The Grenoble metropolis and energy sobriety

Chaire Paysage et énergie (ENSP), 2022

To download : 1647_244_dp-bilan-des-mesures-de-sobriete_grenoble.pdf (410 KiB)

The Grenoble metropolis, « at the end of every street, a mountain » (Stendhal)

1 - Nature and culture, the figure of the mountain

The Grenoble metropolitan area is surrounded by three mountain ranges: the Vercors, the Chartreuse and the Belledonne chain. Grenoble occupies the place of an ancient lake created by the melting of the glaciers that filled the Isère valley some ten thousand years ago. It is mainly built on a plain at the confluence of the Isère and Drac rivers. The town is attached to the strong landscape figure of the Alpine mountains. Symbols and values related to the mountain have built its personality. The presence of the mountain is important (visually, economically, activities related to the mountain, etc.).

2 - Grenoble, a territory of science and innovation

The strength and uniqueness of Grenoble’s geographical setting and resources (hydrology, mines, etc.) attract and retain companies and researchers. Since the 18th century, scientific disciplines have developed here. Hard sciences, such as mathematics, physics and chemistry, have become part of the region, in line with the progressive thinking of the time. More recently, other disciplines such as medicine, biology and social sciences have flourished. Industrial and technological activities play an important role.

3 - A desire for nature in the city for an expanding metropolis

Around Grenoble, the agricultural and urban territory is characterised by a diversity of landscapes, with a wide variety of local products from dairy, cereal, horticultural, market garden, livestock, wine and bee farms and a wide variety of town and village typologies. Agriculture in the Grenoble conurbation is characterised by three types of areas

• a rich agricultural plain due to a silty soil and a water table less than three metres deep: the plain represents an area of large-scale farming and market gardening;

• the hillsides where livestock farming, arboriculture and viticulture are practised;

• the mountains, where livestock farming remains with a few small dairy basins, while the rest of the area has been abandoned.

Land and urban pressures linked to the expansion of the city threaten the agriculture of the plains and hillsides.

Rural and urban areas are now at the heart of a growing urban demand for sustainable management of spaces and resources. The discourse of the various users converges towards a renewed desire for nature in the city, as the countryside becomes increasingly distant.

4 - Pollution and risks

Grenoble’s topographical and geographical situation means that urban pollution is perceptible on a daily basis. A blanket of air pollution filling the « bowl » of the city is visible to the naked eye at several times of the year.

The transformation of mountain territories in the face of global warming is also known, with a retreat of glaciers and a loss of mountain biodiversity. The risks of collapses and floods threaten the city. The various political discourses integrate these challenges, and it is in this context that the metropolis is implementing its climate, air and energy plan and its various mobility and public space projects.

Climate, mobility and public spaces: ambitious objectives supported by public actors

1 - Climate, air and energy plan, awareness and action

The presence of pollution and its geographical location make Grenoble a fragile territory. The city has a community of researchers associated with research laboratories and who teach in schools on climate issues. Public policies highlight these ecological and climatic issues, with the desire to reduce greenhouse gas emissions through the use of renewable energies and energy sobriety in all aspects of urban planning (mobility, heating networks, energy production, public space planning, etc.).

In 2004, Grenoble-Alpes Métropole was the first French territory to set up a climate and energy plan. It provides for the installation of renewable energy sources (ENR) as well as a series of thermal renovations of buildings. One example is the construction of urban gas networks supplied with biogas, used in particular for bus and tram traffic. A second climate, air and energy plan will be produced in 2019. This plan will further integrate issues of public space planning, taking into account the tools created by the various departments of the metropolis as they go along.

2 - Chronovélos, a new soft mobility network built with the inhabitants

In 2014, the metropolis launched an ambitious urban transport plan (PDU), implementing the reduction of greenhouse gases and energy sobriety. The main structure of the PDU is based on the issue of cycling. A consultation was carried out in order to plan a network of projects. The basic objective is to triple the modal share of cycling in daily journeys (58,000 journeys/day in 2014, source: Plan de déplacement urbain 2030, Grenoble conurbation) The various levers used are

• education

• rental services

• parking

• infrastructure The metropolis first commissioned a group of residents to think about this project. Subsequently, the city’s agents carry out additional studies over a period of one year.

In 2016, the Chronovélo network, consisting of a series of cycle paths and « cycle highways », began to be deployed throughout the city.

3 - A common culture of public space supported by the metropolis

In 2016, the metropolis produced a metropolitan guide to public spaces and roads. This guide takes into account the studies carried out for the PDU. The PDU and the guide for public spaces are subsequently included in the 2019 climate and energy plan.

The purpose of the guide is to build a common culture of public space on the scale of the metropolis, despite the diversity of the territories involved. This general intention is expressed differently according to the territories concerned, and is based on several points of vigilance concerning, in particular, questions of energy sobriety associated with the desire for a comfortable living environment:

• generalisation of the 30 km/h speed limit in the heart of the city

• reduction of heat islands with different types of urban development (planting, soil sealing, etc.)

• 50% of public space will be dedicated to « social intensity » (i.e. to soft modes of transport, bicycles and pedestrians) in 2030.

