ENERGIEThis ENERGIE publication is one of a series highlighting the potential for innovative non-nuclear energy technologies to be applied widely and contribute to provision of superior services. European Commission strategies aim to influence the scientific and engineering communities, policy makers and key market actors so that they develop and apply cleaner, more efficient and more sustainable energy solutions to benefit themselves and society in general. Funded under the European Unions Fifth Framework Programme for Research, Technological Development and Demonstration (RTD), ENERGIEs range of supports cover research, development, demonstration, dissemination, replication and market uptake - the full process of converting new ideas into practical solutions to real needs. Its print and electronic publications disseminate the results of activities carried out under current and previous Framework Programmes, including former JOULE-THERMIE actions. Jointly managed by the Directorates-General Research and Energy & Transport, ENERGIE has a total budget of 1042 million for 1999 to 2002. ENERGIE is organised principally around two Key Actions, (Cleaner Energy Systems, including Renewable Energies, and Economic and Efficient Energy for a Competitive Europe), within the theme Energy, Environment and Sustainable Development. With targets guided by the Kyoto Protocol and associated policies, ENERGIEs integrated activities are focussed on new solutions which achieve balanced improvements in Europes energy, environmental and economic performance and thereby contribute towards a sustainable future for Europes citizens. Produced by Energy Research Group, University College Dublin, School of Architecture, Richview, Clonskeagh, Dublin 14, Ireland Tel: + 353.1-269 2750, Fax: +353.1-283 8908 WWW: http://erg.ucd.ie/, E-mail: erg@erg.ucd.ie Written by: Vivienne Brophy, Crea ODowd, Rachel Bannon, John Goulding and J. Owen Lewis Design: Sinad McKeon and Pierre Jolivet

with the support of the EUROPEAN COMMISSION Directorate-General Energy & Transport AcknowledgementsWe would like to thank the following who supplied valuable information for this publication: Case study material: Anke Benstem, KUKA (Kronsberg Environmental Liaison Agency), Germany; Cathie Curran, Richard Rogers Partnership, UK; Christine Oehlinger, O.. Energiesparverband, Austria. Photographs and diagrams: Alfanso Sevilla, Geohabitat, Almeria, Spain; Tjeerd Deelstra, Ministry of Housing, The Hague, Amsterdam; Marylene Ferrand, FFL Architectes, France; Bill Hastings, ARC Survey, Ireland; Jaime Lopez de Asiain, ETS de Arquitectura de Seville, Spain; Maurice Stack, Architect, Ireland; Derry OConnell, John Goulding, Brian OBrien and Crea ODowd, University College Dublin, Ireland; International Dark Sky Association. Expert review: Philip Geoghegan, Derry OConnell, University College Dublin, Ireland.

LEGAL NOTICENeither the European Commission, nor any person acting on behalf of the Commission, is responsible for the use which might be made of the information contained in this publication. The views given in this publication do not necessarily represent the views of the European Commission. Reproduction is authorised provided the source is acknowledged. Printed in Ireland 2000

European

Commission

General information

Sustainable Urban Design

ENERGIE

Sustainable Urban DesignContents1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 2. Urban impacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 2.1 Ecological Footprint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 2.2 Urban Heat Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 2.3 Buildings and Land Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2.4 Traffic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2.5 Wastes (solid, liquid, gaseous) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2.6 Water Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2.7 Air Quality, Ozone Depletion, Greenhouse Gases, Solar Radiation . . . .4 2.8 Aerodynamic Impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 2.9 Urban Dust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 3. Urban Design Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 3.1 Site Selection and Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 3.2 Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 3.3 Climate Optimisation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 3.4 Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 3.5 Resource Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 3.6 Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 4. Selected Design Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22 5. References and Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

This is an ENERGIE publication, funded under the European Unions Fifth Framework Programme for Research, Technological Development and Demonstration. Jointly managed by the Directorates-General for Research and Energy & Transport of the European Commission. Partners on the project were: Energy Research Group, University College Dublin, Ireland Institut Catala DEnergia, Barcelona, Spain O.. Energiesparverband, Linz, Austria

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1.

INTRODUCTION

Environment

Society

Economy

In urban settlements, where over 80% of Europeans live, the concentrations of people and their activities create intensified demands on the environment. However, this very concentration offers opportunities, through design and actions at an urban scale, to minimise the various environmental impacts - ideally to the point where they can be assimilated by the ecosystems of the region without lasting damage. It can then be said that a level of sustainable existence has been reached at which the community can live in symbiotic harmony with its environment. The best known definition of sustainable development, that of the World Commission on Environment and Development (the Brundtland Commission), dates from the publication in 1987 of Our Common Future [1]: (Sustainable development is)development that meets the needs of todays generation without compromising the ability of future generations to meet their needs. It is worth emphasising that it is our needs, not wants, that deserve primary attention. It is also worth reminding ourselves that we in the developed countries have used power and knowledge to help ourselves to a grossly disproportionate share of the world's resources leaving much environmental, social and economic degradation in less developed countries - and sometimes closer to home. There are many indicators of sustainability that can help in assessing the present condition, and strategies that may be adopted by a community to ensure its continued existence and development. An holistic, interdisciplinary approach involving the natural and physical sciences and the humanities is a feature of most comprehensive analyses, and the issues involved in developing and implementing action plans for sustainable urban living are diverse and often interdependent. While recognising that social and economic factors are also of fundamental importance, the focus of this maxibrochure is on physical environmental issues. It aims to outline some of the current thinking in urban design, and show some exemplary responses, as an aid to the process of making urban settlements in Europe more environmentally sustainable. 1.1 BACKGROUND

Sustainable Development

Sustainable development is development that delivers environmental, economical and social services to all residents of a community, without threatening the viability of the natural, built, economic and social systems upon which the delivery of these systems depend. [2]

Economy

Society Environment

Two models of sustainable developments.

Evaporative cooling at the Alhambra, Granada, Spain.

The knowledge of an appropriate response to climate was fundamental to the planning of many traditional settlements. Vernacular architecture and urban design often embodied an intimate knowledge of the locality, climatically and geographically, and its potential for sustainable life. Long before the Roman architect Vitruvius wrote the Ten Books of Architecture two thousand years ago, builders, were of neccessity, optimising their local environment, through the manipulation of site, the forms, organisation of external spaces, and the building layout itself. During the Industrial Revolution in the mid-1800s, the design of buildings came to depend less on ambient energy and more on the abundant supply of fossil fuels for their thermal comfort. Current trends in architecture and urbanism often continue to ignore the potential of passive measures to achieve thermal comfort. The resulting impacts can be measured in environmental, social and economic terms. There is increasing acceptance among planners, urban designers and governments that current modes of human existence in developed countries are unsustainable in environmental, social and economic terms. Some of the factors supporting this view are indications of: global climate change; resource depletion; droughts and floods; local pollution and damage to ecosystems; species extinction; deterioration in the quality of life, especially in cities; increasing polarisation in wealth distribution; and poor equality in access to resources and knowledge. The nature of the problem, now beginning to be recognised in broad terms and sometimes only from indications at a global or regional scale, is such that it is still possible to take corrective action and begin to halt the decline, and reverse it in many instances, if measures are urgently applied. However, failure to act appropriately at this stage may soon result in our having to face catastrophic failure of the

Evaporative cooling at EXPO 92, Seville, Spain.

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environmental (and socio-economic) systems on which our existence depends. Therefore, it is vital that we begin to understand in specific terms the damage we are doing and what measures can be applied to rectify that damage and support our continued existence and welfare. Many of these issues come to a focus in urban settlements. In general terms they may be considered as inputs and outputs of the urban system including: non-renewable and renewable resource use (both including energy); solid, liquid and gaseous wastes and their recycling, treatment or disposal; and manpower and knowledge.

Taking corrective action in the development of Curitiba.

Utilization of external spaces.

Input - output model of energy and material flows of a city.

More specifically, we can consider the environmental impacts of buildings, transport, industry and commerce, agriculture, institutions (education, health care, etc.), and recreational or social facilities and what is involved in their establishment and maintenance. Population size, its affluence and the extent and nature of its economic and social activities will determine the scale of the issues to be considered. Further subdivision and characterisation of these issues is addressed in this maxibrochure with the overall objective of raising awareness of the specific nature of the damage we do to the environment and of opportunities for remedial measures we can undertake locally as individuals or communities which, cumulatively, will have beneficial regional and global effects.

Conservation of existing buildings.

2.2.1

URBAN IMPACTSECOLOGICAL FOOTPRINTIntegration of public transport within new development.

