How to map and monitor care

Strategies for the Peri-Urban ecosystems’ development as hybrid ecologies


This essay aims to look at the potentials of Green factor tools applied in high-density urban areas and assess their possible use for the development of the peri-urban context. Through understanding it.s entanglement with national and local policies and the advantages seen in the testing areas in densely urbanized cities, the research hopes to propose a tool that can mitigate the expansion of cities into wildlife ecosystems by taking into account complex environmental factors.


Green Space Factor (GSF) schemes are tools that offer numeric value for green infrastructural elements in relationship to the built area of a particular site, by helping translate greening policy objectives into practice. RED. The aim of such schemes is to help improve ecological sustainability by increasing the total green area (Stenning, 2008). Usually, a GSF is applied to development proposals on already developed land but has however the potential to be used in order to show how development may change the ecology of an undeveloped site and assist in comparing proposals.


Beginning with Berlin in the 1990s, GSF schemes have spread to other German cities (including Hamburg) and then overseas, including Sweden (Malmö), Finland (Helsinki), the United States (including Seattle and Washington DC) and Canada (Toronto). Southampton was the first UK authority to develop a GSF scheme. A partnership led by the Red Rose Forest, developed a GI Toolkit, based on a GSF approach, for England’s North-West region in 2008 (14)


Berlin conceptualized for the first time a green space factor in order to counter the imbalance in open, green spaces in the densely built inner city. Called Biotope Are Factor, it proposed to ecologically upgrade private property plots. At first, the initiative was proposed as a part of the landscape plan, making it mandatory to incorporate the BAF factors into new developments. Outside this area, the BAF works as a voluntary guideline to encourage the incorporation of environmental features.

The weakness of this approach is that it is indifferent towards different types or qualities of vegetation. For example, an area with sparse vegetation and a group of trees with extensive undergrowth of equal area would receive the same score as long as the topsoil surface is connected with the subsoil. (Vartholomaios, 2013)


The city of Malmo introduced for the development of the city harbour into a sustainable urban district, the green space factor. Although built on the example of Berlin, the GSF made it possible to layer different surface types, while also factoring in different vegetation qualities. A Green point checklist is used to complement the otherwise hard to standardize or quantify landscape qualities that cannot be factorized. The first stage of the harbour development, the neighbourhood of Bo01, with the minimum GSF target of 0.5 is considered a leading example for ecological urbanism. However, during the next development stages, the minimum target became relative to the building coverage, under the pressure of achieving environmental goals with realistic costs.


The North West Development Agency developed the Green Infrastructure Score as part of its “sustainable building policy”. Here, similar to the green point system of Malmo, the GI score is used together with a GI intervention worksheet. However, after 2011. The policy was brought down to the status of guidance, with planning applications that justify how multiple benefits are achieved through developing the site would be considered favourable. These benefits are set by Natural Economy Northwest, include climate change adaption, flood alleviation, biodiversity, and place equality. Vegetations planted on topsoil connected to the subsoil and green roofs score highly. (13)

SUMMARY- Green Factor tools

To conclude, we can assume that the concept of the green factor. although some minor modification was made to the proposed ecological priorities, and in order to adapt to local planning conditions, has not changed since it’s the first application in berlin. For now, it seems to be still in a trial period, with only a few pilot tests being carried out in particular neighbourhoods, without it having been applied to a wider scale yet.


GSF = ∑t (areat x factort) / total area

In the green space factor (GSF) schemes, various surface cover methods are given a factor between 0 and 1. The factors are assigned on the basis of water-holding capacity of the surface cover of the proposed developments, ranging from 0 for completely sealed surfaces to 1 for natural covers of a particular depth. These provide a simplified measure of the potential for rainwater infiltration which is the most accurate proxy for “naturalness” of a site.

In order to calculate the Green Space Factor, each particular surface cover is multiplied by its assigned factor. Then the multiplied sums are added together and divided by the overall site area (see diagrams 1 and 2) which ultimately reveals a GSF score of the development in question.

By assigning a minimum target for different types of development and land use by the planning authority, developers have a better understanding of what is expected of their development in terms of green infrastructure and control the improvements brought to plans if the target had not been reached. The thus simplified identifying of planning proposals with insufficient urban greening can encourage substantial improvements to plans.


Flexibility and stakeholders

Flexibility and ultimately the low interference of the GSF schemes with the design freedom is the most appreciated benefit of GSF schemes. Although a minimum target is set, the ways in which to achieve it is non-prescriptive with respect to plot layout and landscape design and is entirely left up to the architects and developers, while providing them with a break-down of green infrastructure elements and their scores to choose from. Overall, many respondents saw a great benefit in the tool providing numeric values to assessing green infrastructures. This was considered by planners to be crucial in persuading other stakeholders of the necessity of including green infrastructures in new private developments. (Juhola, 2018)

Flexibility is praised also in the sense of this method being transferable from one area to another and implemented with minimal changes. However, this essay argues that the flexibility and transferability of methods must be carefully considered in the ecological context of their implementation. Such issues are discussed in-depth in the next chapter. At the same time, the regulatory role of the minimum target ensures the meeting of a particular target, rather than time and labour-intensive dialogues with developers and the planning committee or the need for incentives. (Vartholomaios, 2013)

Also, because it is built on the same two-dimensional logic as planning ratios and is directly derived from concepts such as lot coverage and density, planners and developers can quickly adapt and incorporate these schemes in their processes. The calculations of the overall score are straightforwards and the purpose is clearly stated, which makes the use of GSF schemes and inexpensive process. At the same time it is easily understood by non-specialists, makes it easier for the public to argue for more ambitious schemes in their neighbourhoods.

