ctbuh technical paper - council on tall buildings and...

CTBUH Technical Paper

http://technicalpapers.ctbuh.org

Subject: Architecture/Design

Sustainability/Green/Energy

Paper Title: Tall Buildings Sustainability from the Bottom Up

Author(s): Guthrie, Alistair

Affi liation(s): 1Ove Arup Partners, London Offi ce

Publication Date: 2008

Original Publication: CTBUH 8th World Congress, Dubai. March 3 - 5, 2008.

Paper Type: 1. Book chapter/Part chapter

2. Journal paper

3. Conference proceeding 4. Unpublished conference paper

5. Magazine article

6. Unpublished

© Council on Tall Buildings and Urban Habitat/Author(s)

CTBUH 8th World Congress 2008 �

BiographyAlistair Guthrie is a Director of Ove Arup & Partners. Alistair leads the Sustainable Buildings Network for ARUP in Eu-rope and is a Founder Member of the UK Green Building Council.

He has a wide experience of working in multidisciplinary teams on the design and supervision of services in building projects in England, Italy, Holland, France, America, Japan, China, Australasia and the Middle East. This experience in-cludes not only detailed design work in Mechanical Services, but also Building Physics, Energy Studies, Climate Change Analysis, Daylighting, Air Movement Analysis and Microclimate Design. He believes strongly that a holistic view of the built environment is the only way to a sustainable future.

Alistair has provided Building Services and Sustainable Design advice for a wide variety of building types including high rise projects in China, The Emirates, UK and the USA. He is a Special Professor of Environmental Design University of Nottingham and a founder member of the UK Green Building Council.

[email protected]

Tall Buildings Sustainability from the bottom up.

Alistair Guthrie, BEng, MSc, CEng

Director Ove Arup Partners, London Office, 13 Fitzroy Street, London W1T 4BQ, UK, Email: [email protected]

Abstract This paper examines the idea that a building can only be sustainable if it is so in the context of the community which uses it. It concludes that tall buildings can contribute to the sustainability of the community. It considers SPeAR as a way of measuring sustainability and provides an example of such measurement.

Keywords: Tall Buildings, Sustainability, SPeAR.

Introduction A building can only be classed as sustainable if it is

so in the context of the total impact that it has on the society in which it is placed. Indeed it is not possible to argue that a building in and of itself is or is not sustainable it is about how it is used and the impacts that it generates. These impacts will span the life of the building from its construction, operation and eventual dismantling. As we consider this it is useful to remind ourselves of the Bruntland definition of sustainable development “meeting the needs of the present while not compromising the ability of the future to meet its own needs”1

In this context is a tower more or less sustainable than other buildings? Are there elements of high rise construction that are intrinsically bad for the planet? What makes a tall building sustainable? What we can be sure of is that there is not a generic answer to these questions. All our answers will begin “it depends on”. What are the fundamental considerations?

Location By this I mean not only where in the world the

building is located but in what type of city and where in the city. This is mostly about transport. Public transport has much lower impacts on society than private transport. It is per person less polluting, more energy efficient, more socially cohesive and cheaper. A building and its operation that increases the use of private transport due to its location is less sustainable than a building that is close to public transport nodes and encourages its occupants to use them. Tall buildings provide the potential to increaseaccommodation for living and working around publictransport nodes. A rough survey of workers traveling to an out of town office park with no good public transport concluded that the workers used nearly 10 times more energy in traveling to work than the building and their operations within it used during the day. There are many examples of clusters of tall buildings in city centre locations with excellent transport links e.g. Manhattan, Chicago, London. Cities that have copied tall buildings

without consideration for the large people movements they generate have major parking problems, pollution and congestion which downgrade the quality of the city life and increase overall carbon output (Fig. 1.)

Figure 1. Relationship between urban form and transport energy.

Newman, P and Kentworthy, J, Cities and Automobile Dependence. An

International Sourcebook. 1989.

ConcentrationFollowing on from the idea of city density around

transport nodes is the idea of concentration of activity. The greater the density of the city the more connectivity is generated with its benefits for social interaction, reduction of intracity transport and its associated issues of energy use, and the potential for a better work life balance. It is evident that tall buildings can play a major part in increasing this concentration. The potential for vertical cities where the functions of a city are not divided into different buildings but occur as a mix of uses within a single tower was first envisaged by Corbusier in 1947 when he built his unite`d` habitation in Marseilles taken up by Frank Lloyd Wright in his 1956 one-mile-high skyscraper project for Chicago.2 With a few exceptions our cities have not been built in this way. This is because a multifunction tower often has less efficient floor plates due to the desire to segregate different uses with different elevators and/or different building services systems. This makes the tower less attractive in the short term to developers and funders.