The ecological footprint is a measure of sustainable development by which categories of human consumption are translated into areas of productive land needed to provide resources and assimilate waste products. Included in the calculations of the ecological footprint of a community, are the volumes of imported raw materials, food and fuel, taking into account land, water or air used for production or waste disposal. Cities in developed countries generally have a much larger ecological footprint than those in developing countries. For example, the average ecological footprint in Italy is 4 ha/person, representating 320% of the land available in Italy, while Switzerland and Germany have ecological footprints greater than 5 ha/person. Londons ecological footprint is almost equivalent to the entire area of Britains farmland. By comparison, the worlds average ecological footprint is 2.4 ha/person. [4] 2.2 URBAN HEAT ISLANDS

Our aim should be to promote sustainable urban developments which are designed in response to the climatic, topographic and environmental characteristics of a site, protecting its natural features and promoting an efficient, prudent use of resources.

A heat island is an area of land whose ambient temperature is higher than the land surrounding it. Many studies show a direct correlation between the density and population of a city and the intensity of the heat island effect. Higher urban temperatures increase the demand for electricity for cooling and air conditioning in warm conditions which leads to an increase in the production of carbon dioxide and other pollutants. These pollutants in turn contribute to increasing global temperatures due to the greenhouse effect.

Ecological Footprints per person in Canada [3] Ecological Footprint hectares per capita Housing 0.89 Transportation 0.89 Consumer Goods 0.89 Services 0.3 Food 1.3 (0.02 vegetable and fruit) Total 4.27

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Some of the main factors contributing to increased temperatures in urban areas are: air pollution and heat production from buildings and traffic; building and other hard surfaces which absorb solar radiation and reflect heat; reduction in airflow and humidity caused by the sheltering effect of buildings.

Temperature

High point

Base temperature

Urban heat island effect.

2.3

BUILDINGS AND LAND USE

Buildings are required for almost every activity and are the principal elements of the urban fabric. There are environmental impacts associated with their construction use and disposal. Land use for buildings and other purposes is a scarce, finite resource that has hitherto often been used wastefully, especially in and near cities and towns and in suburban areas. Future sustainable development needs to address land use and planning according to function to ensure that optimal use is made of the available land resource to serve the needs of society as a whole. Issues of sustainability associated with buildings and the land they occupy are discussed in detail in the following pages.Traffic congestion in Dublin.

2.4

TRAFFIC

Too many cars on streets

Traffic congestion reduces the quality of life in cities, wastes time and energy, and increases environmental degradation. The design, placement and density of buildings in an urban environment have a great influence on the consequent transportation patterns. The prolific use of the private car is both a cause and result of inadequate public transport facilities in many European cities.Increasing traffic congestion

Less use of public transport

2.5

WASTES (SOLID, LIQUID, GASEOUS)

Slower mass transport less mobility reduced service

The domestic, commercial and industrial waste generated by urban living are of concern to local authorities and inhabitants and a major source of environmental pollution. The smells and other emissions associated with sewage treatment plants and landfill sites, traffic and industrial processes are a regular source of irritation, particularly where large numbers of people live close to such pollution. 2.6 WATER QUALITY

The quality of our water is influenced greatly by human development. Acid rain is a common problem in and downwind of urban communities and industrial facilities. The expanse of hard impermeable surfaces in cities results in large bodies of rainwater requiring collection and discharge elsewhere. Dust, dirt and other solid pollutants are washed with rainwater into drains, the water sometimes discharged untreated into local waterways. Drinking water from local waterways often requires treatment with chemicals to combat bacteria and other micro-organisms from such pollution. 2.7Impermeable city surfaces.

AIR QUALITY, OZONE DEPLETION, GREENHOUSE GASES, SOLAR RADIATION

Many cities have succeeded in reducing the high levels of pollution traditionally caused by large-scale fossil fuel combustion. In London prior to the 1956 Clean Act, air pollution had reduced midwinter solar radiation in the city by 50% compared with the surrounding countryside [5]. The suns capacity to contribute to thermal comfort in winter was thus halved. Today, vehicle use is one of the main contributors to air pollution in cities. Despite reductions in individual vehicular emissions, the increasing number of vehicles on the roads in cities ensures the continuing rise of urban air pollution levels. 2.8 AERODYNAMIC IMPACT Wind velocities in cities are generally lower than those in the surrounding countryside due to the obstructions to air flow caused by buildings. Wind affects the temperature, rates of evaporative cooling and plant transpiration and is thus an important factor at a micro-climatic level. Built-up areas with tall buildings may lead to complex air

Smog over Paris.

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movement through a combination of wind channelling and resistance, and this often results in wind turbulence in some areas and concentrated pollution where there are wind shadows.

600 500 Altitude 400

Windspeed : m/s 40

40 30

300 200 20 100 0 20 30 20 30 40

In older settlements and mediaeval towns, low buildings following curved street lines result in low wind velocities at street level. Contemporary cities populated by high-rise buildings experience down draughts on windward faces and suction on lee faces causing turbulence at ground level particularly around corners, through arcades, building openings and passageways.

Wind speed at a given height, is lower in towns than over open land.

2.9

URBAN DUST

Urban dust is particulate matter released into the air as a by-product of building works, exhaust fumes from buildings and vehicular traffic, manufacturing and other processes. It clings to porous surfaces such as stone, brick or concrete. The streaking effect under windows and architectural mouldings is a result of this dust being washed off non-porous surfaces such as glass, and lodging itself on the porous material below. Extensive sealed surfaces and insufficient planted areas intensify this problem. Apart from the aesthetic effects of urban dust, studies have shown that excessive exposure to this dust may aggravate pulmonary disorders.

Stone decay in Dublin.

3.

URBAN DESIGN STRATEGIES

Environmental strategies for sustainable development should be based on an understanding of the climate, geography, culture and traditions of a location, combined with knowledge of best practice experience and innovation. Such contextual influences have been implicit in traditional landscapes, settlements and lifestyles, and they often continue to serve as exemplars, although technological developments can offer solutions hitherto unavailable. Sustainable urban design and planning should promote an environment which offers: Diversity - allowing variety, flexibility Comprising a mix of different building types, activities and social classes and considering the 24 hour occupation of urban areas Developed around green spaces with a diversity of flora and fauna species Utilising a range of energy sources (primarily renewable) thus reducing dependence on a single resource Productivity - efficient, closed-loop production In the near future building-integrated systems, such as photovoltaics, heat recovery, water recycling and solar thermal, will give every urban block the potential to produce energy and water both for its own use and to contribute to urban networks of energy production. This use, recovery and reuse could reduce the demand on electricity grids and water supply networks Through resource use minimisation, reuse and recycling, waste can be largely dealt with within city boundaries and the environmental impact of urban developments contained Protection - mitigating climatic extremes Bioclimatic, ecological planning and design can offer a means of climatic moderation to benefit people, flora and fauna in urban settlements Strategies include optimising solar energy, wind and acoustic sheltering, natural cooling, groundwater management and vegetative pollution filters Natural shelters (e.g. tree shelter belts) can create climatic buffer zones between differing land usesTraditional sustainable design.

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Site planning aims: Maximise the potential for passive solar gain in winter Allow solar access at street level, appropriate to the climate Enable a degree of freedom in placing buildings on plots without causing excessive solar obstructions to/by adjacent buildings Use street proportions and external landscaping features which take into account variations in climate and sun angles occurring across Europe

3.1

SITE SELECTION AND ORIENTATION

Solar access should be a principal influence on the planning of any development. Consideration must be given to the need for heating or cooling and to daily and seasonal variations in solar radiation and wind flows, which will determine the relative importance of solar and wind strategies. These factors vary across Europe; for example, in northern Europe the sun is at a lower angle for any given time of the year, causing longer shadows, and more solar radiation is desirable in buildings there than in countries further south. Daylight penetration and thermal comfort within any built environment are largely the result of the buildings exposure, and these are influenced by: Orientation In relation to the suns daily and seasonal movement, and wind flows. North-South orientations are generally preferable to East-West facing buildings, where excessive solar gain may be problematic. Form The design, relative size and glazing ratio of each facade can play a major role in the energy efficiency of a building. Surrounding terrain Topography, windbreaks and surface roughness determine protection or exposure. Adjoining developments In general, denser developments result in a greater reduction in wind speeds but proportionally increased turbulence. The edges of built-up urban areas in particular need protection from prevailing winds and driving rain in northern Europe. Consideration must be given to optimising the solar access of any site, particularly as passive solar technologies become increasingly common in urban situations. Where solar gain is desired (during the heating season, for example) adjacent structures or vegetation should not be permitted to obstruct sunlight. The planning of access roads on a site influences solar access considerably by determining plot orientations, particularly on smaller sites. Roads laid on an east/west axis, with smaller north/south links where necessary, are most conducive to southerly oriented buildings, but this may not be viable in every situation.

High altitude siting.

