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sustainable placemaking forum 79 Parkway London NW1 7PP tel. 020 7485 8555 fax 020 7485 1232 |
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seminar proceedings |
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A seminar series organised by HTA Architects Ltd Report of seminar on High
places: the design of green skyscrapers Main conclusions
High places: the design of green skyscrapers Main speaker at the seminar was Ken Yeang, a partner in the Malaysian firm T R Hamzah & Yeang, well known for his work on bio-climatic skyscrapers. Yeang and HTA Architects Ltd are collaborating on the designs for London's first eco-tower at Elephant & Castle. Ken Yeang has been involved in the design of skyscrapers for the past 25 years. But why skyscrapers? And why green? Skyscrapers occur largely because of urban growth and rural migration. When that happens a city can only go sideways, eating into arable or other vegetative land. The way to save that arable land is to intensify cities by going upwards. He pointed out that, as Corbusier argued, skyscrapers have a smaller footprint and can provide more open space. The United Nations uses the argument that it lowers transportation costs and thus energy consumption. There are many definitions of green design. There are contradictions between existing technology and nature. The first starts with predetermined objectives whereas nature has a discernment of what is there rather than starting with fixed goals. Existing technology looks to process efficiency and mechanistic approaches while nature looks at systemic harmony and an organic, holistic approach. The aim is to try to bring this together. Architecture is like a prosthetic device - it is artificial, and man made. The present built environment is mostly inorganic. What is needed is to start with the ecological system and using organic with inorganic components to achieve a balanced ecosystem. Ken Yeang started to look at different ways of achieving this. One way is horizontal greening either through putting all the greenery in one place similar to traditional city squares. The alternative is vertical greening allowing migration of species through it. He went on to explain some of the issues and techniques that have to be followed. For instance, planting has to follow the solar path and requires hardy species - as is being considered for the Elephant and Castle scheme. It is important to understand the system of energy and environment. There are four basic categories to be considered: passive mode which avoids any electro-mechanical devices; mixed mode using some electro-mechanical devices; full mode perhaps using environmental controls; and finally productive mode, which involves the building being used to generate its own energy through photo-voltaics and other systems. With ecological design the strategy has to optimise all the passive options, before progressing to the mixed and other options. Most architects do it the other way round - they move straight to the 'full' mode and see what systems they can add to it to achieve low energy - as a result they miss a lot of opportunities. In Elephant and Castle, the aim is to use composite strategies. There are low temperatures in winter so the proposed approach is to use solar gain and other passive features. Most ecological designers define eco design as designing with minimal impact on the environment but it is a battle that you can never win. But there are ways to include biodiversity. One approach is the 'landscaped bridge' which immediately improves the environment, encouraging species to move in from nearby green areas. It involves working in a different way - it means putting the buildings in a park rather than building first and creating the park after. Designing high rise as a city in the sky High rise buildings are so dense that you cannot look at them as conventional buildings but must see it as designing a city in the sky. Most high rise buildings are nothing more than a series of trays stacked on one another. This creates instant compartmentation. Instead there is a need to create organic spaces and linkages. The biggest challenge is to design in a humane and organic way. It is possible to create large parks and squares to achieve multiple circulation and recreate ground conditions in the sky. It is important to understand that ecological design requires an understanding of a site's carrying capacity. It involves 'sieve' mapping devices to achieve minimum impact on the existing natural environment. It requires analysing the current species and vegetation and deciding what to bring in. An example is the Nagoya Tower in Japan, 1997 built to house Expo. The authorities were planning to build on 150 hectares of land that contained rare species. Further damage would be caused by 250,000 people trampling over the site for six months. Instead, a 'vertical' expo was proposed with a reduced built footprint, and incorporating a multiple vertical circulation concept, and horizontal and vertical zoning. But as well as simply introducing nature, schemes must involve the systematic greening of the man-made environment. Recycling and using natural resources Ecological design is a knowledge-based approach - analyse the information, evaluate it and change the design. One of the issues is recycling which must be used at every stage of construction- it should take into account replacement rates - and incorporate lifetime energy costing. It must include water recycling, perhaps using collectors and filters to make the rainwater potable. Another aspect is to use wind conditions. This can involve such things as using wing walls as a device for bringing in air for cooling or natural ventilation. It requires the use of computer fluid dynamics in design calculations. This all needs detailed