Depending on the operation of GSF schemes, they have the potential to encourage developers to take specialist advice in order to ensure their proposals satisfy the planning authority requirement.s (Greater London Authority, 2017)


Generalization and lack of monitoring

When discussing flexibility, concerns have been raised that GSF schemes, by applying to sites individually, would not approach the need to propose green infrastructures as part of a complex network and that though achieving great flexibility and transferability, they would disregard the specificities of the individual ecological context. By not assessing how these green infrastructures link to wider ecological networks, and by keeping the.. determined only by quantity and type for individual developments, there is a danger for schemes to be approved that that would be sub-optimal. Flexibility, that, on one hand, is beneficial for the seamless implementation of such schemes, it can bring out issues of generalizability, as noted in the literature (Thorén, 2000).

While there is a need to develop a tool that can be widely used, it ought to incorporate local differences and special conditions. (Bugs et al., 2010)

Other dangers identified in the stakeholder’s discussion in 2017 in London…. Are of the tool being understood as a tick box and it might even be seen as an alternative to inquiring expert advice on meaningful ways to implement green infrastructures. This seems to create a real possibility for low-quality features to be proposed just in order to meet the GSF target score. For example, green roofs with inadequate substrate depth or development with planted trees with not enough rooting medium (10 cubic meters instead of 25) which over the long term would not be able to provide the full range of benefits of extensive and healthy tree canopies. Thus, it is crucial for synergy with other benchmarking methods to be planned out.

In their current development, GSF methods strictly regard the planning phase of the development without providing schemes of monitoring implementation nor evaluation of progress over a longer period of time. The commitment in terms of financial resources and labour from the local authorities for ongoing evaluation of the implementation of green infrastructures has been identified as a substantial weakness of the current form of GSF schemes. (Kruuse, 2011) Finally, the voluntary nature of the tool may lead to them being used for marketing purposes, only when convenient to the developer. The visual symbols of green infrastructural elements. (*greenwashing)


What GSF is not. A breakdown of other benchmarking methods

So far green factor tools have only been implemented at private development levels as methods of provision for green infrastructures, concerning plots of land individually. Public green spaces have been left to be promoted by other planning policies, that exist to ensure sufficient quantity of parks and other public green infrastructures, already in place. While this approach allows for a seamless implementation of a tool such as green factor into the fabric of any city, it provides a discrepancy in understanding ecologies as borderless entities.

In a discussion held in London in 2017, city planners, and other stakeholders who are familiar with existing regulations, identified a number of constraints provided by local planning regulations, that would limit what can be done, even if suggested by a green factor tool. Keeping the tool, on one hand, voluntary, and on the other only applicable to singular private properties, it is unclear how it can be holistically implemented in the planning process. At the same time, unless such tools become legally binding, and if the use of these tools is voluntary it will lead to little changes in future developments. (Momm-Schult et al., 2013).


In the 2017 stakeholder discussion held in London on 17 may, concerns were raised around the limitations of GSF schemes in relation to sustainability assessment schemes such as BREAM. It is important to understand the influence of certification or benchmarking methods the functioning and success of GSF schemes if developed accordingly.

BREEAM is a certification method designed to assess the sustainability and performance of residential and infrastructural developments. It considers landscape and ecology through assessment of 5 distinct categories. These are site selection; ecological value of sites and protection of ecological features; mitigating ecological impact; enhancing site ecology and long-term impact on ecology. (

Unlike GSF schemes, BREEAM assessments require surveys and reports by experts to be carried out, which contribute to substantial costs added to the development. These two methods cannot be used interchangeably and must not be confused because they do not perform the same functions. While GSF schemes should be understood as tools for the planning committee, that can be used to improving green infrastructure provisions across planning zones, BREEAM schemes ensure the carrying out of the crucial tasks of understanding large scale ecologies that form in these areas. This essay argues that in order to develop future cities sustainably, especially in regard to the expansion of the urban more into the natural, a synergy of these two methods must be developed, to ensure a hybrid environment for the life of both humans and other than humans, as integral parts of nature.

Nature and natural infrastructures should no longer be considered as adornments to the built environment but as an essential component of the urban fabric. (Greater London Authority, 2017)

In the next chapter, the paper aims to discuss a possible model that combines private and public development, and explain how this has the potential to elevate the future development of cities?


For this theoretical experiment, the Site of the Leamington, Warwick and Whitnash peri-urban situation has been chosen as an example.