Optimal siting: Cool climate low to mid slope to avoid strong winds and cool air pockets Temperate mid slope preferable to exploit summer breezes, upper and lower slope also possible when sheltered from prevailing winds without compromising the benefits of summer breezes Hot arid high altitudes preferable above sloped ground to benefit from cool air flows Hot humid high altitudes on windward side to increase evaporative cooling potential

N

E N W S 5 W S

N E W 5 E

S

(I) Standard house 0 inclination

(II) North facing slope 5 inclination +400 kWh/year

(III) South facing slope 5 inclination -150 kWh/year

Secondary access road

In a typical residential development with houses at 21m spacing, compare the heating requirements of the same house on: (i) flat ground (ii) a 5slope, north facing (iii) a 5slope, south facing.Primary access road N

Common planning constraints: Site topography (steep contours, water courses, geological characteristics, patterns of water run-off) Landscape features and obstacles Existing roads, buildings and infrastructure routes Planning and building legislation (setbacks, plot ratio, site coverage, rights to light, emergency services access) Where such constraints require roads to be on a north/south axis, innovative design and configuration of buildings within urban plots can help ensure adequate solar access. Considerable tolerance in orientation (+/- 30 of south) is possible and the use of appropriate building forms can result in successful, climate-responsive buildings.

Providing secondary access roads along east/west axis giving buildings side-entry and side-gardens. This can create open spaces serving as solar / thermal buffers in front of buildings.

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In developments with a mix of building types and forms, buildings should be arranged with respect to the suns path and orientation of the site. Taller buildings should be placed to the north of lower ones, at site boundaries or corners surrounded by roads, where they cause least solar obstruction and overshadowing.Varying roof profiles across a site helps to increase the number of buildings with good solar access. Grouping and spacing of buildings should be designed to prevent undesirable windtunnel effects.3

1 roof 2 south facing glazing 3 south facing external space 4 north elevation 1

4 2

Southern European site layouts should aim to optimise natural cooling. Building forms and densities can be designed to optimise shading. The cooling potential of wind flows across a site should be considered at the early stages of a design. Air movement up or down a slope can significantly influence cooling. Anabatic flows, where air is warmed by the ground on a calm, sunny day, rise up a slope. Katabatic flows, where air is cooled by the ground on a calm, clear night, move downwards and have more noticeable effects, creating cold pockets in hollows or valleys and aggravating frosty conditions due to trapped cold air. As pressure on land for development increases, designers are often faced with sites in ecologically sensitive areas or on difficult soil conditions. Such developments, if they are to occur, require especially careful design to minimise environmental impact, particularly in terms of ground and surface water conditions. Sites located near wetlands, for example, should limit water run-off to avoid disrupting salinity levels, water-based wildlife and vegetation. 3.1.1 Case Study ParcBIT Project, Mallorca As part of the EXPO CITIES project in the Balearic Islands, the architectural firm, Richard Rogers Partnership, together with a multi-disciplinary design team, has provided a masterplan for a new sustainable community near the capital city of Palma. As a residential community of 2,500 people with a peak working population of 6,000 people, ParcBIT is intended to be a business and science park set within the context of a full community development. The communities are arranged within three urban clusters each of which is in itself a village, and which together form a distinct balanced community. Each cluster gradually diffuses from a vibrant, publicly focused centre, through a working district of offices, production, manufacturing and housing to a quieter residential area on the outskirts. The proposal aims to maintain a balanced cycle of activities over the day and throughout the year. The phasing of the construction is structured so that each of the villages will grow from the core outwards, establishing life in the centre to form a focus for each village, preceded by the progressive laying down of infrastructure. Careful analysis of the site and its landscape has influenced the masterplan which is designed to preserve natural landscape features. The topography of the site has played a significant role in the definition of built form and circulation patterns. Buildings are located on terraces which wrap around a ridge following the contours of the land. Ten percent of the winter floodwater from two flood torrents traversing the site is to be collected in a storage area and released over the year to provide both irrigation and drinking water. Traditionally constructed buildings with thick masonry walls will help ensure that rooms are cool and comfortable. Height to width ratios for streets and squares are controlled to ensure good daylight penetration to buildings, while providing shade to public spaces in summer and allowing solar access in winter. Building facades are designed to open in summer to provide shade and ventilation to buildings and pedestrian routes, and when closed in winter provide a buffer zone. The energy strategy for the development proposes to reduce demand by 70% by constructing energy-efficient buildings and by using a combined heat and power system fuelled using renewable energy sources. An important part of the concept at ParcBIT is the proposed integrated transport system with trams, buses, and electric cars connecting each cluster with the university andSurfaces to consider when assessing solar access.

Most solar thermal systems in Europe are used for domestic hot water (DHW]; In NW Europe a 3m2 solar installation can provide up to 50% of average annual DHW demand. [6]

Objectives of ParcBIT project: To provide a masterplan for a highquality living and work environment To encourage state-of-the-art telecommunications technologies in a pilot community that offers solutions to the problems of modern urban living To make ecological concerns paramount in the design solutions To create a vibrant, publicly focused, compact urban community To use the naturally available resources on the site to create an enriched agricultural landscape

Model of ParcBIT, Mallorca.

Plan of urban clusters.

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Palma. A road-based tram system will serve 7,000 inhabitants and a further 5,000 people on the university campus. Green-planted cycle and pedestrian routes will provide access to residential areas from road and tram links. Parking areas will be located so that residents and office workers can share spaces, thus reducing the overall number of spaces required.

Energy strategy.

Bio-climatic design for buildings and open spaces in ParcBIT, Mallorca.Comfortable walking distances.

3.2A net density of 100 people per hectare [or about 40 50 dwellings] is recommended for neighbourhood developments on average in the UK on the basis that: [13]

DENSITY

3.2.1 Buildings The move towards revitalising and repopulating inner city sites with high density, mixed-use developments aims to improve the viability and vitality of urban centres, increase the potential for shared resources and reduce vehicle use generated by suburban dispersal. A sustainable approach to the issue of density reduces the dominance of the role of the car and instead considers less environmentally damaging ways of achieving the horizontal and vertical movement of people, energy, food, goods, water and waste. In general, developments with higher densities use less energy for horizontal movement: in mixed use developments most facilities can be located within walking distance or integrated within an efficient public transport system. Reducing travel distances will reduce car use and its related greenhouse gas emissions, allowing design strategies to focus on the needs of cyclists, pedestrians and the provision of green spaces between buildings. Higher density developments enable the sharing of facilities and resources. Infrastructure supply lines can be shorter, reducing distances for energy and water service runs. For maximum density developments containing high-rise buildings, the additional energy required for the vertical transfer of people and services such as energy, water and waste must be addressed. Moving infrastructure upwards against gravity requires more energy than horizontal flows. However, a higher density scheme will allow a greater area of land to be dedicated to landscaped public areas and activities, including allotments for food production and on-site bio waste treatments, for example. At an architectural level, the embodied energy of the building materials must be considered. High-rise structures often require materials (e.g. steel) with a higher embodied energy than traditional materials used in low rise construction. The optimum densities for mixed development of a site depend on variables such as climatic, social, and topographical factors, location and existing settlement. Fundamental to the success of any new development is planning foresight and wellprogrammed investment in high quality infrastructure and facilities. The potential disadvantages of high-density developments in terms of daylight access, wind tunnelling and urban heat island effects for example, can be mitigated by climate-responsive design. A starting point in any project must be to assess the microand macro-climatic characteristics of the site, an exercise which will indicate

it is the necessary density to support a good bus service it is the lowest density viable for district heating schemes it is the highest density capable of allowing good solar access with appropriate layout

Traditional inner city density.