Tall Buildings Sustainability from the bottom up.

Alistair Guthrie, BEng, MSc, CEng

Director Ove Arup Partners, London Office, 13 Fitzroy Street, London W1T 4BQ, UK, Email: [email protected]

Abstract This paper examines the idea that a building can only be sustainable if it is so in the context of the community which uses it. It concludes that tall buildings can contribute to the sustainability of the community. It considers SPeAR as a way of measuring sustainability and provides an example of such measurement.

Keywords: Tall Buildings, Sustainability, SPeAR.

Introduction A building can only be classed as sustainable if it is

so in the context of the total impact that it has on the society in which it is placed. Indeed it is not possible to argue that a building in and of itself is or is not sustainable it is about how it is used and the impacts that it generates. These impacts will span the life of the building from its construction, operation and eventual dismantling. As we consider this it is useful to remind ourselves of the Bruntland definition of sustainable development “meeting the needs of the present while not compromising the ability of the future to meet its own needs”1

In this context is a tower more or less sustainable than other buildings? Are there elements of high rise construction that are intrinsically bad for the planet? What makes a tall building sustainable? What we can be sure of is that there is not a generic answer to these questions. All our answers will begin “it depends on”. What are the fundamental considerations?

Location By this I mean not only where in the world the

building is located but in what type of city and where in the city. This is mostly about transport. Public transport has much lower impacts on society than private transport. It is per person less polluting, more energy efficient, more socially cohesive and cheaper. A building and its operation that increases the use of private transport due to its location is less sustainable than a building that is close to public transport nodes and encourages its occupants to use them. Tall buildings provide the potential to increaseaccommodation for living and working around publictransport nodes. A rough survey of workers traveling to an out of town office park with no good public transport concluded that the workers used nearly 10 times more energy in traveling to work than the building and their operations within it used during the day. There are many examples of clusters of tall buildings in city centre locations with excellent transport links e.g. Manhattan, Chicago, London. Cities that have copied tall buildings

without consideration for the large people movements they generate have major parking problems, pollution and congestion which downgrade the quality of the city life and increase overall carbon output (Fig. 1.)

Figure 1. Relationship between urban form and transport energy.

Newman, P and Kentworthy, J, Cities and Automobile Dependence. An

International Sourcebook. 1989.

ConcentrationFollowing on from the idea of city density around

transport nodes is the idea of concentration of activity. The greater the density of the city the more connectivity is generated with its benefits for social interaction, reduction of intracity transport and its associated issues of energy use, and the potential for a better work life balance. It is evident that tall buildings can play a major part in increasing this concentration. The potential for vertical cities where the functions of a city are not divided into different buildings but occur as a mix of uses within a single tower was first envisaged by Corbusier in 1947 when he built his unite`d` habitation in Marseilles taken up by Frank Lloyd Wright in his 1956 one-mile-high skyscraper project for Chicago.2 With a few exceptions our cities have not been built in this way. This is because a multifunction tower often has less efficient floor plates due to the desire to segregate different uses with different elevators and/or different building services systems. This makes the tower less attractive in the short term to developers and funders.


Concentration and mixed use also has the potential to improve our energy production and distribution systems. In many of our cities we generate electricity from fossil fuel in one part of the city throwing away the heat the process produces whilst in other buildings or areas of the city we use fossil fuel to generate heat either for space heating in cold weather climates or for heating domestic hot water. Sharing the heat and power across the city particularly between the commercial and residential sector has the potential to reduce our overall energy use, green house gas emission and cost and yet in some of the most developed economies in the world such as London there is almost no use of city wide combined heat and power schemes. In the absence of city wide schemes mixed use buildings and particularly large high rise buildings can share heat and power between their user functions and reduce the overall emission of green house gases.

Concentration particularly into high rise also gives opportunities to release land to both community use and to ecological benefit. Potentially it could prevent our cities sprawling into the countryside or allow the reestablishment of open spaces for leisure, recreation and the recolonisation of flora and fauna. A future more sustainable community may well have living and working functions clustered into relatively dense high rise conurbations surrounded by green parks, wild spaces, efficient low energy food production and areas to harness wind and solar energy either directly or through short rotation energy crops. Many of our towers are an icon of separation rather then a focal point in the community.

Figure 2. Electrical Load for a typical “Prestige” High-rise Office in

London. Pank, W. The Corporation of London. Tall Buildings and

Sustainability. February 2002.

Light and Air Two of the most sort after commodities in our

working and living environment are light and air. Too little or two much is uncomfortable and cause for complaint. In high density low rise accommodation they are often in short supply. Buildings are deep, they

overshadow each other, the air around them is often polluted and overheated in summer. They rely heavily on the use of artificial light and mechanically transported and conditioned air (Fig. 2.). The high rise provides the opportunity to rise above this and connect into better light and air.