investigation of wind, temperatures and so on for each façade. Thus ecological design is very complex. It involves the use of partition matrix approaches to indicate how one factor impacts on another and the effect of architecture on the environment. It shows that you cannot change one thing without changing the others. There is still a need to develop ecological design criteria and global monitoring. Basically ecological design is in its infancy. Ecological designers are still experimenting with a range of systems and there is a long way to go. Discussion I am interested in eco towers. To what extent is there a conflict between the way you orientate a building to maximise green benefits, and commercial imperatives? For instance, in Elephant and Castle, I imagine you want the building facing north to get views over the City to increase the value of flats, but green imperatives might push you in a different direction. Housing association
Green design has no hard and fast rules. There is a middle way between these and you can achieve them by using, for instance, double glazing and low e glass. Ken Yeang
Want plants can you use 40 floors up? How long before they need to be replaced? What is the maintenance regime because they will need more care, I imagine, than in a park. Consultant
It is hardy species - like those you see along railway lines and beside roads, because these survive in hard and local conditions. They are not just decorative. Like any garden they involve upkeep - maintenance is required. On the outside, maintenance is sometimes carried out using the cleaning gondolas. There are a whole series of issues to be tackled: who carries out the servicing, drainage, protection against freezing, avoiding roots penetrating the structure - hardy plants have roots that tend to dig in. But perhaps the biggest problem is to get daylight at the back of planters. This involves rotating them to get even light. Ken Yeang
The Ocean Estate, where I am working, is in very poor condition. It needs to be rebuilt and we would like to have an eco tower. However, a problem comes up with communication with the occupants. They would all really like to have houses with gardens. Have you had any experience of talking with people who start from a very low knowledge base? Consultant
We have had problems convincing people that they have to be more attentive to the building. They have to treat it as a machine and adjust throughout the year. Ken Yeang
We are working as master planners on the Ocean Estate. It strikes me that the reason why people say they want a traditional house is usually to do with a set of presumptions and prejudices about what a house on the ground has to offer them. Our experience of consultation and enabling people to make choices that are outside their normal range of perceptions about what is possible, is to break down the issues that concern them, to find out what their aspirations and needs are. Then we factor out those issues and offer them a range of options and ask them to test that range of options against their priorities. There is a huge range of issues. People find that a house and garden might produce some characteristics that they cherish. But I recall a resident of a tower block in Bristol, which was demolished and replaced with terraces. When asked what difference it made, he said it was pretty much the same - the noise had moved from above and below, to the sides. We have to get to the bottom of issues such as noise, cost and access to services and shopping. Ben Derbyshire
I have to say that social housing tenants have a deep mistrust of housing management. They have doubts about commitment, particularly to long term costs. Are the long term costs of eco-towers much higher? If so, I have personal doubts about their sustainability for the public sector. Local authority
There are benefits in high rise such as security. We also have greater shared facilities. Thirdly, internal maintenance is less. By designing high rise with communal spaces, you are actually providing the opportunity to interact and socialise. At Elephant and Castle we aim to try and produce a suburban house in the sky. We should try and redesign and think of the future. If we build low rise we run out of land and you have all the other problems of maintenance, security and infrastructure which are much more expensive than high rise. With high rise, elevators are a much more efficient way of moving about. There are a whole series of pluses and minuses, of pay-offs and what you prefer. Ken Yeang
The history of urban regeneration has been to replace what were highly imaginative, high density schemes but poorly maintained. People were asked whether they would rather have what they had, or houses on the ground. What has happened is that we have ended up with a series of extremely poor quality monoculture single tenure estates. The essence is choice. If we give them proper choice the outcome will be sustainable because people will look after them. For places like Ocean Estate and Elephant and Castle, the issue is to provide densification, to offer a range of tenures and allowing choice in such a way that those who wish to exercise it do, and also can afford it. There isn't much merit in building something at great expense and letting it at £75 a week - that is what Camden is doing already. If Camden operated a bit more like the Duke of Westminster and exploited its real estate, they would get much more revenue and a better balance of people and uses. Ben Derbyshire
How does the relationship of other buildings affect the performance of an eco-tower? If in future someone decides to build another high rise nearby, how would that affect its performance? Housebuilder/developer