• a low-emission zone limiting the circulation of the most polluting vehicles in 27 municipalities of the conurbation

For these different objectives, quantified targets for de-silting, water drainage, reduction of heat islands, improvement of the living environment and comfort through public development are achieved as the various urban planning documents produced by the metropolis evolve.

Sobriety, a basic principle for a global reflection on the construction of the territory

1 - Road regulations and changes to public space

In 2016, the speed limit was generalised to 30km/h in urban areas throughout the metropolis. The various mayors accepted this new rule, but were concerned about the possible proliferation of road signs. The metropolis is therefore setting up a system of markings on the road so that the urban landscape is free of the visual and physical clutter of signs.

At the same time, the roadways are being recalibrated to make more room for pedestrian traffic.

2 - Taking into account the landscape as a living environment for urban planning

The 2016 Metropolitan Guide to Public Spaces and Roads has several thematic sections, exploring all aspects of urban planning carried out by the metropolis. Dimensions related to landscape issues are strongly taken into account, as components influencing lifestyles. Issues related to energy sobriety and the reduction of greenhouse gases motivate the development of a metropolitan metabolism. They are addressed as non-negotiable data to be taken into account in urban planning processes. All projects carried out at the metropolitan level are subject to an analysis grid. The agents of the metropolis push the politicians, the technicians and the designers. The implementation of the project approach is particularly interesting: ambitions are set collectively, tools are proposed, and human resources are made available to find solutions through a project approach and not through vertical regulations.

3 - Citizen participation to plan mobility

As part of the preparation of the PDU, concerning the desire to increase the network of bicycle mobility, the metropolis commissioned a group of inhabitants to reflect on the idea of a bicycle highway. This group of residents is composed of :

• 1/4 bicycle specialists

• 1/4 bicycle users

• 1/4 representatives of neighbourhood associations

• 1/4 non-bicycle users.

At the end of this one-year citizens’ mission, a report is produced by the residents, with a set of specifications. Each section of the network is designed to fit into its environment, and is the subject of a global urban reorganisation. Thus, issues other than cyclability are taken into account on most sections. In the following year, additional studies were carried out by the metropolis.

A link is made in these studies between mobility, energy efficiency and the comfort of the living environment, for the composition of an urban landscape. When walking in Grenoble, the Chrono vélo network is indicated by yellow and white markings on the ground. The transformed landscape can in some places raise questions. The Chrono Velo routes are designed as roads, with little urbanity embodied in the public spaces offered to all pedestrians and cyclists. The ground treatment is asphalt and the curbs are thick.

However, it is quite impressive and interesting to use this network, which serves the whole of Grenoble well and is increasingly extending outwards. Few French cities with a defined cycle network can stand comparison. Combined with dedicated bus lanes, the cycle paths are part of a very wide road space, sometimes up to 15m. In most cases, the space for bicycles is taken from the space for cars. In some places, this results in a lack of space for tree planting due to reduced pedestrian pavements. However, an effort has been made to provide planting on certain tracks. At the same time, the public transport offer has been strongly developed over the last few years, allowing (together with cycling) a strong reduction in the use of cars in the city centre and therefore in the amount of space dedicated to them.

The climate, air and energy plan, transition and nature in the city

1 - Follow-up to the climate air energy plan

Following its first climate air energy plan, a very large number of inter-municipalities are implementing this type of planning. The Grenoble metropolis is an inspiration for many. With the updating of its climate air energy plan, the metropolis continues its actions in favour of the production of renewable energy and energy sobriety. One example is the new BIOMAX wood-fired power plant producing both electricity and heat, which will open in 2021. In addition to the existing wood-fired power stations, the urban heating network is thus supplied 100% by renewable energy.

2 - Fertile reclamation

The territory of the metropolis extends into rural mountainous areas. There is therefore a great diversity of contexts, from the large city to the small village belonging to the Chartreuse Regional Park. It is therefore complicated to set up global policies, because it is not possible to homogenise them.

The question of vegetation in the city seems to be one of the issues emerging today, mainly in the context of the city of Grenoble. There is a large network of existing parks, but there is a growing desire to increase the proportion of green areas. This is in line with energy sobriety and adaptation to global warming, with the storage of CO2 and the reduction of heat islands, and in the sense of landscape with the improvement of the urban environment in all senses of the term (aesthetics, health, conviviality, etc.).

The park network is of high quality and offers generous green spaces. Greening actions are implemented with « Jardinons nos rues ». The city of Grenoble provides gardening spaces on the public domain. If the project involves the greening of a façade, the city can provide a grant to cover part of the cost of installing trellises for climbing plants.

One example is the study carried out on the Cours de la Libération as a way of taking account of plants in urban studies. The metropolis entrusted it to the landscape design office « Atelier des cairns ». A double row of plane trees in poor health serves as a starting point for thinking about the future of mature urban planting. Chronovélo paths are present in the counter-alleys, and the landscape designers are thinking about improving them by restoring places for walking. This study serves as a coordination and phasing tool for the city’s services in the event of a project carried out on an avenue where the same type of problems are found.

Sources

To go further