Controlled daylight through the façade is better liked by the occupants than electric light and can be provided without electricity cost for many of the working hours. Lighting is a major user of energy in a corporate office building. Providing daylight without adding to the air conditioning loads, free from excessive glare and with proper control is a very efficient way to reduce the energy consumption of a tall building in whatever climate region it is located.

Figure 3. Sketch of an urban heat island profile

http://www.epa.gov/heatisland/about/heathenv.html

Our tall buildings can either be isolated from the air that surrounds them or connected to it. The air can be too polluted, too windy, full of dust or sand, too hot or too cold. Cities often create their own microclimates with temperature in excess of the surrounding area (Fig.3.). It can on the other hand provide fresh air, welcome air movement and free energy for cooling. In most climates both scenarios are true at different times during the year. A sustainable building needs to reduce the energy required to provide ventilation and climate control to the building by harnessing the free energy available from the surrounding air in a controlled and seasonal dependant manner. In some places the most efficient way to do this will be through controlled openings in the façade for example the commerze bank building in Frankfurt or the GSW tower in Berlin (Fig.4.).

This works because much of the year the outside air is cooler than inside and is relatively clean and dust free. In other places such as the Gulf the outside air is often dust laden and above the temperature and humidity required inside for much of the year. This needs a solution which provides cleans and conditions the air before introducing it into the building. This needs to be done with the minimum of energy.

Renewable energy The ultimate goal of any tall building could be to

generate in the course of a year as much energy as it uses.


Figure 4. GSW Building Berlin and Commerzebank Frankfurt. Arup I

Base

This is often defined as a carbon neutral building. We have seen that if our building is truly connected into a sustainable community then it is the community as a whole that needs to achieve this goal. However the more that individual buildings can do to drive down their energy consumption and make a contribution to the overall energy generation then the more likely the community goals will be met. Tall buildings in general use more energy per m then low rise buildings (Fig.5.)

Figure 5. Breakdown of Electricity End-Users In Selected Offices in

Hong Kong., Joseph, C. Lam, Ricky, Y.C Chan, C.L Tsang, Danny H. W.

Li, Energy Conservation and Management, 45 (2004) 829-844.

Much of this increase is in fans, pumps, and air conditioning loads. The opportunity for tall buildings is the high ratio of façade surface to plot area. In some climates and locations it is possible to generate between 10 and 15% of the electrical requirements of a tall building from photo voltaic collectors located on the facades. The shape, orientation and issues of overshadowing will greatly influence this figure. The greater the concentration of high rise buildings the lessthe opportunity. Clearly the more efficient the building is

in operational energy use the greater the proportion of the electricity can be derived from this source.

In hot sunny areas of the world power generation from tall solar chimneys or solar arrays as part of a community strategy should be developed.

Much has been made of the potential of wind derived energy in the context of tall buildings. The energy available is proportional to the area over which it can be harvested. The top of a tall building has a relatively small area in relation to the size of the building. Some designs have enhanced this by using the towers themselves as wind catchers concentrating the wind from a larger area onto a turbine or series of turbines. It is unlikely that even with these strategies that the wind will provide much more than 5% of the electrical requirements for the building. Again it will be more efficient and cost effective to reduce the overall energy consumption of the building and provide wind energy as part of an overall community strategy.

Figure 6. Raw materials consumption in the United States. Phillippe

Rekacewicz UNEP/GRID-Arendal, 2004

Materials Construction uses a very large percentage of raw

materials (Fig.6.) A high rise building will almost certainly use more materials in construction than an equivalent usable area low rise building. Depending on its location a tall building will use around 150kg/m² of steel whilst a low rise building might use 75kg/m². We are concerned about this because more material means more energy used in production and transportation, it potentially means more waste and also more of our limited natural resources being used up. To offset this we need to enable the building to be usable for a long time by designing it so that it can adapt to future needs of the community, we need to make sure that the materials we do use can be reused and eventually recycled and with minimum additional energy. Locally sourced materials,


aggregates from waste processes and off or on site prefabrication can all contribute to reduction in use of new materials as well as reducing cost and energy use. The type of material can have a significant effect on other issues such as energy consumption; see for example a study of a light weight building vs. a concrete building in the Gulf (Fig 7 & 8). The heavy weight building has a peak load 40% less then the light weight building.

Figure 7. Solar Gains for Static, Lightweight Building, orientated

E-W with Windows N&S. In the Middle East, Arup Unpublished.

Figure 8. Solar Gains for Static, Heavyweight Building. In the Middle

East, Arup Unpublished.

