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The Eden Project couldn’t have been done without the guys in this room (Andrew Whalley Nicholas Grimshaw) spending at least £5m of their own collective labour to prove that it was possible, it was a huge act of faith and for us it was terrific. – Tim Smit

What we ended up with was probably one of the world’s largest meccano sets ever created. All these crates arrived, all beautifully labelled, with all the connectors in it, all the pipe work, all the nuts, bolts etc and then we had the fun of actually assembling it. – Andrew Whalley

 

Context

The biggest obstacle in regards to the site location was the roads. There is a dual carriage way but the roads access were not good. That was why one of the reasons when we developed the structure that was literally like a meccano set in crates was made the way it was so that it could be transported by much smaller vehicles we only had a few sectional trusses that joined the whole thing together. The other issue is that the beauty of the site that  for a  hundred of years people have been digging a big hole in the ground creating this beautiful typography, But meant that in a year or so we had to stabilise it and make it sound. China clay is removed by high pressure water. It is made of very soft graymail material. what it means is when it rains its gets soft and moves and shift. and intend where we proposed the visitors centre to be over the course of a night it disappeared because we didn’t finish the stabilisation. so that was quite a challenge. we actually ended up doing the ground work in the wettest winter ever recorded. so not only was it difficult in the first place but the climate that year did not help. a lot of water that we need to pump. the water table was the other issue there. so they were the 3 main issues of the site.

the plants take priority in everything. We had something called the green team. Tim smit ,through his work at the lost gardens of heligan, Made connections with the royal horticultural society and expert there. they did a lot of research into plants. He already had a expert team that became the green team that advised us on the technical criteria we had to. The main issue that they were concerned with was light specially the levels of light. We live in the northern hemisphere the light levels in winter is reduced to a few hours. so we were searching for a structure that had minimum structural members to maximise the structure openings for light. one of the reasons why we choose to go with etfe foil is that it has a high level of transparency. That was the first criteria. The second criteria was probably thermal requirement. which is quite broad. the humid tropics of the rainforest biome which is a the most sensitive. The plants don’t like the temperature to fall to a certain point but saying that they can it’s just they go into hibernation. in their equator climate they grow all year round. What happens in Eden is that they become more dormant in the winter months.

With Arup we did a lot of CFD analysis which is out lined in the Blueprint article. we deliberately used the typography of the site as the architecture which gave us drama. So that plants that weren’t mature we still had a sense of height. we also wanted to use it as part of the environmental system. The team was for the environmental was Arup and Anthony hunt was the structural. our environmental system was done by Alistair Guthrie who just finished Renzo Pianos kansai airport. There they managed to use the shape of the roof to circulate the air as opposed to ducts which is the design that we wanted to implement into Eden. this was the early days of the cfd analysis. We still managed to see how air moved i was quite keen on not have things on the roof. was the CFD showed that during the summer and large heat gain that you have to have a major opening at the creasant at the top. That is why we have a flower opening form on the top to create air movement though. the other thing we found over the past years is that the energy consumption is less that we found. We found that the solar gain, the thermal mass and thermal store was so much that we needed less energy than we thought. It’s all about the plants. People have the make do with what is there. there is concessions like there is cooled rooms for old people where they can go in to go in, but the whole project is geared to the plants. High humid, temperature and light which is critical etc. agitation of the plants. there is a lot of air movement especially in the summer. the plants need to be exercised. If they don’t they grow to quickly and tangley [sik]. There has been a lot of trimming on the plants. The Mediterranean biome the light is more important as the tropics has more under story plants. Gardens by the bay, one could say they ripped us off, at least Patrick admits it. They had a lot of solar shading, but it turned out that the plants died because of this so they just turned up the air conditioning. the truth of it is that the amount of the solar shading blocked to much light and killed the olive trees. Right at the beginning our green team said that you cannot have any mechanical solar shades as it cuts out too much light, so we had to have an environmental system that would allow so many air changes so that it the thermal comfort would be for the people as well as the plants.

