When the building needs to remain operational

Cidade Mall, located in the centre of Belo Horizonte, has gone through three expansions since 1991. This year it will undergo a complete retrofit including aesthetic changes. All facilities inside the building will also be modernized. In total there are six floors of shopping area resulting in 62,400 m² of built surface on a plot of 7,500 m².

Text: Luciana Tamaki

The different jobs are carried out in several stages, whilst it is not acceptable to close down the mall and refuse access to the 80,000 daily visitors. Since the start, which was approximately eight years ago, a number of jobs have been successfully completed including a complete upgrade of the electrical installations. The air-conditioning system conversion to CCW  (central chilled water) is about to be completed.

Necessary changes

The mechanical design is aimed at the revitalization of existing facilities, which include: a CCW air conditioning system existing of two chillers with centrifugal compressors, low noise cooling towers, a set of primary and secondary pumps for the cooling water circuits, and a set of pumps for the condensation circuit.

The director of Climatizar Engenharia, Francisco Pimenta, says that with the optimization and increased reliability of the air conditioning system, one CCW was designed with three chillers, with a compressor type "Bolt" offering high efficiency and a unit capacity of 550 TR. The same applies to the cooling towers, however, these cover the exchange of all pumps for the in-line type and frequency inverters - "It contributes significantly to the perfect fit of the water flows and savings in energy consumption," says Pimenta.

In full operation

As the mall has to remain operational, it was essential for the systems to continue functioning properly. "The bottom line was to redesign the complete CCW unit without making it stop working. That alone made this job very unusual and brought along additional complexity," as stated by Pimenta.

The execution of this job is taking place primarily at night, in very detailed defined steps. For example, there are several steps of interconnecting new pipes with existing ones and moving in new bulky equipment to replace the existing equipment.

The advantage of BIM models

One of the great contributions of BIM to the designers was the complete overview of the existing situation and the viability of proposed design changes from the beginning up to the completion of the job. As this was a retrofit, it would have been very difficult to implement a design using only floor plans and cross sections coming from traditional CAD drawings. "We had to consider existing pipe routes and reuse them. Furthermore, we had to make bypasses at strategic locations. It was easy to visualize the possible solutions, which was a great benefit to us, "says Pimenta.

Another advantage is not directly linked to the design process. Whilst, with the BIM model, the engineers could show the client the existing situation and take them through all design stages using 3D visualizations. "We even created an animation showing the complete CCW unit in the technical room", says Pimenta. This was crucial to the understanding of the solutions presented to the client.

How was the BIM software choice made?

The designers of Climatizar Engenharia adopted DDS-CAD for just over one year, and this is the only BIM software they use. "What led us to use DDS-CAD was especially the ease of use and its intuitiveness of designing MEP systems", says Pimenta.

An additional advantage of the software is that, compared to other BIM software, DDS-CAD is much lighter and runs smoothly on standard hardware. Furthermore, as Pimenta indicates, "DDS-CAD is not an architectural tool with some MEP features on top of it. The software is specifically tailored to MEP engineering and supports the processes that we engineers apply in a BIM workflow".

DDS-CAD in Brazil

Together with other pioneering companies in Brazil, Climatizar Engenharia is closely working together with Data Design System to further localize the software. "As always with new software, we faced some challenges at the beginning. But Pimenta stresses the major gains that are achieved in the design process. If there is a conflict, for example, between two ducts, DDS-CAD instantly solves it. This significantly improves the quality of our designs.

"The urge to change from using CAD drawings to BIM models in projects is evident in our market. The delivery time for projects decreases each year and the need to have reliable and consistent output becomes more and more important", explains Pimenta. For this reason, even if the change in the way of working requires "courage and patience", as he himself points out, "we have to leave our comfort zone and embrace new innovations."

The advantages seem clear to the designers, Pimenta reflects on the use of BIM models at the construction sites. "Today, there are not many professionals who know how to use the BIM information correctly, I believe this is a point that will take longer." But Pimenta stresses that the gains for construction companies are huge, because of the richness of data inside a BIM model. "They only have to understand and experience how they can effectively make use of it."

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