Rules have to be established - for instance, shadows can seriously affect public parks and other buildings. Cities such as Beijing have rules about it. Wind can change enormously. That is where urban design comes in, to make sure there are envelopes and to avoid tower block owners leaping down each other's throats. In Japan, they have carried out research into the consequences of living in high rise. The conclusion is that it does not make people crazy, but it does affect relationships between parents and children. In a traditional home, parents can watch the children from the kitchen. With high rise, once they have gone downstairs, that relationship has gone. That backs the case for building communal spaces in the sky and not just on the ground floor. Ken Yeang
The ability of any high rise to reflect eco concerns has to be paid for by the commercial content of the scheme, whether it is residential or office. Developers obviously try and maximise floorspace. Surely this is a key ratio. Are you hoping that extra floorspace will be allowed, or that there will be an element of added value because of your design? I wondered what your view was and your experience. Consultant
Why do you do it? It is a nice thing to put in vegetation. Vegetation creates a much healthier micro climate. For office buildings, for instance, one of the biggest rationales for natural ventilation is that it improves productivity. In sealed environments you end up with such things as itchy eyes and other problems. Good architecture is about how you spend the money rather than how much money you spend. It is up to the architect to design to budget. But ecological elements don't necessarily cost more - they may cost less and may make the building more efficient. Ken Yeang
We have built to 10 storeys and looked at the use of open space at a higher level - it adds costs but also desirability. It is an argument for adding floors. The problem we have is that not every local authority likes the idea of public space at a higher level, and thus this can create problems at the planning level. Housebuilder
I think we are beginning to realise that heights have to rise, but it requires a lot of extra management. Too often, management is taken away - this happened with Trellick Tower which was originally designed to have a concierge system. Local authority
Management is also an issue for the private sector. There are many schemes which have been built where the management structure was developed too late, causing issues about who pays for the service charges, what counts as the public realm, and so on. It seems all these issues are compounded in high rise schemes. I am interested to know what work has been done on sustainable management structures: who is paying for what, and what will it cost; what can the public sector afford and pay for? Property manager
The community land trust model starts from the presumption that land and its value are important. High cost land can create the situation where people can afford the construction cost but not the management. The Ocean Estate is just ten minutes by public transport from Canary Wharf and Bank station in the City of London. It took a local authority genius to create flats which became unlettable. The position is that eco towers are a way of creating value in an area but it needs to meet the aspirations of people. High rise developments have been wrecked by constraints on local authority management which were, in the main, imposed on them [by central government]. As a result they reduced the services not out of conviction but out of necessity. That has created the disillusion with the idea that things can be managed. I think we have a very uphill battle to persuade people that their quality of life will be greatly enhanced by a much more radical approach. Consultant
On the point of incorporating public sector housing within the new forms and the ability to manage them, the possibility is there to use the increase in urban density to make more space where it doesn't exist, and rethink how urban uses might be combined in a more effective way. And to dissipate the problems caused by large scale monocultural public sector developments which appear to have become deeply unsustainable, not just in physical terms but also socially, economically and politically. I believe the ecological issue is a sideshow compared to the conditions to which we subject large proportions of our urban population. These buildings hold out the promise of the ability to reinvent the urban situation. Consultant
There are a lot of different qualities that interact such as lighting, heating, rainwater, wind and so on. Is there a scale of values that you use to determine which has priority in designing an eco tower, or do you model intuitively? Architect
This often rests with the client. At the end of the day, the lower the income, it generally means the lower the budget. Ken Yeang
I come from a sector mainly looking at non-domestic buildings. What can 'kill' buildings is unmanageable complexity. One of the big problems is that often in the initial years conditions deteriorate, and the quality usually spirals down. What we need is to learn how to make things spiral up. It is such a shame, because of the potential of eco towers. Is the Far East better at it? Consultant
In my view people are the same all over the world. Ken Yeang This seminar series operates on a 'Chatham House rules' basis. However, many of the participants have already expressed their willingness to have their contributions credited to them. In the other cases, speakers have not yet given clearance - no inference should be drawn from this. Anyone wishing to quote the speakers should speak to them direct for their permission. For further information, contact Chris Bazlinton, Editor on 01279 771468. HTA Architects Limited 79 Parkway London NW1 7PP telephone 020 7485 8555 fax 020 7485 1232 email hta@hta-arch.co.uk ISDN 0207267 0061
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