because we wanted a transparent structure I believe we still obtain record for the largest single pillow size of 11m in diameter. the thing about etfe foil is that you can’t just make it thicker to make it stronger, it becomes more brittle . so we did a lot of wind tunnel analysis. The main structural challenge is uplift not down lift. the wind blow across the top of the pit it’s trying to suck the pillows out of the structural frame system.  so there is a tension force being applied to the pillows. so you have three layer pillows. The single outer layer is not strong enough to maintain this extreme condition. so we had a look at different options on how to make it stronger such as using cable system for additional strength. in the end we added double skin to the largest pillows. so these two skins work together to prevent the uplift.  we also designed for snow load which we didn’t think we would ever get in Cornwall and there where we have additional cables that sit underneath the frame. And of course after 5 years Cornwall had a massive snow storm.

Nero devised the structural system for the roof. the geometry there was very complex and marrying the dome and  the edge details were quite complex. There was a mathematical doctor from German whose solved the final detailing of the geometry. the more complex part if you ask Anthony hunt was the edge condition, the foundations were very complex. you have an undulating changing foundation around the edge all the biomes, a mixture of tense and compression with ground anchor. No one ever sees it because its underground. (awaiting photos, and drawings.)

Tim Smit were applying for one of the 12 grants. The idea was that each of region would get a millennium funded major project of cost up to £100 million. It was a complex equation, and one of the reasons why many of the projects failed was that the project has to be commercially viable in its own right. It needs to be a profitable business venture. It had to be self sustainable. There is not many public attractions apart from theme parks that are entirely self sustainable. They need subsidies  from the government. so that is why so many millennium project failed. Eden had to build a robust business case, that could work on predicted visitors number, ticketing sales etc. and i think that has always been the challenge for the project, having a scheme that buys it way with low ticket prices, due to its location Cornwall, and neighbouring attractions as opposed to that of the south east. If we take clients to the Eden project they are always amazed at how low the ticket price is.   we get money through things like the food and events that they do. with the music concerts and so on. They all help drive the revenue. We are now currently working on international Eden project. That would help the overall financial aspect of the project. so the fundraising meant we had to create a business model that worked and that meant scaled back the project from a £100 million project to £75 million. we had to work backwards from that figure and we found the cost of stabilising the ground cost a lot more than we anticipated. money disappeared before we even started the building. Then we had to redesign some of the buildings. For example the visitors centre which is the first thing that you enter. we had to change the structure, but in many ways I really like it. one time there was talk about having 3 biomes. As we got further into the project with the wasted money on civil engineering we realised that this was not viable and so had to scale back the biomes. so rather than scaling back both of the biomes, we scaled back the human tropics (rainforest) a little bit but not too much  and really scaled back the Mediterranean biome a lot. That is why the Mediterranean biome is so much smaller than the tropics. and the reason being , from Tim Smit, you needed something that lit the imagination, and having a huge rainforest biomes would do that, attracting people in and engaging them , and he was absolutely right. Having two medium size biomes wouldn’t do it, you need to have need a big anchor. there was a project running ahead of use in Doncaster called the earth centre and they original had a beautiful centre piece project designed Jan Kaplický future system called the ark. it was a beautiful butterfly and that’s what help them get their funding. They ended up cutting back and building smaller building instead and did not attract many visitors because of that. It needed to be entrepreneurial to attract more than a million people a year that you needed. we need to scale back , we cut down things like education building, we had to use porter cabins for a few years.

the air handling units on the outside of the biomes were down to economics really. the air handling units were distributed around the bottom of the biomes effectively blowing in warm air in the winter. the shape of the roof means that you can blow in warm air at the bottom perimeter and it will flow to the top without any ducts. The initial design was for the air handling units to be enclosed and quite elegantly designed enclosures. we knew they were going to be at the front of the building. these enclosures were another items that was cut out due to the money problems. so they are actually quite industrial units. At the time I wasn’t very happy with that but now I think it is what it is, it’s very exposed and shows what it does.

seagulls were an initial. it turns out that seagulls are particularly aggressive. we put bird wire up but did nothing to the seagulls. the males particularly in mating season see their reflection in the etfe and start attacking it. That was dealt with but using a falconer. we had to repair a pillow because of that.