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Journey to the Centre of the earth An underground building with requirements for minimal lighting and efficient ventilation made for a complicated but interesting project. Words by Declan Leonard, building services department manager at PM Group
The Cliffs of Moher Visitor Centre was an extremely difficult project as essentially the building is subterranean. There was very little room in terms of areas for services, so all services and distribution had to be integrated into the structure itself. As the architect had specified a cave-like finish, there was no surface-mounted services – everything is run within the walls of the structure, a job that obviously took a huge amount of coordination. The services had to go in with the reinforcement before concrete was poured. A 120 kilo watt ground source heat pump
22 – Construction Engineer
gramme where we create the building and the mechanical systems and simulate how they run. Natural ventilation was explored and then discounted for two reasons – the large numbers of people coupled with the fact that the building is underground made natural ventilation virtually impossible. The next step was to select the most efficient way of mechanically ventilating the building. The reason we didn’t go for any radiant systems such as underfloor heating or radiant cooling was again due to rapid temperature fluctuations that would occur due to occupancy patterns and the large amounts of people visiting the centre. Radiant systems would need to react quite fast so we opted for an efficient air system – the fans all ramp up and down depending on temperature and also on CO2. If there are very few people in the space, the fans will ramp down to minimum supply.
In terms of lighting, a Philips lighting control system was installed in the building. Each area of the centre has its own control panel. Quite a lot of feature lighting was used to bring up the cave-like structure, however there was a very deliberate attempt to keep a lot of the areas quite dark or dimly lit. In certain areas all we have is emergency lighting. We were conscious that we had to provide the minimal lighting required in a public building but we were still trying to limit the amount of lighting we were going to provide. It was a trade off between getting the aesthetics right and maintaining the atmosphere of the “cave” while adhering to health and safety regulations. A solar ray system provides 60% – 70% of the annual hot water energy requirement, an obvious benefit during the summer tourist season. A new waste water treatment plant was
also built as part of the project, which means that we’re taking water from that plant and sending it back up to the building where it’s used for urinal flushing and to water the roof of the building to keep it green. Therefore, we’re reducing the amount of water we’re consuming. One of the most innovative features of the project actually arose from the fact that we couldn’t take the air in through the side of the building, we had to take it from further back up the hill. So the air actually comes in through concrete ducts which are buried 15m under the ground. The air that travels along the buried pipes takes heat from the ground before it actually enters the building. We found that we were picking up temperatures in the order of 4 – 7° before the air even hits the building, so in itself that’s probably the most sustainable feature in the building.
was installed that acts as both a heating and cooling system for the building. The air system is delivered by seven air handling systems; all the systems are zoned, variable air volume systems and are turned on and off depending on occupancy. They all have heat recovery wheels in them which is, I would say, about 75% efficient. In order to ascertain what kind of services needed to be installed, we built a thermal dynamic simulation model at the outset of the project which is basically a computer pro-
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