Green factor in Tuusula as a tool for land use planning

Urban densification is considered beneficial in terms of mobility and services. However, densification overlooks the importance of forests, green corridors and local nature. These are essential for the well-being of people, animals and plants. With climate change and the loss of biodiversity, we need a tool to calculate the importance of forests and green cover. If the starting point for building new residential areas is to destroy vegetation and the only green environment is a man-made park, we will lose our direct contact with diverse nature.

Tuusula must set an example for its residents in the areas of social and ecological activity, and green space calculation formulas must be adopted in land use planning as soon as possible. The green factor is a tool that can be used to calculate the amount of green canopy cover. Land use planning determines how much of the natural environment is preserved on an area- and plot-specific basis. If the amount of greenery is not controlled as urban centres become denser, it will be difficult, if not impossible, to add greenery to an already built-up environment. Therefore, green construction and the space it requires must be taken into account when planning construction. The basic formula for the green factor is weighted green area divided by the area of the plot. However, a preserved tree, for example, is worth many times more in points than a square metre of lawn.

Justification:
When green areas are lost, part of the biodiversity is lost, the possibility of urban flooding increases as impervious surfaces increase, and people’s opportunities for recreation in the local nature are reduced. Vegetation can reduce the adverse effects of the heat island phenomenon, create a pleasant environment and provide habitats for other species besides humans. The heat island phenomenon refers to the warming of the microclimate caused by building masses and asphalt surfaces, especially in summer. Its intensity is influenced by factors such as the area of the city, the size and density of buildings, the volume of traffic and energy consumption.

Vegetation-covered and permeable surfaces are also often cheaper to implement than impermeable surfaces, and they are also suitable for animals. Since the monetary value of vegetation has not been quantifiable until now, there is a great temptation to build square metres that can be measured directly in monetary terms.

It is possible to calculate retrospectively how much it costs to plant a new tree: the seedling costs money, the use of an excavator and transport vehicle costs money, watering and caring for the new seedling costs money. When a stately pine tree is felled, it is estimated that it will generate €100 in sales revenue. However, according to estimates, purchasing and planting a new sapling a few metres tall can easily cost several hundred euros. The value of a tree in terms of landscape and carbon sink is many times its raw material price. And even then, as recently happened in Tuusula, 17 planted hardwood trees died.

The green factor is used in several cities, including Oulu and Helsinki. Calculation methods can be found on the website. The basic formula is that the green factor of a plot or area is calculated by dividing the scored amounts of natural trees and other elements by the area of the plot or area. The aim is to leave some coverage and green space. For example, leaving one tree is worth many times more than a square metre of lawn. The green factor is a measure of the green space in a city.

The key to implementing the green factor is to define calculation formulas and require that new residential areas comply with the calculations. It is not enough for the plan to state that existing vegetation will be preserved. An example of this can be found in the plan for the business area. The trees have been cut down, even though the plots could have been sold to buyers, and the building plan requires that the plot show how trees will be preserved. The builder would then have implemented the placement of trees on the plot.

EU restoration proposal
The EU proposal to increase biodiversity by 15 per cent by 2020 failed to achieve its goal. It failed because it was based on voluntary action. It also failed in Tuusula because Tuusula is building its new residential areas by first completely destroying the canopy cover, for example in the housing fair area, the Häriskivi area and the Rykmentinportti business area. According to the EU restoration proposal, in cities, smaller towns and suburban areas, the amount of green areas and tree cover should remain unchanged by 2030 compared to 2021 levels, increase by 3% by 2040 and by 5% by 2050.

A pleasant green environment is an attractive feature and represents only a small part of the total cost of a construction project. The use of green efficiency aims to steer the construction of environments that are environmentally responsible and take human well-being into account.

Green space calculation formulas should be adopted as soon as possible in land use planning. When a municipality has hundreds of hectares of forest, the three per cent increase in green space required by the EU means a large increase in the number of hectares required to meet the canopy cover requirement. The practice of clearing forests to make way for new residential and business areas is unsustainable and makes it difficult to achieve the canopy cover target in a situation where the aim is to achieve carbon neutrality, biodiversity and the well-being of residents. Tuusula must either lead the way or at least comply with EU and national agreements and commitments and do its part to stop the destruction of forests.

This content has been translated using AI

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