Designing outdoor spaces with climate change in mind

The consequences of climate change are showing. Temperature records are breaking annually, weather systems are growing in intensity, and sea levels are rising. In the face of a more extreme climate, projects must be designed with the future in mind.

Many existing structures are at risk due to the effects of climate change, and if approaches to design do not change, new structures will be too. In this document, we will cover the forecasted changes in weather, how those changes will affect outdoor design, and what new strategies can be used to ensure new outdoor spaces endure the evolving climate conditions.

The expected consequences of climate change

In short, droughts and floods. Though two seemingly opposing extremes, the number of droughts and floods will surge as a result of an increasingly warm atmosphere. As the temperature of the atmosphere increases, the moisture content in the atmosphere increases with it. The problem is that the moisture content capacity of the atmosphere is rising at a faster rate than evaporation. The difference in the speed of these two processes means that the natural water cycle is taking longer to recharge, resulting in prolonged dry spells that are followed by intense rainfall.

How is outdoor design changing?

Managing two extremes requires two types of solution. Here we will take a look at the new methods being used to tackle droughts and floods.

Droughts

The main considerations for outdoor spaces during a drought are irrigation, temperature and shade.

Irrigation

Ensuring plants receive the right amount of water during a dry spell requires regular watering, which can problematic if hosepipe bans are imposed.

Installing tanks, water butts and other forms of water capture is an obvious route to take. ‘Grey water’ can also be considered. Recycled from baths, sinks and washing machines, ‘grey water’ is pumped into the garden, helping plants to survive. Intelligent planting also helps in this regard, as a changing climate means that some plants will not survive where they once would have done.

Temperature

Urban locations are warmer than rural ones, a result of the ‘urban heat island’ phenomenon. Urban spaces radiate more heat through buildings and machinery, creating an environment that is distinctly warmer than the surrounding areas. The University of Manchester conducted a study that showed the presence of more greenery and water drastically cooled the spaces around it. Including more plants within outdoor areas, be it in traditional borders or in-wall trellises, will have a cooling effect. Water features also help in this regard, although maintaining a source of water during extended dry spells might be a challenge.

Shade

Shade will become an essential part of outdoor spaces. As temperatures increase, the practicality of spaces like patios and dining areas will be reduced if no shade is provided, as surfaces become too hot to use. Shade can be provided through the use of pergolas, retractable roofs, trees and screens. When integrating shading into an outdoor project, it’s important to consider an area’s airflow as you’ll want to maintain a constant supply of fresh air.

Heavy rainfall

The primary concerns with heavy rainfall are flooding and structural integrity.

Flooding

Coastal regions are already witnessing increased flooding as sea levels rise and inland areas are seeing record levels of rainfall year on year. As mentioned above, the increased capacity of the atmosphere to hold moisture means that the amount of rain falling in any given storm is increasing in intensity. Allowing for flooding in new and unexpected areas requires a careful evaluation of proposed locations for new outdoor spaces. Proximity to rivers, streams and other natural sources will need to be considered carefully. The capacity of drainage will need to increase to account for ongoing food trends. Sustainable drainage systems (SUDS) can reduce the amount of water that flows from a home into a drainage system, by storing and releasing it over time, reducing the risk of further flooding. Another solution is to design an area of the garden to direct water towards a low-set area containing hardy and thirsty plants.

Structural Integrity

A big concern that comes with heavier rainfall is the weakening that it can cause to the foundations of outdoor spaces. When soil, especially clay-based soil, becomes saturated with water, it can cause the ground to shift. Shifting ground can compromise shallow, unprepared foundations. For projects built on clay, it is wise to consider deeper foundations in preparation for more extreme weather. In all designs, it is advisable that a cistern system be installed around the foundations to direct water away from the site.

Climate change and outdoor design - Conclusion

Outdoor spaces will be unaviodably affected by the forecasted changes to our climate. As we learn more about the expected impacts of climate change, we’ll need to reevaluate our built environment to ensure the long- term sustainability and endurance of any outdoor space. In this guide, we’ve discussed two of the most prominent issues expected to result from climate change. Being aware of these issues, and their potential solutions, will help to improve design for the future.