Advantages of medium to high density developments: Increasing the density will leave more land for green areas within and adjacent to urban areas Schemes for food production at a community scale become feasible. Reduced travel distances favour cyclists and pedestrians District heating and cooling systems become more feasible where local sources of waste heat are available

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appropriate bioclimatic design strategies. Some basic considerations for developments in different European climates are outlined below: Cool climate Aim for optimum balance between maximum solar access and wind shelter Use vegetation to reduce heat loss in winter and at night Temperate climate Maximise solar access and natural ventilation potential in buildings Use vegetation for seasonal wind-shelter and solar shading Hot-arid climate Plan high-density developments which allow space for shaded external areas; e.g. courtyards Select vegetation appropriate to the climate for shading Provide adequate solar access in winter Hot-humid climate Plan high-density developments around shaded external areas conducive to a free flow of air Design buildings to facilitate natural air movement patterns Provide adequate solar access in winter 3.2.2 Case Study Kronsberg, Hannover Another example of an EXPO CITIES project, the new district of Kronsberg, Hannover, is being developed according to the International Council for Local Environmental Initiatives recommendations of Agenda 21, coordinated by the Kronsberg Environmental Liason Agency, with an ecological concept in the spirit of the Charter of Aalborg, which commits it to a new sustainable design approach. A mixed residential district of terraced houses and large and small apartments, will provide 6,000 dwellings for 15,000 inhabitants, almost half of whom will be living there by the opening of the EXPO in June 2000. Services and amenities for the new district will include a primary school, a schools centre and three kindergartens, neighbourhood parks, and reserved areas for social services and commercial uses. An Arts and Community Centre will house the city councils advice bureau, church and community centre, health centre, shops, cafes and restaurants. A grid layout incorporates avenues, parks, squares and planted courtyards, with each section of the district containing 1000 dwellings in eight blocks grouped around a neighbourhood park. It is a high-density development respecting the principles of efficient resource and land-use. There will be three zones from west to east with differing levels, density and dwelling types; four storey apartment buildings to the west next to the service road and tram route; three storey housing in the middle; and two storey terraced housing to the east. Ten per cent of the housing will be owner-occupied; the remaining ninety per cent will be subsidised rented accommodation. All of the dwellings will have direct access to a green space in the form of a courtyard and nearly all of the dwellings will have a private garden, a balcony or a roof garden. The landscape plan for Kronsberg incorporates the planting of woodland on the Kronsberg ridge with diverse habitats created in the vicinity for wild plants and animals .Residential district at Kronsberg.

Mutual shading.

New forests planted in four year rotations of fast growing willow or poplar within a framework of mixed hardwoods, whose timber can be used as a substitute for coal, could reduce the amount of carbon in the atmosphere by 3 tonnes/hectare per year. [7]

Commercial development at Kronsberg.

Extensive commercial estates are being developed directly adjacent to the residential district, fulfilling the aim to develop workplaces close to home, accessible by public transport. The long-term planning aim is to expand the current commercial development to the south after EXPO 2000. The simultaneous realisation of the residential area with its infrastructure and amenities, comprehensive landscaping and green space, constitute attractive conditions for the location of businesses and employment. A new tram service connecting Kronsberg to the city centre will have a journey time of 20 minutes, with sufficient tram-stops to ensure that no dwelling is more than 600m from a stop. The main service road runs parallel to the tramway on the edge of the residential area to minimise disruption. From the main service road, the district has a network of minor streets, serving only local traffic, bordered with trees and grass verges. The streets are laid out to favour pedestrians and cyclists. Car parking

Transport route, Kronsberg.

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requirements in Kronsberg have been set at 0.8 parking space per dwelling, much of it located in underground car parks. 3.2.3 External Spaces Much research has been done on the psychological benefits of comfortable external spaces and how these can be influenced by climatic, spatial and architectural design parameters. Social issues such as maintenance, security, and visual privacy or openness must also be addressed when designing external spaces.Climatic considerations to be addressed in providing comfortable external spaces include solar and wind access and proximity to sources of noise or air pollution.Solar houses, Kronsberg.

The most significant benefits of climate control are usually gained from localised features such as courtyards, sheltered or shaded areas creating microclimates more comfortable than surrounding public open spaces. Thus when considering climate and air quality at an urban scale, the provision of a network of many small green spaces or urban forests throughout a city is often preferable to a few large parks. Derelict land in cities may be reused to provide community forests and parks, climatic shelter belts and buffer zones, and visual and acoustic screening of motorways. 3.2.4 Case Study - Urban Parks in Paris Paris has many large and small public parks and gardens. As part of the regeneration of disused and derelict parts of the city, three new parks have been formed; the Parc de Bercy, the Parc Andr-Citron, and the Bastille Viaduct. Filled with vegetation, from mature trees to flower beds, these amenity spaces improve the immediate and general environment through the provision of natural air filtration mechanisms, water retention areas, summer shading canopies, as well as habitats for the areas local fauna.

External space, Berlin.

Parc de Bercy, Paris.

Parc de Bercy, Paris.

Bastille Viaduct, Paris.

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Parc de Bercy is built in the centre of a former wine quarter in the east of Paris. Much of the area was derelict and in need of renovation. The park was designed by Bernard Huet and FFL architectes, and encompasses an area of 14 hectares. It is divided into three rectangular sections: an open grassed play area, containing trees informally interspersed within an orthogonal grid of paths; a central garden section, subdivided into regularly planted and shaped plots, and traversed by a canal which leads to the third, water section of the park. A raised walkway, designed to act as a

visual and noise buffer to the nearby motorway was also planned but financial constraints have prevented the construction of this part of the development. Parc Andr-Citron is located on the site of the former Citron car factory in the west of Paris. Gilles Clement and Patrick Berger designed the northern sector and Jean Paul Viguier, Jean-Francois Jodry and Alain Provost were responsible for the southern part. The park covers an area of 14 hectares, and is centred around a large green expanse of grass. Geometrically sculpted gardens contain and control the vegetation. Each garden has a different theme: deciduous trees are scattered throughout one garden; another contains a pattern of evergreens; yet another is left to grow wild. A terrace of fountains saturates and cools the paved area between the orangeries, while a row of limestone pillars containing small water fountains lines the western end of the park. The Bastille Viaduct is an example of the advantages of reusing existing urban fabric to improve a local environment socially, economically and environmentally. A disused viaduct was renovated to provide an elevated linear park, along which runs a promenade lined with trees and other vegetation. Patrick Berger was the architect responsible for the design of the renovation works, comprising the viaduct, the 13 hectare park above, and shops under the arches of the viaduct at street level. 3.3 CLIMATE OPTIMISATION

Bastille Viaduct, Paris.

SPECIES

SOLAR RETENTION % 88.6 85.8 91.0 83.6 90.1 87.0 93.8 89.0 89.0 89.1 91.4 77.5 91.6 89.8 90.6 85.8 85.8 94.3 86.0 93.2

3.3.1 Solar Radiation The aim when addressing solar access to any development is to design for maximum desirable solar radiation when heating is required, while protecting against unwanted solar radiation when overheating may occur. Maximising solar access is generally desirable in northern latitudes, while in southern latitudes protection from excessive solar access is generally required in summer. Deciduous trees are particularly effective seasonal shading devices, providing protection in the summer months while allowing daylight and solar penetration in winter. Where sunlight reaches ground surfaces directly (plazas, wide streets) vegetation can be used effectively as a means of solar shading (trees and shrubs) and absorption (grass).COMPARISON OF TREE FORMS: Y2 < Y1 AND X 2 > X1 ,WIDE, SHORT TREES GIVE BETTER SHADE PATTERNS BOTH SUMMER AND WINTER

Acer Negundo Catalpa Bignoinoides Celtis Australis Ceratonia Silicua Cercis Siliquastrum Citrus Aurantium Ficus Macrophilia Gleditsia Triacanthos Ligustrum Japonicum Melia Azedarach Mioporum Pictum Morus Alba Nerium Oleander Olea Europea Phoenis Dactilifera Pinus Alpensis Platanus Acerofilia Populus Alba Bolleana Robina Pseudoacacia Sophora Japonica [8]

AL WINTER SHADE

Y1 X1

Y2 X2Seasonal shading, Dublin.X : BENEFICIAL SUMMER SHADE Y :DETRIMENTAL

The main considerations in the design of planting are species type, growth rate and location. Different species of vegetation have different capacities to absorb solar radiation. Local species generally have stronger resistance to local pest and climatic conditions, requiring less maintenance than exotic species. The characteristics of plants that can significantly affect their contribution to solar shading are: Growth pattern the time taken for sufficient growth to provide shade/cooling benefits Diameter and height implications for tree-spacing, distance from buildings, extent of shadows at maturity Duration of leaf season timing relative to the heating/cooling season, implications for solar access and the appearance of the trees in winter

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Pollution resistance durable species are needed in urban areas to avoid premature plant death When planning trees near buildings, consider crown diameter and height relative to the location of solar collectors and windows. Trees in sheltered locations retain their leaves for longer, which may or may not be desirable depending on the climate and solar access requirements.Green spaces provide shelter, shade and a more pleasant environment. Gardens and living spaces are oriented south to maximise light and heat to living areas and to garden.r sun

N

Winte

45

45

Selective tree siting to maintain solar access.

Service and circulation spaces are to the north of the house and act as thermal buffers. Prevailing winds

Swiss municipalities are encouraging the planting of existing flat roofs. In Bern, a law has been introduced requiring the provision of planted roofs on all new construction or existing buildings undergoing retrofitting.

GREEN SPACE

ACCESS ROAD

HOUSE AND GARDEN

BUFFER SPACE

MAJOR ROAD

Deciduous planting provides shade in summer and allows light to penetrate in winter

Planting and landscaping act as insulation and shelters against motorway noise and pollution, and prevailing winds.

