on several factors, such as ambient temperature, humidity, ventilation, and heat radiation. Many maps use the PET [physiological equivalent temperature] value to express the perceived temperature. PET is defined as the average perceived temperature on a hot summer day, between noon and 6 PM.

The Guidelines for Standardised Stress Tests help to identify heat issues

Many types of heat maps can visualise the heat issues affecting an area. Visualising the heat issues in an area is included in the mandatory climate stress test to be conducted by municipal and other government authorities. The Guidelines for Standardised Stress Tests developed under the Delta Plan for Spatial Adaptation can help to determine which heat maps are most appropriate for your situation. These Guidelines refer to several heat maps and their map narratives in the Climate Impact Atlas. These will help you to gain insight into the heat issues in an area.

Neighbourhood Dashboard helps to gain insight into heat issues by neighbourhood

Another useful tool is the Neighbourhood Dashboard [in Dutch] in the Climate Impact Atlas. It provides several maps you can use to better understand heat issues in a neighbourhood:

• The Heat Map – Perceived Temperature: this map shows the perceived temperature during an extremely hot summer afternoon for every place in the Netherlands, for now and for 2050.
• Maps showing how much shade there is on walking and cycling paths: here you can find the average shade percentage for walking and cycling paths per neighbourhood, and for each walking or cycling path separately. You can also see whether the shade is mainly produced by trees or by buildings.
• Maps on heat in relation to social vulnerability: one of these maps shows by neighbourhood the average percentage of over-65s in “poor health”. Furthermore, there is a map showing the percentage of households per neighbourhood living around or below the social minimum. This group is also particularly vulnerable to heat.

Other useful maps from the Climate Impact Atlas

The Climate Impact Atlas also features other maps that provide insight into heat issues in your area:

• The Distance to Cooling map: this map shows which municipal buildings are located at a maximum of 300 metres from a cool spot.
• The map Heat Stress Caused by Warm Nights: this map shows the average number of tropical nights per year in different urban areas in the Netherlands. Night heat is particularly an issue in urban areas, as a result of the urban heat island effect. Urban areas are often significantly warmer than the surrounding rural areas, especially at night, due to the slow release of heat from urban materials.