Why are Trees Absolutely Your Best Natural Airco?

(Photo by Sandro Gonzalez on Unsplash) Energy costs continue to rise across Europe and the prices are not going to lower soon. So finding cost-effective and environmentally friendly cooling solutions has never been more crucial. We all know that air conditioning (airco) units provide immediate relief from the heat, but trees offer a sustainable, economical alternative that reduces both indoor and outdoor temperatures.

So, next to enhancing the aesthetics of urban landscapes, they also provide a natural air conditioning system that can lead to substantial energy savings and a more comfortable living environment.

We crunched some numbers for you and looked into the best possible trees to plant in order to maximize the cooling results.

Cooling Mechanisms of Trees

Trees cool their environment primarily through shading and evapotranspiration.

They block direct sunlight, reducing surface temperatures by 11-25°C. This effect is particularly noticeable in areas with extensive canopy cover, protecting buildings and pavements from the intense summer sun. For instance, a car parked under a tree in Davis, California, was found to be 25°C cooler than one parked in direct sunlight.

Trees also absorb water through their roots and release it as water vapor through their leaves. This process uses heat energy from the surrounding air, effectively lowering ambient temperatures. A mature tree can transpire up to 378.5 liters of water per day, providing a cooling effect equivalent to five standard air conditioning units running for 20 hours​.

Economic and Health Impact of Trees for Cooling

The financial benefits of using trees for cooling are substantial. In the UK for instance, the average monthly electricity bill is around €93 (£80.40), with electricity prices in the EU averaging €0.28 per kWh and reaching up to €0.50 per kWh in countries like Germany and Ireland​​. Strategically planting trees can reduce energy bills by €20 to €30 per month during the summer by lessening the reliance on air conditioning units​.

In addition to cooling, trees offer numerous environmental benefits. They improve air quality, sequester carbon, and support biodiversity. Unlike air conditioning units, which can increase outdoor temperatures and contribute to greenhouse gas emissions, trees provide a natural and sustainable solution to urban heat islands. These areas, characterized by higher temperatures due to dense infrastructure, can see temperature reductions of nearly 7°C with increased tree cover.

Best Trees for Cooling in Europe

When selecting trees for maximum cooling effects, consider species that are well-suited to the local climate, offer extensive canopy cover, and have robust growth characteristics. Here are some of the best options for Europe:

  • London Plane (Platanus × acerifolia): Known for its large size and extensive canopy, the London Plane tree is highly effective in providing shade and cooling. It is also tolerant of urban pollution and poor soil conditions. Commonly found in cities like London and Paris.
  • European Beech (Fagus sylvatica): This tree offers dense foliage and a broad, spreading canopy, making it excellent for cooling large areas. It thrives in temperate climates and is common in parks and woodlands across Europe.
  • Common Oak (Quercus robur): With its broad canopy, the Common Oak provides extensive shade and is long-lived. It is well-suited for most parts of Europe, especially in the UK, France, and Germany.
  • Silver Linden (Tilia tomentosa): Known for its dense canopy and fragrant flowers, the Silver Linden provides excellent shade and is resistant to air pollution. Commonly found in Central and Eastern Europe.
  • Norway Maple (Acer platanoides): This tree has a broad canopy and is highly adaptable to urban environments, making it effective in cooling urban heat islands. It is widely planted in Northern and Central Europe.

At What Age is a Tree Big Enough to Cool?

Trees begin to provide noticeable cooling benefits once they have established a certain canopy and root system. Generally, this occurs several years after planting. The exact age at which a tree becomes effective for cooling can vary depending on the species, growing conditions, and care. Here are some key points:

General Timeline

  • 3-5 Years: Trees start to provide some shade and cooling benefits. Young trees with healthy growth will begin to offer limited but noticeable cooling through shading and evapotranspiration.
  • 10-15 Years: Trees typically reach a stage where they can provide substantial cooling effects. At this age, many species have developed a broad canopy that significantly reduces temperatures through shading and increased evapotranspiration.
  • Mature Trees: Trees that are 20 years or older often offer the maximum cooling benefits. They have fully developed canopies and root systems, optimizing their ability to reduce surrounding temperatures.

Species-Specific Growth

  • Fast-Growing Species: Species like the London Plane (Platanus × acerifolia) and Silver Maple (Acer saccharinum) can start providing considerable shade and cooling benefits within 10 years due to their rapid growth rates.
  • Medium to Slow-Growing Species: Trees like the European Beech (Fagus sylvatica) and Common Oak (Quercus robur) take longer to mature but provide extensive cooling benefits once they reach maturity, typically around 20 years.

Factors Affecting Growth and Cooling Ability

  • Soil Quality and Water Availability: Trees grown in nutrient-rich soil with adequate water will establish more quickly and provide cooling benefits sooner.
  • Care and Maintenance: Regular care, including pruning, fertilizing, and protection from pests, can enhance a tree’s growth rate and health, accelerating its ability to provide cooling.
  • Climate and Location: Trees in optimal climates with suitable growing conditions will mature faster than those in less favorable environments.

Practical Implementation

For maximum cooling benefits, trees should be planted on the south and west sides of buildings to block the most intense sunlight. Deciduous trees are particularly effective as they provide shade in the summer and allow sunlight through in the winter when their leaves have fallen. It is essential to plant trees at an adequate distance from buildings to prevent root and branch damage.

In short, we know that airco units provide quick and controllable cooling, but their environmental and financial costs are high. Trees offer a sustainable, cost-effective, and environmentally friendly alternative.

By strategically planting trees around homes and buildings, you can largely reduce your energy costs and contribute to a cooler, healthier environment. So, embrace the natural cooling power of trees, and let nature be your best air conditioning system!