Roof gardens can be established on the flat roofs of buildings using potted trees, shrubs and plants. Roof planting also reduces the area of roof surface exposed directly to the sun and the summer and winter temperature extremes to which a buildings roof structure is subjected. Planted, or grassed roofs, though not common, are beginning to be found on buildings in urban centres across Europe. Low maintenance grass roof systems are increasingly available. Some of the benefits include: Improved thermal stability of building structures and, consequently, interiors Reduced thermal stress in roofing materials, which extends their lifetime Acoustic insulation from the additional roof mass A natural habitat for species is created in an often otherwise hostile urban environment Up to 50% reduction in rain water discharge from roofs due to vegetation retention and evapo-transpiration of water Reduction of the urban heat island effect through the absorption of solar radiation by vegetation Replacement of green space lost to the buildings footprint 3.3.2 Wind Wind velocities have a significant impact on thermal comfort in urban microclimates. Although average wind velocities in cities can be as little as 50% of those over open water, tall buildings separated by open spaces can create local turbulence with implications for driving rain and drifting snow. In cool climates and locations subject to high winds, vegetation can be used as a wind break, reducing excessive wind speeds, yet allowing enough air flow through external spaces. Dense planting around narrow openings in the urban fabric will mitigate wind-tunnel effects, impede the movement of dust and improve thermal comfort within surrounding buildings by reducing fabric heat transfer and infiltration. To reduce wind speeds so to provide shelter: Configure buildings to give wind protection without creating tunnels Use wind shelter belts (vegetation or architectural elements) to provide protection from prevailing winds Plant a mixture of high- and low-branching trees and shrubs, to reduce wind speeds at different levels Provide protected public spaces, using earth berms or changes in ground levels, for example

Green roofs, Vienna.

Roof ponds are an alternative to planted roofs, covering entire roof surfaces or incorporated within roof gardens, especially in warm climates. They provide a thermal mass which helps stabilise roof temperatures, and, through evaporation of the water, provides cooling.

Turbulant wind conditions around tall buildings.

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By placing trees along promenade, wind tunnelling is avoided and summer evaporative cooling is provided creating a protected microclimate.

Landscaping elements used to obstruct the path of the winter wind through public spaces

1. Orientate long axis parallel to dominant wind

evaporative cooling from river

2. Avoid large flank walls facing dominant wind

Urban heat stored in landscaping mass dissipates, and is replaced with cooled external air, thus inducing natural ventilation in buildings.

To increase wind speeds, promoting natural ventilation: Use vegetation, architectural elements (screens, walls, buildings) and configuration of streets and buildings to direct prevailing winds where needed while not obstructing desirable summer air flows Limit the use of low-branching trees and shrubs Locate public spaces where they will benefit from katabatic air flows down valleys and slopes 3.3.3 Temperature Evaporative cooling has been used to reduce temperatures locally in Southern European countries for centuries, from the Gardens of Alhambra to the 1992 Seville EXPO. Water evaporation absorbs a considerable amount of heat energy 590 calories per cubic cm of water evaporated. Direct evaporation of water raises the moisture content of surrounding air, from bodies of water, fountains or evapo-transpiration of vegetation, inducing cooling of the air and adjacent surfaces. Passive direct evaporation strategies at an urban scale can be achieved by simple means, such as the provision of vegetation, fountains or ponds in public spaces, or by more complex means such as water towers. When using evaporation in hot climates an expansive surface of water is not needed but natural ventilation should be designed to avoid problems with increased humidity levels. Indirect evaporation avoids problems with humidity levels and does not require as high a velocity of air flow as direct systems, although its use often entails a greater level of planning, design and equipment. Due to the evaporation of water from vegetation, temperatures can be up to 10K lower in urban parks than in surrounding densely built areas (see section 3.3.6). Alternating densely planted areas with open spaces enhances night cooling, by allowing the humid air from around the vegetation to escape. Concentrated sources of heat production, e.g. kitchens or plant rooms, should be located near densely planted areas. The presence of a body of water will help to moderate temperature extremes due to its high thermal storage capacity. Evaporative cooling is most effective downwind of a cool, dry air flow, seen in many traditional settlements in hot-arid climates which feature ponds or wetted surfaces placed along known air-paths. The temperature of hard landscaping materials can be lowered when water is sprinkled, run over or through them. This is especially beneficial in built-up areas with large surfaces of heat retaining materials, exposed to high solar radiation. To increase air temperatures at a site: Optimise solar exposure and create `sun traps on south-east to south-west facing sites Provide windbreaks to direct cold air flows away from open occupied spaces and buildings Use dark coloured heat retaining materials (concrete, masonry) on south facing surfaces

3. Avoid funnel-like gaps between buildings

4. Avoid long, parallel rows of smooth faced buildings.

Evaporative cooling, EXPO 92, Seville.

Evaporative cooling, Sydney.

Opportunities for integrating vegetation within urban developments: Public and semi-public open spaces: plazas, squares, courtyards, passageways, arcades and other spaces between buildings at ground level Private gardens, courtyards, building plots and allotments Alongside roads, paved streets, pedestrian streets, motorways Down the centre of roads and motorways Roof gardens Pergolas Planted roofs Planting applied to vertical building surfaces as organic facades

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To decrease air temperatures:Over one day, a single, large tree can transpire 450 litres, diverting 230,000 Kcal of energy away from raising air temperatures, equivalent to five average air-conditioner units running for 19 hours each. [9]

Use vegatation for solar shading, particularly in summer Site any wind shelter belts to avoid impeding air flows, use only branching trees Provide measures for evaporative cooling Limit the amount of exposed hard landscaping materials and use ground cover vegetation extensively

3.3.4 Relative HumidityTo increase humidity at a site: Increase the water retention of surfaces and reduce drainage Provide a means of evaporative cooling using fountains, ponds, sprinklers and sprays for example Use vegetation in preference to hard landscaping materials where possible Use low planting to reduce moisture evaporation from ground

In landscaped urban areas the evapo-transpiration process of plants influences the relative humidity and air temperature. Relative humidities under planting or dense trees can be 3% to 10% higher than in unplanted areas [10]. As the level of evaporation is directly proportional to the density of vegetation, leaf surface-to-air temperature and relative humidity of the air, effects are greatest in hot dry summers, and least in winter. Studies have shown that for mid-European latitudes, if at least 20% of an urban area is planted, more solar radiation is used to evaporate water on the leaves of the plants than to raise the temperature of the air, providing an effective natural cooling strategy. [9]. 3.3.5 Air Quality Plants and soil survive through the exchange of light, water and gases. In areas where air quality is poor, many species of vegetation can absorb substantial levels of common urban pollutants such as CO2, NOx, SO2. Some plants are not only resistant to air pollution, but can significantly improve the local air quality by filtering particulate matter from the air through their leaves. A Douglas Fir, for example, with a trunk diameter of 38cm can remove 19.7kg of sulphur dioxide per annum, without damage to itself, where atmospheric pollution is around 0.25 p.p.m. [9]. Deciduous trees have the added advantage of a seasonal replenishment of their leaf supply, with which to filter the air. Consider planting near or downwind from sources of dust or pollution such as motorways and dry and dusty ground surfaces. 3.3.6 Case Study EXPO 92, Seville One of the main aims of the designers of the 1992 Seville EXPO was to provide a comfortable external environment in which the estimated 290,000 visitors per day could relax between visits to over a hundred international pavilions on the site. The area of the EXPO site was 215 hectares with pavilions taking up an area of 50 hectares, leaving three quarters of the site as external spaces. A master plan was devised for EXPO 92 by a team of architects, planners and local authorities which established criteria to achieve a bio-climatic, ecological framework for the development. Fundamental to the development was the provision of the most comfortable external conditions possible through natural and passive cooling measures using vegetation and water. Extensive planting of vegetation took place very early in the process to provide sufficient time for plant growth before the opening of EXPO. The pavilions were grouped to allow the public open spaces to give a sense of unity to the site while providing external spaces for restaurants, meeting and resting areas which could be bio-climatically controlled. Reductions in outdoor air temperatures of up to 10K were claimed. The ratio of soft to hard landscaping was proposed at 60:40, with vegetation integrated with the built areas as much as possible. Vegetation species of different heights were used to maximise the filtration of air at different levels. Planted screens were designed to channel prevailing winds into the site, enhancing their cooling. Water was used throughout the site in fountains, water walls, sprays, cascades, ponds. Studies prior to the construction of the EXPO, and further in-use assessments have shown that comfortable external environments were achieved by the natural means described above when climatic conditions in Seville remained below the following levels:

Vegetation absorbs ozone, sulphur dioxide, carbon dioxide, and other polutants, reducing the amounts present in the atmosphere Soil micro-organisms are particularly effective in contributing to the conversion of carbon monoxide to carbon dioxide Plants placed at roadsides release oxygen which combines with nitrogen oxide to form nitrogen dioxide, which is again absorbed by plants

Bio-climatically controlled spaces, EXPO 92, Seville.

external

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Relative humidity 40% and Max. temperature = 36C Relative humidity 60% and Max. temperature = 30C* *with minimum wind speeds of 1m/second.