This case study showcases, on one hand, the sharp border transition between urban and rural ecosystems, imposed by the green belt around the eastern and northern edges of the urban development. This measure of containment leads to a further dense expansion of the urban fabric towards the southern border (as seen) in the images 1–3. The city council then furthered the establishment of a natural public park to stop the unregulated development of the rural fabric. Such strategies have proven to have a destructive effect on the further densification and housing crisis in city centres, making the conservation of green infrastructures and inner-city natural ecologies almost impossible to be sustained.

At a larger scale, a paper published by the planning body of London Society, argues that a “green sprawl” stretching as far as 35 miles beyond the capital is no longer appropriate when London’s population is growing “at a rate equivalent to adding the UK’s second-biggest city, Birmingham, every 10 years”.

At a time in which political pressure is exerted on the conservation of green belts, it is important to raise questions about the future of British cities in expansion. The archaic understanding of nature as the “other”, as a virginal entity that needs protection, ultimately denies its agency and furthers the rhetoric of clear distinction between man and nature, instead of creating new strategies for these to coexist through practices of care and commoning.

This paper wishes to argue that it is crucial to extend tools such as the green factor to the yet to be legitimized peri-urban zones and that regulating future urban environments as hybrid ecologies is a more sustainable approach for the future of life in cities.

it is time to “move away from the simplistic and naive idea that that countryside is a sacrosanct patchwork of medieval hedgerows” towards a new position recognising “housing as a need to be met in locations with appropriate environmental capacity”.


Thoughts on redesigning the green factor specifically for “peri-urban” environments.

Considering the case study, five points have been drafted to stimulate a new kind of development of the peri-urban zoning. These points could be used as the starting point for the development of a specific GSF tool:

o Density. This paper draws attention to the close resemblance of the modes of calculation between green factors and density regulations. As such, for the peri-urban context specifically, long-term regulation of incremental increase in density, that closely observes the changes in ecosystems could contain the urban sprawl while allowing for a hybrid environment to organically progress. The long-term development regulations could also allow for the peri-urban, understood as a territory with specific density and development requirements to naturally shift outwards, allowing for cities to grow, without damaging ecosystems or existent green infrastructures

o Private and Public. As identified in this paper, the green factor tool application is limited to the private development sector, leaving public green infrastructures to be accounted for by other policies. For the peri-urban zones, this paper suggests a holistic approach in which new developments could be clustered into blocks of land, and thus … at a wider scale. The nature of each individual development would therefore be dependent on the neighbouring site of the same cluster. Furthermore, for each cluster, a percentage of publicly accessible green infrastructure could be imposed.

o Typology of Land Use. The paper suggests that in a peri-urban environment, a myriad of more typologies of land use should be included. Such, in each cluster, the inclusion of a diversity of small-scale agricultural land, high-rise housing units, and public spaces would be regulated. This would have the potential to provide neighbourhoods with new types of micro commerce and job opportunities.

o Maintenance. As mentioned in the previous chapters, a legal or community-based body should be appointed to closely follow the maintenance of build green infrastructures to assure the sustainability of the promised green factor at the time of the development proposal and to also allow for a better understanding of the use of such tools on a long term. It is important for planning authorities but also for the future communities to understand who accounts for the maintenance of the green elements and where concerns about improper functioning can be raised.


Developing a green factor tool for the future city must not only focus on new strategies to “green up” high-density city centres but should incorporate the fictional edges of cities. By acknowledging the need for the peri-urban fabric to be legitimized as a distinct zone with specific planning regulations, we open the possibilities for hybrid environments to be achieved, and cared for, individually for each city and its surrounding ecosystems.


(1) Arnfield J., 2003. Two decades of urban climate research: A review of turbulence, exchanges of energy and water, and the urban heat island, International Journal of Climatology;

(2) Grant, G., 2017 Greater London Authority, Urban Greening Factor for London Research Report;

(3) Juhola S., 2018, Planning for a green city: The Green Factor tool;

(4) Kruuse A., 2011. GRaBS Expert Paper 6: The Green Space Factor and the Green Points System;

(5) Stenning, E., 2008. An Assessment of the Seattle Green Factor: Increasing and Improving the Quality of Urban Green Infrastructure;

(6) Thorén, K.H., 2000. The green poster: A method to evaluate the sustainability of the urban green structure. Environ. Impact Assess. 10.1016/S0195–9255(00)00047–0;

(7) TCPA, London, (accessed December 17, 2020);

(8) Vartholomaios, A. et al, 2013, The green space factor as a tool for regulating the urban microclimate in vegetation-deprived Greek cities;

(9) Warwick District, 2015, Local Plan Additional Site Options Ecological Assessment;

(10) (accessed December 16, 2020);

(11) (accessed December 16, 2020);

(12) (accessed December 16, 2020);

(13) (accessed December 16, 2020) ;

(14) (accessed December 16, 2020);


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(Fig. 4) Local plan policies map,

(Fig. 5, 6, 7, 8) 52.262916, -1.548141, Google Earth,