Some exhibitions now need 1·5 MW of power to light and run the shows, and concerts can concentrate as much power and equivalent heat as a queue of 250 London taxis in a single lighting gantry. Coupled with the fact that seven out of the ten hottest years on record in London have occurred during the 1990s, Earls Court's original free cooling ventilation system has come under increasing pressure in recent years.
The Earls Court management team commissioned FaberMaunsell to look at how the ventilation system could be improved without major refurbishment work or other disruptions to the forthcoming schedule of events.
Initially the team decided to address the problems being experienced in the newer area. Earls Court 2 was built in 1989 as an extension to the original halls. Although newer, it has still been affected by the rapid change in exhibition power requirements and the effect of environmental change on the structure.
A deadline of August 2000 was given to resolve the comfort cooling issues here. August was chosen as is it traditionally one of the hottest months of the year, and because two of its highest power consumption shows – The Watchmaker and Jewellers Convention and The Plasma Show – are held then.
FaberMaunsell's in-house r&d department made extensive use of computational fluid dynamics (cfd) to research Earls Court 2's temperature and airflow profiles. This involved generating a computer model of the building, then inputting various data to get a pictorial analysis of the resulting airflows. The results of the analysis supported the need to improve ventilation in the building and to add comfort cooling.
Mike Maslin, FaberMaunsell's project manager says: " One of the main challenges with assessing the ventilation systems for Earls Court 2 was to take into account the variety of uses for which the building is put to and plan the installation work around the events being held. The original ventilation system provided filtered and tempered air and worked well up until the 1990s, but cooling needed to be added as the amount of power and lighting used and the resultant heat generated increased every year. With the use of our cfd model we also looked to make improvements in the air distribution to deal with the various exhibition layouts."
Following extensive research into the most appropriate form of cooling, three 850kW McQuay air-cooling water chillers were installed at roof level on a crossover link between Earls Court 1 and 2. Noise control, ease of maintenance and public accessibility all played a part in the decision. No large plant was on the roof previously, so this was reinforced from below with secondary steelwork before work began.
Because of Earls Court's proximity to residential areas and the variety of concerts held at the venue, a noise limit of 32 dB(A) was set for night-time operation of the chiller plant. Acoustic surveys were carried out by FaberMaunsell before and after the chiller installation to ensure the plant met the specified criteria.
This first phase was completed ahead of schedule in July 2000. At that year's Watchmakers and Jewellers exhibition temperatures were maintained below 21·5°C during the exhibition, which compared to over 26°C the previous year. With over 100 m3/s of cooled air serving the area, comfort conditions were guaranteed.
Following this installation, clearance was given to go ahead with the more complex ventilation and cooling needs of the original Earls Court 1.
Earls Court 1 - The story so far
In Earls Court 1, the main central hall spans 76 m, is 122 m long, 35 m high and contains close to 300 000 m3 of air. When the original ventilation system was designed the problem was faced of providing an adequate and stimulating distribution of air, while satisfying the requirements of the London County Council in terms of smoke extraction.
The solution involved eight air handling plants equally spaced about the 396 m perimeter. Each was capable of providing a powerful blast of air through six, high-level nozzles directed parallel to the seating slope and some 3 m above this. The nozzles introduced large quantities of air into the arena at a throw of about 40 m.
Two-thirds of air extraction in the main hall was achieved by ducts under the first and second floor galleries at the sides of the hall, with the remaining one-third through lighting slots in the false ceiling. The extracted air passed into the roof space and recirculated back to the air plant. By control of the motorised dampers the desired balance between fresh and recirculated air could be maintained.
During exhibitions, the manual dampers on the high level nozzles could be shut off, and the air inlet into the hall was achieved by reversing the direction of airflow through the ducts under the galleries at the edges of the hall. At the same time, the dampers controlling the extraction from the roof were opened wide, so that all the air was extracted from the top of the hall as required to meet the LCC regulations of the time.
For this area, the old system has been maintained and is working side by side with the new process to provide the best ventilation solution for current needs. The original plans were used to analyse the structure and existing ventilation systems, and the latest airflow technology to complete the design. To make best use of the new Earls Court 2 chillers, the consultant proposed using them to pre-cool the extensive concrete mass of Earls Court 1 at night. "Using our dynamic thermal model we were able to demonstrate a night cooling solution in Earls Court 1 would work. Together with the very quiet Mcquay chillers, this gave us the opportunity to maximise the existing cooling plant capacity," says Mike Maslin.
The internal temperatures in the main hall are allowed to rise during the day from 18°C to 23°C in the late afternoon, while temperatures in Earls Court 2 are controlled to similar levels with the chiller plant, maintaining comfort conditions throughout the complex.
A third phase of the project saw an additional 1 MW McQuay chiller installed, providing a total of 4 MW of cooling and affording comfort conditions to the both main exhibition halls. "By increasing the overall cooling capacity, both halls can now be cooled simultaneously," explains Maslin.
The building could not be closed so the work had to be carefully planned and co-ordinated. Keith Shenstone, technical director of principal contractor Meica explains: "We had to liaise closely with Earls Court to make certain equipment deliveries were timed to cause minimum disruption. There are timeslots following large shows to dismantle the show stands which could be used."
Most of the work was based at roof level so access for deliveries was the largest concern. "If we had a day allocated for a crane we had to stick to that time," says Shenstone. This fact, combined with limited storage area at ground level, meant materials were lifted to a landing platform on the roof on delivery days, then distributed from here as the work progressed.
"The planning of the job was the key to its success," stresses Shenstone.
Source
Electrical and Mechanical Contractor
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