Strategies used for microclimate control throughout the EXPO 92 site include the design of: Vegetation Shading Ventilation Water evaporation Thermal inertia of the ground, landscaping features Heat dissipation systems Air filtration systems

Shaded pedestrian routes, EXPO 92, Seville.

3.4

BUILDINGSEXPO 92, Seville.

3.4.1 Building Materials A buildings envelope not only acts as a climatic filter determining internal comfort but, due to its thermal mass, solar reflectance and transmittance, also influences thermal and visual comfort conditions in adjacent external spaces. Building materials exposed to direct solar radiation will store this as heat which is released after a time period depending on the reflectance and heat storage capacity of the material. At an urban level this can be an advantage in contexts where a delayed release of stored heat will benefit external spaces used in the evening time. In hot climates, light coloured, reflective surfaces are preferable for reducing the heat gain of a structure by day, but care should be taken to reduce exposure to glare caused by light reflected off these surfaces, and glass facades in particular. Using dark coloured finishes to reduce glare may result in an increase in the solar heat gain of the structure, which can in turn increase the cooling load of the building. The use of vegetation and architectural features to providing shade in such situations may be more appropriate. Vertical and horizontal shading can shield large surfaces of a facade, offering solar, wind and rain protection. In cold climates where solar heat gain by day is beneficial for evening heat release, south facing walls can be covered with deciduous vegetation to avoid obstructing desirable solar gain in winter. Conventional dark coloured roof finishes (asphalt, PVC, EPDM) absorb large amounts of solar radiation especially in summer. Lighter coloured or reflective finishes, grassed roofs and roof gardens can significantly mitigate heat gain. 3.4.2 Building Form and Construction Optimum building forms vary according to climatic parameters and can have a profound impact on the form of urban spaces. In all climates, building design should aim to maximise daylighting, energy conservation, and shelter (solar or wind shelter, depending on the climate). In general compact building forms are preferable. By minimising the surface to volume ratio, heat losses and gains can also be minimised. Building construction with a high thermal mass can be beneficial in both cool and hot climates. The thermal stabilty provided by high mass construction contributes to slower heat transfer in hot dry climates, while in cooler climates, solid construction exposed to winter sun can act as a heat sink. The use of light colours on external finishes reduces thermal gains in building envelopes, but consideration should be made to avoid problems with glare.

In general, construction materials should be: appropriate to the climate preferably indigenous of low embodied-energy recycled, recyclable, non-toxic dependant on local skills

Appropriate light-coloured reflective facade in hot climate.

Workshop

Bath BUFFER SPACES Bedroom Hallways, Storage, Stairs, etc.

Bath Bedroom Living Area Kitchen / Dining

N

S

Location of indoor spaces.

15

Buildings should be designed to encourage natural ventilation in the summer months while providing wind shelter in winter.In all climate zones it is beneficial to zone activities within buildings according to solar and wind exposure, daily and seasonal occupancy.

Zoning rooms to provide thermal buffers can benefit both hot and cool climates. In Northern European climates, buffer zones located to the north of buildings prevent excessive heat loss, while in the warmer southern European climates uninhabited rooms to the west of buildings provides a thermal buffer against low afternoon sun. 3.4.3 Case Study - GREEN City; Radstadt, Austria The European GREEN (Global Renewable Energy and Environmentally responsible Neighbourhoods) Cities project, supported by the EU Thermie programme, included eleven low-energy residential projects in seven EU Member States: Austria; Belgium; Denmark; France; Italy; Spain and the UK, and involves the planned construction of over 900 new dwellings. The main purpose is twofold: to initiate low-energy and environmentally sound housebuilding practice in these cities using best available technologies in new-build and retrofit projects based on energy and environmental assessment; and to provide information and demonstration of this practice for city authorities, builders and consultants. A special design tool was developed and is being used throughout the project, which assesses, from an economic viewpoint, the implementation of different energy-saving measures in the new and retrofitted buildings. Some of the sustainable building measures to be carried out include: Reduced ventilation rates achieved by improved ventilation design and the use of low-emissivity building materials Integrated solar heating design, PV solar energy for ventilation and optimised energy supply systems with an Energy Management Control System Sustainable low energy design which aims for: - 40 60% energy savings for space heating and hot water - 30% saving on electricity use - 30 40% saving on water usage Monitoring programmes which will be carried out for all the projects

GREEN City Project Planning Principles Sustainable urban planning Sustainable and healthy building design Energy and environmental assessment Optimised energy and water supply systems Building-integrated solar energy design

Cavity wall construction, Radstadt.

In the 13th century city of Radstadt, fifty new dwellings were planned, of which thirtysix have been completed. This solar low-energy development has become a model residential area, giving new identity and an improved quality of life to one of the oldest parts of Radstadt. Optimisation of the micro-climate and passive solar design were major objectives in site selection and building orientation. A primary aim was to minimise the total energy consumption for both construction and operation of the buildings. Life-cycle environmental impacts of ten construction methods and heating systems were undertaken to determine the most cost-effective, environmentally acceptable systems. To achieve low-energy buildings standards, the walls to the north, west and east are constructed of brick cavity walls with 160mm insulation, and to the south of lightweight timber construction. The design U-values of 0.2 W/m2K for walls and 0.7 W/m2K for windows respectively indicate the high thermal standards applied. The project is served by 108m2 of solar collectors for hot water, while a wood-chip fuelled district heating system and a heat recovery ventilation system help ensure low energy consumption. The total energy consumption for heating and domestic hot water for an average multi-family house is 76kWh/m2/yr; 14kWh/m2/yr provided by solar energy and 62kWh/m2/yr by biomass.

Light-weight Radstadt.

timber

construction,

3.5 RESOURCE MANAGEMENTWaste management strategy: 1. Reduce waste at source 2. Sort wastes 3. Re-use/re-cycle 4. Dispose of waste safely [11]

3.5.1Energy and Resource Management The efficient management of energy and other resources is of great importance in any sustainable urban design strategy. Minimisation of activities and functions that waste energy and resources is a primary consideration where effective action can result in a much smaller energy and resource supply task.

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While energy and resource optimisation at the scale of the individual building or other facility is important and the cumulative effects of such measures can be large, there are many energy and resource supply measures that are often best undertaken at an urban scale including: district heating systems; large-scale photovoltaic energy generation; large-scale combined heat and power production (eg using biomass as a fuel), wind power, and hydro-electric power production. 3.5.2 Waste Management The provision of adequate storage is necessary for different categories of waste, particularly for domestic waste in high density residential developments. This includes recycling collection points and communal waste-disposal areas. Particular attention should be paid to construction wastes and the potential for re-use of materials ranging from formwork to top-soil. Designated access routes of adequate dimensions for waste collection vehicles must be provided. Strategies for as much on-site treatment of waste as possible should be established, to reduce transportation energy costs and minimise landfill. Communal strategies for waste collection and treatment must be managed properly and supported by a large enough population for the process to be feasible. For example, the scale of waste combustion operations must be large enough to meet the cost of efficient, environmentally acceptable waste treatment equipment and controls which minimise the level of pollutants emitted into the atmosphere.

Photovoltaic application.

The principle of a CHP plant.100 m3

Volume of water used by...

...2 persons living in 40 m2 apt. per year

3.5.3 Water Management Strategies with regard to water use should promote sustainable water management, reduced consumption, water conservation, and the re-use and efficient treatment of water. Efficient removal of surface water (street drainage) and the high run-off coefficients of hard landscaping materials in contemporary cities reduce the amount of water retained on or in the ground with effects on drainage, vegetation, soil stability and oppurtunities for natural cooling through evaporation. Whilst the use of water features (fountains, ponds) for natural cooling is most effective in high temperatures, increasing ground water retention within urban areas will be of benefit in most climates by addressing the important issue of water management.

Reed bed, Earth Centre, Doncaster.

Typically, households require 30 to 50 cubic metres of water per person per year for direct domestic consumption alone. [12]

Septic Tanks

Accidental spillage Leaking storage container Waste incinerator

Refuse dump Leaky sewer Well Water table River

Polluted groundwater

Water channeling as design feature, Copenhagen. Impact of poor waste handling on water resources.