Water In some locations the availability of clean fresh

water is a key driver to the long term sustainability of our communities. What impact does this have on tall buildings? Possibly the major contribution can be to the reduction in use of water by the collection and recycling of grey water and its use for flushing toilets and irrigation. The opportunity to do this is greater in buildings used for living rather than working and mixed use high rise towers provide a good opportunity for this. The design of recycling systems needs to ensure that the energy used in pumping and treating water does not negate the water saving in the overall sustainability equation.

The idea of concentration of the built environment into a small foot print by going tall potentially increases the area of land to absorb excessive rainfall and reduce runoff. This is potentially important in areas where climate change predictions are forecasting increasingly severe storms

Measurements of Sustainability Measuring the total impact of a building is

essential if we are to consider its true impact on the sustainability of the community now and in the future.

Figure 9. Rendering of London Bridge Tower Renzo Piano Building

Workshop

By way of an example we measured the impact of the planned new 300m London Bridge Tower (Fig 9.). We tried to asses not only the performance of the tower itself but the impact of its development on the surrounding community. We have considered in some way all the issues discussed above. To do this we have used a tool called SPeAR that was developed by Arup to asses the sustainability of projects, organizations, developments or buildings using four pillars of sustainable development. Environment, Natural Resources, Social and Economic. It calculates the relative impacts of a number of factors under each of these headings and represents them on a chart to enable visualization of where improvements can be made or to enable comparison of different options or projects. The representation of the circle indicates that many of the impacts are interdependent and that achieving good scores in a few areas does not necessarily make for overall sustainability. This particularly relevant when we think of tall buildings where we have seen that the driving issues in creating sustainable tall buildings may not be the building itself but its impact on the community.

For a SPeAR Assessment of London Bridge Tower see Fig 10. London Bridge Towers scores very well under Transport, Environment and Economic impacts. There is little car parking, good provision for cycles, and it is built right adjacent to London Bridge station which providesdirect train access to the South East of England a popular commuter area. The station is also is a major hub for the London underground system and a bus terminal for routes across London.


Figure 10. SPeAR assessment of London Bridge Tower, Arup

The development of London Bridge tower has resulted in Improvements to the station concourse and the bus terminus which will give, improved air quality in the area and generally better public facilities and open space. The London Bridge Tower is mixed use. It has commercial offices, an hotel, residential apartments and public access to viewing galleries and restaurants at several levels (Fig 11.). This allows the sharing of energy, particularly heat, reducing overall consumption. It provides a wide range of employment types, increased choice of products/services and increased job opportunities both during and post construction. It engages with a wide variety of stakeholders improving the vitality of the area and potentially providing regeneration to the whole London Bridge area. It replaces an office only building with a similar ground footprint with a mixed use building of much greater floor area increasing employment in both diversity and quantity.

The building has been designed to be energy efficient. 3 It uses the opportunity of mixed use by providing a combined heat and power installation, generating power for the office accommodation and using the heat for the hotel and residential. In summer excess heat can be used to provide cooling through an absorption chiller. Waste heat can be rejected naturally by wind blowing across a “radiator” of finned tubes on the top of the building. The performance of the façade, a triple skinned externally ventilated solution has been designed to provide excellent performance in both summer and winter, combining shading and natural heat rejection, whilst maximizing the daylight into the floor plate. At many corners of the tower there is a naturally ventilated winter garden which enables the occupants to engage with the outside and can be used as a breakout space or for meetings.


Offices

Public Space

Plant

Let to TfL

Plant

Public Space

Shangri-La Hotel

Plant

Spa

Residences

Plant

Public Space

Radiator

306m

Figure 11. Mixed use at London Bridge Tower. Renzo Piano Building

Workshop.

As can be seen from the SPeAR diagram some areas could be improved from a sustainability point of view.

There is no recycling of the water and although this was considered, the easy availability and low cost of water in this area meant that recycling could not be justified.

Although the tower is mixed use and provides employment across a wide range of social groups the accommodation and hotel is aimed at the very top of the social scale for economic reasons.

There is a plan to recycle on site most of the demolition material from the existing building but the construction materials would benefit from a more targeted policy on sustainable materials, embodied energy and sourcing.

Conclusion Tall Buildings can play an important part in the

sustainability of the community. The negative issues of increased energy use and more material can be offset by improving efficiency and considering the benefits that location and concentration might have for the community.

References THE BRUNDTLAND REPORT (1987) Our Common Future, Oxford University Press ABEL, C (2003) Sky high. Academy Publications London SUMNERS J., The shard at London Bridge – Bridging the gap between M&E and structure unpublished paper.

ctbuh technical paper - council on tall buildings and...

Documents