Architecture & Design

Architecture & Design | 25 ensure ample commercial space while allowing natural light to permeate between the buildings. The towers are juxtaposed to provide a framed view, with gentle curved façades to soften the height of the development. As the design developed, the designers reviewed the vista of the towers from the main piazza and eateries around it. In order to present the four towers as one whole architectural piece, a series of walkways and bridges on the lower levels were then incorporated to connect the four towers and bring them together as one, directly also greatly improving the spatial quality for the lower levels. Ultimately the design team is quietly confident that The Quad looks set to be a highly photogenic building with diverse facade treatments and diminishing volumes as it rises upwards, certainly holding its own in any European financial district. MEETING THE STRUCTURAL CHALLENGES HEAD ON Bruno Finzi, Founder and Managing Director, CEAS Milan The QUAD project represented a challenge, both from a geotechnical and structural engineering point of view. The presence of four underground floors and a large excavation in an already developed and built area has required a peculiar geotechnical design to allow a forecast of both short term and long-term settlements, and to allow for the design of the retaining walls and foundations of the four towers. A tailored monitoring of topographic displacements both for the existing buildings as well as for the excavation peculiar points has allowed the direction of works to verify, in each construction phase, that the geotechnical design had reached and respected the targets. The structural design provided for some massive concrete raft foundations for the towers that necessitated a well-tested mix design for concrete in the attempt to reach a low heat of hydration. The design of slabs involved high design optimization, with the target of limiting masses and structural thickness; the choice of a lightening system inside the concrete slab required an accurate execution where three different concrete layers were cast in sequence: below, aside and on the top of the lightening systems. The limited structural thickness of slabs, while allowing for a better architectural interfloor height and an easier HVAC distribution, represented a challenge due to the large spans and cantilevers dimensions. These structural slabs are also fundamental in sustaining the glass façade systems. Prefabrication has been used mainly for the underground floors while the main bracing systems for the towers are represented by the staircase cores that are built with cast in situ concrete. Another structural challenge was the steel bridges connecting the four towers. The architects provided a fantastic structurally sound design and layout that allowed for a construction that could be preassembled in parts, and erected and connected on site. With this innovative design we faced almost all the structural challenges conceivable from excavations, foundations, use of prefabrication, type of formworks, erection and building timing and I believe all were met and solved through a great collaboration between the design team and the contractors entrusted with this project. A SUSTAINABLE APPROACH Paul Borg Senior Architect, DeMicoli & Associates The project at The Quad placed sustainability at the fore front of its agenda from inception, with integrated sustainable design features aimed at reducing energy consumption. American consultants were engaged at very early stages, to guide all the other consultants on the requirements needed for the development to achieve Platinum accreditation with LEED. After three years, the project is well on its way of achieving this goal. Among the many measures required to achieve a high-quality sustainable building, in its day to day running, is water storage. A reservoir, with a capacity to hold 1900 cubic metres of water, was built to contain the majority of the rain water. A smaller reservoir of 931 cubic metres was also constructed at the lowest basement levels and will serve to be used in firefighting emergencies, irrigation purposes and in a dual flush system. Alongside these reservoirs, the project incorporated a Grey Water Treatment plant which will treat water from wash hand basins and showers and after treatment, the same water will be used in the flushing system. This plant will generate about 100 cubic metres of water during the summer months and 60 cubic metres in winter. One of the bigger challenges has been the waste management during construction and subsequently during operations. Waste separation has been carried out by the different contractors during the works. The development was also bound by a Planning Authority permit condition where an independent body holds weekly site visits, checks the issues related to permit conditions and site management and reports to the Planning Authority. This has proven to be an effective tool to drive a much more organised and clean construction site. A team of people employed directly by the development, also constantly monitor, and clean the site and enforce health and safety regulations. This has ensured that the site has been maintained to a high level of cleanliness and safety during the construction, servicing and finishing periods. To adhere to the strict guidelines required by LEED, the reflective index and the insulation properties for the glazed façade are of a very high standard. This is even more important since the four towers are nearly completely clad with a curtain wall system composed either floor to ceiling panels or a curtain wall system suspended off Halfen brackets with some of the glazed panels as large as 4.75m in height and 1.7m in width. The project incorporates a vertical photovoltaic panel system which cover a solid wall of one of the towers for the whole height of fifteen floors. The PV system has a capacity of over 110kWp and it is estimated that it will generate 120,000 units (kWHr ) of energy annually. This is just part of a sustainable lighting system where all the light fittings being used are LED and the design includes of low level and downward looking lights which will prevent any light pollution emitted from this large site.

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