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It is important to establish an efficient water conservation system. Even in countries with high rainfall, due to the inadequate provision of water storage, water shortages may occur during prolonged dry weather. A comprehensive analysis of precipitation and evaporation data for a site should be carried out at the early stages of a project. Rainwater Storage Strategies Below ground Underground tanks and lakes, effectively acting as thermal heat sinks, contribute to natural cooling within the immediate microclimate Above ground - Lakes, canals and reservoirs can collect rainwater whilst providing areas of natural habitats and amenity - Rivers and canals can form the edge of landscaped pedestrian routes, introducing a greater variety of vegetation into urban areas - Roadways and pavements can be designed to incorporate rainwater retention and infiltration systems e.g. using protected channels and soakaways to create small water-courses along urban routes Rainwater collected and stored may then be used for irrigation and other purposes, where water of potable quality is not required. 3.5.4 Light Pollution Measures to reduce light pollution in urban areas:Canal, Lucca.

Fresh water, Brazil.

Reduce the use of non-essential lighting (turn off neon signage or shop-window displays in the early hours of the morning for example) Where lighting is required for emergency, security or operational reasons, use energy efficient luminaires of the minimum necessary wattage and, where possible, shield fittings to avoid light spillage Infrared motion-sensor lights are successful in security applications and help to reduce electricity consumption On public roads, uniform lighting with a low glare co-efficient and fully shielded fixtures effectively pointed downwards reduce light pollution and through more efficient lighting, can provide safer road conditions Low pressure sodium lighting is one of the most efficient light sources and has a low operating cost. The bright yellow monochromatic light causes less glare than mercury vapour lamps which are commonly used for all-night lighting. 3.5.5 Case Study EXPO 2000 Kronsberg, Hannover An energy target has been set for the Kronsberg development, to reduce CO2 emissions by up to 60% through savings on heating, hot-water and electricity, but with no reduction in comfort. This will be achieved by optimising energy use in low-energy housing and the incorporation of renewable energy sources and innovative technolgies. A standard Low Energy House in Germany has an energy requirement of 70100 kWh/m2/yr. At Kronsberg, a maximum level of 55 kWh/m2/yr was established. Specific energy-efficient construction methods and the use of environmentally sound building materials are mandatory. All buildings are to be linked to a district heating system.

Sky glow at night.

Low-energy housing, Kronsberg.

In the Solar City part of the development, 100 passive solar dwellings and a childrens day-centre are to draw half of their heating requirements from active solar energy and the other half from the district heating network. Another 32 dwellings are to be constructed as passive solar houses to demonstrate a building standard that will enable the space heating to be reduced to 1520 kWh/m2/yr while significantly reducing energy needs for hot water and household appliances. A district co-generation plant will produce power and heat with reduced emissions. Photovoltaic cells installed on the roofs of the primary school and the community and district arts centres produce power for these buildings. Two wind turbines have been erected which will supply the electricity needs of 3,000 dwellings.

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Wind turbine, Kronsberg.

Waste Management Concept High priority is given in Kronsberg to waste-minimisation strategies. Strategies for minimising construction waste as well as household, commercial and industrial waste, were developed. Construction waste makes up 40% by weight of Hannovers waste. The City administration has made regulations obliging property developers to choose environmentally friendly materials, low waste building methods, and materials that can be recycled. The on-site sorting of building waste for reuse, is supported by Hannover Waste management. Waste avoidance is the key principle in household waste management. Retailers will minimise packaging, and the nearby Kronsberg Farm will sell its produce directly in the district. Pre-sorting of household waste into organic matter, paper, glass and packaging will facilitate recycling. Organic matter may be composted by each household, with help and advice from the Hannover Waste management and Kronsberg Environmental Liason Agency. Recycling banks near dwellings will substantially reduce waste collection (by about 75%) and will subsequently reduce householders waste collection charges. Water Management Concept The water management strategy for Kronsberg comprises three main principles: rainwater management reduction in potable water use awareness-raising programmes Rainwater from hard-landscaped areas is collected, filtered and redirected into the water features on site in a Mulden-Rigolen-System. In the community centre and school, rainwater is reused for flushing toilets, watering gardens and green areas. All new houses will be equipped with water-saving fittings (flow restricters and pressure regulators), contributing to an estimated reduction in drinking water use of about 26 litres per person per year. Residents are encouraged to save potable water. A public awareness campaign, incorporating exhibitions, leaflets and brochures, will promote water-saving strategies for residents. Training for water engineers and school teachers will also be provided. The value of water will be emphasised through school projects by primary school children. All the rainwater falling in the school grounds and from the grassed roof of the school will be collected and used for flushing toilets and to water the school garden. General Water Strategies: Follow natural drainage paths as closely as possible Minimise the use of impervious ground surfaces Facilitate the absorption of rainwater in the cleanest condition possible Provide for collection and storage of rainwater for irrigation and other uses Consider on-site treatment of grey waterPublic awareness campaign. Water conservation project. Sorting of construction waste.

Composting of organic waste.

Infiltration Strategy - the Mulden-Rigolen System: Rainwater falls towards open gulleys, which run alongside roadways and pavements, and is channelled into a grassed-over hollow (mulde) which acts as a filter Beneath the hollow runs a pebble-filled underground storage basin (rigole) into which the water seeps Some of the water is allowed to seep back into the ground to maintain the water table level The rainwater is gradually released from the basin into surrounding retention areas via a drainage pipe with a restricted-flow outlet Retention Strategy: Most of the water leaves the site at this stage, via the existing stream which runs through the site. Some of the filtered rainwater is collected in retention basins and fed to points of use for toilet flushing and irrigating landscaped areas

Water retention area.

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3.6Some European car parking requirements

TRANSPORT

spaces per dwelling UK & Ireland-standard 1.5 Germany-standard 1.0 Kronsberg, Hannover 0.8 DWM Terrain, Amsterdam 0.3

Whilst patterns of movement are influential in defining and sustaining a city, particularly in terms of integrating different areas within an urban settlement, modes of movement are a major source of environmental and social degradation, due to vehicle emissions and the loss of land to roads and parking facilities. An increase in sustainable mobility is needed. Sustainable mobility is the facilitation of transport which fulfils its economic and social functions while limiting its detrimental effect on the environment. This includes design and planning strategies which support and promote less environmentally damaging transport systems for people and goods. Often, this may involve urban zoning to reduce travel distances and the provision of facilities which encourage low or zero energy modes of transport. 3.6.1 Urban traffic control Developments should be planned and designed according to a road management hierarchy primarily favouring pedestrians and cyclists. Planning

Pedestrian45 40 35

Bus

Bicycle

Car

Underground

Time in minutes

30 25 20 15 10 < 450m faster to walk 5 < 250m faster to walk 0 0 1 2 3 4 5 6 7 8

10km+ faster by underground (or lightrail)

< 4500m faster by bicycle

9

10

11

12

Distance in km

Travel times from door to door for different modes of transport in urban areas. [11]

Incentives for using low-energy / zero-emission public transport: Cycle-path networks integrated with urban planning policies Providing municipal bicycles and low-energy vehicles for hire Adequate charging / fuelling stations for electric and biodiesel vehicles Restricted access for private cars within city centres and environmentally sensitive sites Public awareness campaigns and incentives

Development should be: located around or close to public transport nodes and frequently used routes planned around a network of pedestrian routes and footpaths which encourage walking and cycling by minimising distances between frequented facilities served by an efficient low-emission public transport network with stations planned to facilitate minimum walking distances, and measures to reduce traffic speeds (traffic calming) outside of established transport corridors provided with an infrastructure of ample cycle parks, sheltered bus stops and the minimum necessary car parking spaces

Alternative fuels for vehicles:

DME RME Biogas Ethanol Electricity

DiMethyl Ester RapsMethyl Ester

Energy used in transportation. [14]

Strategies to reduce private car use will be most beneficial and successful in mixed-use developments where alternative modes of transport can be offered i.e. an efficiently run public transport network. Design Pedestrian routes should be safe, attractive, and easy to use. The following issues should be considered: seasonal solar shading or access depending on the climate shelter from wind, driving rain and snow landscaping materials energy-efficient street lighting of minimum wattage and with shielded fixtures 3.6.2 Renewable vehicle fuels Renewable vehicle fuels have a range of benefits, including lower emissions, and unlimited supply when compared with conventional fossil fuels. Biodiesel fuels such as RME, a product of rapeseed oil, offer the benefits of a renewable energy source whose pollutant emissions may be eliminated using vehicles equipped with catalytic converters.

Internal street network favours pedestrians and cyclists, Kronsberg.

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3.6.3 Information systems and telematics Technology has its part to play in improving urban transport networks, and many examples of its use in increasing the efficiency of public transport can be found across Europe. Advanced Transport Telematics (ATT), the transmission of computerised information over long distances, is used for giving priority to buses at traffic lights, or data to passengers, for example. Road management systems which improve the efficiency of public transport and reduce private car use include co-ordinated fares, and road charges based on car use. Microprocessor chips and smart cards can be used to track municipally-owned bicycles and low-energy vehicles available for hire. 3.6.4 Case Study Copenhagen Free Bike Scheme Greater Copenhagen has 1. 7 million inhabitants, with 480,000 people living in the municipality of Copenhagen. Approximately one third of commuters in Copenhagen travel to work by bicycle, a third by public transport and a third by private car. The City of Copenhagen has an extensive network of bicycle tracks throughout the city. To encourage the use of bicycles in the city, the Free-of-Charge City Bikes Project was launched in 1994, and today there are 2,500 free City Bikes in the streets. City-Bikes are available from numerous City-Bike racks throughout the city, for a nominal deposit. The bikes are available from April to December. In December they are collected, repaired and stored during the winter. The City-Bikes can only be used in the city centre, as specified on maps provided at each City-Bike rack. After use, the City-Bike can be locked at any City-Bike rack and the deposit is returned. The bike can be used for an unlimited time, but can only be locked at a City-Bike rack with the special lock provided. In this way, City-Bikes are kept in circulation continuously. 3.6.5 Case Study ZEUS in Bremen The THERMIE Integrated Quality Targeted Project ZEUS, (Zero and low Emission vehicles in Urban Society) involves a consortium of organisations active in the procurement of such vehicles in eight European cities. Cost and availability factors such as pricing, lack of fuelling and charging infrastructure, and lack of maintenance facilities, all contribute to limiting the use of zero and low emission vehicles. The aim of ZEUS is to demonstrate the role that European city and regional bodies can play in overcoming these market obstacles. The aim is also to generate wider interest in zero and low emission vehicles among large fleet operators, public transport and taxi services in participating cities, and allow such groups the benefits of lower prices by the procurement of these vehicles through ZEUS. The consortium is putting into service more than 1,200 low or zero emissions vehicles, of which more than 150 buses will use alternative fuels and PV generated electric vehicles. It is expected to save more than 4,600 tonnes oil equivalent annually, and to reduce CO2 emissions by 14,200 tonnes, CO emissions by 300 tonnes and NOx emissions by 115 tonnes. Car-share, Bremen, Germany As partner in the ZEUS project, Bremen has developed an efficient intermodal mobility service; a combination of public transport and an extensive car sharing system. This service offers a high level of flexibility and new options for reducing and adapting car use. Key technologies are modern telematics as well as the AUTOCARD car rental system. AUTOCARD members pay an annual fee of 30 Euros and are then only charged for actual costs based on the type of car used and kilometres driven. The prices for five different car categories vary from 1,2 Euro/h to 4,4 Euro/h. There are no extra costs for insurance and petrol. Special prices apply to cars hired for a full day or week. Users of small cars pay no charge between 11.00 pm and 7.00 am. The AUTOCARD incorporates an integrated computer chip, allowing it to be used as a personal car key. Users can collect a car at one of 28 public traffic nodes in Bremen. Cars may be booked at any time and when returning the car, a parking space is always available.

City bikes project, Copenhagen.

Zeus car sharing system, Bremen.

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4.

SELECTED DESIGN TOOLS

The complexity of urban design, which incorporates several levels of analysis from climatic to cultural, geographic to geometric, is fundamental to the difficulties encountered in the development of successful urban design tools. A wide range of design tools is available to aid in the design of more energy-efficient buildings. However, few tools have been developed to assess conditions in the urban environment at city block or neighbourhood scale, or to predict the impact of proposed buildings on an existing urban environment. Some design tools which address the environmental impact of a proposed development on surrounding areas are outlined below. ZEIS Sustainability Indicators are methods of analysis which attempt to quantify the many levels of environmental, social and economic impact of concern in urban design. The aim of urban sustainability indicators is to analyse an urban complex in terms of its environmental impacts. These impacts can be described broadly as inputs and outputs. Inputs refer to a citys resource consumption, outputs refer to its by-products, wastes or goods manufactured. ZEIS is a prototype for a computer aided urban design tool. Within six main categories (Energy, Emissions, Buildings, Transport, Services, and Environment), the programme has established approximately 100 criteria for sustainability. Developed by: LEcole dArchitecture de Toulouse, France.

Urban Pattern Renewable Energy Incineration Building Transport Industry Water Grey Water Public Lighting Waste Hydrology

Neighbourhood

Building Form

Building Quality

Indoor Comfort

Chemical Compon.

Solid Compon.

Sound Discomfort

Grey Water Recycling

BUILDING

EMISSIONS

Waste Public Lighting

ENERGY

URBAN SUSTAINABILITY

SERVICES

Water Lectures Education

ENVIRONMENT

TRANSPORT

Health Shopping Private Transport Pedestrian Roads

DOMAIN

Natural Zones

Natural Risks

Industrial Risks

Road Syst. Efficiency

Public Transport

Parking

CRITERIA

Canyon Canyon is a tool developed to calculate the dynamic evolution of ambient air in urban street configurations. The tool calculates the thermal balance in the street, taking into account short and long wave radiation, as well as other transfer phenomena associated with materials and components in the street. Developed by: Group Building Environmental Physics, University of Athens, Greece CPCALC CPCALC is a tool developed to calculate the air pressure distribution around buildings. The programme is designed for a large number of building configurations. Developed by: Polytecnico di Torino, Italy Townscope Townscope II assesses thermal comfort, critical wind discomfort risk and perceptive qualities of urban open space, and provides an integrated multi-criteria decision module to rank various alternative proposals. Developed by: University of Lige, Belgium

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5.

REFERENCES AND BIBLIOGRAPHYConference Papers

[1] United Nations World Commission on Environment and Development, Our Common Future, (The Bruntland Report), 1987 [6] Alcock R, King C, Lewis J O, Solar Thermal Systems in Europe, EC DG XVII, ESIF, 1998 [9] Hough M, Cities and Natural Process, Routledge, 1995 [10] Mascaro L, Urban Environment / Ambiencia Urbana, Sagra-Luzzatto, 1996 [11] OCofaigh E, Fitzgerald E, Lewis J O, A Green Vitruvius - Principles and Practice of Sustainable Architectural Design, James and James, 1999 [12] Sevilla A, Landabaso A, Present Tools to Shape Sustainable Cities, Geohabitat, 1998 [13] Barton H, Sustainable Settlements - a Guide for Planners, Designers and Developers, Bristol; Luton; University of the West of England; Local Government Management Board,1995 [14] Vilanove R, The Balearic Islands shaping the 21st century, The Balearic Government, 1998 Benstem A, Wenau A, Hannover Kronsberg: Model of a Sustainable New Urban Community, Kronsberg Environmental Liaison Agency GmbH (KUKA) and the City of Hannover, revised version 1998 Daniels K, The Technology of Ecological Building, Birkhuser Verlag 1997 DETR, UK, Building a Sustainable Future - Homes for an Autonomous Community, Best Practice Programme, General Information Report 53, 1998 Givoni B, Climate Considerations in Building and Urban Design, Van Nostrand Reinhold, 1998 Gleiniger A, Paris - Contemporary Architecture, Prestel, 1997 Herzog T, Solar Energy in Architecture and Urban Planning, Prestel Verlag, 1996 Lloyd Jones D, Hudson J, Architecture and the Environment - Bioclimatic Building Design, Laurence King, 1998 Lopez de Asiain J, Arquitectura 5, Open Spaces of Expo 92, The Superior Technical School of Architecture of Seville (ETSAS), 1997 McNicholl A, Lewis J O, Green Design - Sustainable Building for Ireland, Stationary Office, 1996 OCofaigh E, Olley J, Lewis J O, The Climatic Dwelling, EC DG XII, James and James, 1996 Olgyay V, Design With Climate: A Bioclimatic Approach To Architectural Regionalism, Van Nostrand Reinhold, 1992 Passive Solar Design Studies Project Summary 045, Estate Layout For Passive Solar Housing Design, UK Dept. of Energy Contractors Report, Reprint Dec.1990 Rogers R, Gumuchdjian P, Cities For a Small Planet, Faber and Faber, 1997 Urban Technologies Sectoral Report 19951997, EC DG XVII Thermie publication, 1998 White R, Urban Environmental Management, John Wiley and Sons, 1996

Environmentally Friendly Cities Proceedings of PLEA 98 Lisbon, Portugal, James and James Science Publishers Ltd, 1998 [3] Viljoen A, Tardiveau A, Sustainable Cities and Landscape Patterns [5] Yannas S, Living with the City Urban Design and Environmental Sustainability [8] Gomez F, Dominguez E, Salvador P, The Green Zones in Bioclimatic Studies of the Mediterranean City Gonalves J, The Environmental Impact of Tall Buildings in Urban Centres Nikolopoulou M, Baker N, Steemers K, Therm