The World Towers is the large-scale residential development by Lodha group in Mumbai. Buro Happold Engineering using new technologies applied a sustainable design format to maximize performance and efficiency of the project. Krishnendu Mukherjee, Group Director – Building Services, India at Buro Happold elucidates.
Buro Happold is a multi-disciplinary engineering consultancy company that started in the year 1976 in UK. The company has offices across the globe and its first project in India was the Sahara Stadium. In 2008 starting from a small set-up in Pune, the company next year shifted base to Mumbai.
That was also the time when the scales of projects in India were growing horizontally as well as going vertical. Most of these complex projects are associated with international architects and engineers. Evidently, in terms of providing skills to the building industry, the global exposure has brought forth a transformation in the Indian real estate.
Taller the building higher is the cost to build and operate the building. Rom a developer’s perspective for a tall building, it is important that the income meets cost.
Key drivers for efficiency in tall buildings
Tall buildings house a large numbers of occupants, consumes huge amount of energy and water and generates large amount of waste. Irrespective of plan, shape and location, it can be said that construction and operating cost for high rise buildings increases significantly with increase in height.
The Plant Strategy:The spatial efficiency is linked to vertical distribution and plant floor locations.The building core contains the vertical distribution of MEP/Building Services system throughout the building. Optimizing the cores & risers and maximizing net to gross floor areas increases efficiency. .
In general, increasing the number of floors between technical plant spaces will increase the size of distribution risers. This is because the services running through the risers at each floor level are required to serve a greater number of floors.
Defining a plant distribution strategy therefore becomes a balance between how much floor area is lost to become technical plant space and how much of each occupied floor level is lost to the risers required for services. The efficient plant distribution strategy involved placing water tanks and transformers at basements and at high levels, as required and applicable Tall buildings.
The System Hydraulics:Static pressure at any point is proportional to the height of the water above it, remembering that pressure acts equally in all directions. In a pipe work system one can imagine the vertical pipe rise as effectively a column of water where the static pressure acting in all directions at the bottom of that pipe is proportional to the height of water above.
Final calculation of the pressure in a system must add this static pressure to the dynamic pressure created by the circulating pump as it overcomes the frictional resistances within the pipe work system. Technical spaces at specific levels of the tower allow hydraulic separation of the water systems which allows these pressures to be controlled.
- The pressure in a pipe work system must be within the safe operating pressure of the equipment and components used. Standard equipment and components are generally designed to operate at a maximum of 16 bar using PN16 pipe work and fittings.
- Higher pressure rating components are available but the cost of these are high and there are safety implications involved in the construction and maintenance of high pressure systems, this includes the risk of the wrong component being installed if different component pressure ratings are used on the same site.
Sustainability: A sustainable design approach in tall buildings helps achieve the project and energy cost efficiencies. The development should be self-sufficient to the extent possible in meeting its energy & water requirement and waste management to reduce burden on city utility infrastructure.
Also, assessment of existing conditions around the project enables ascertaining the existing and planned infrastructure for power supply & distribution, gas, potable water supply, storage, distribution, treatment, sanitary drainage & treatment, storm drainage etc.
Compared to other parts of the world, building tall buildings in India is challenging, as they understand the complexities of making tall buildings. When you are making a 100 stories tower, you need to visualize the whole image of the building. Not enough time is given to the integrated design which creates executional problems later.
The Indian Scenario
In India, tall buildings are fast coming up in major cities. Mumbai has more than 100 projects which are 50 stories or more.Most of these tall buildings are designed to be at par with the green buildings in USA and UK. However, there is a lack of homegrown expertise as it is a new trend. Skilled manpower for construction too is a constraint.Therefore we see lot of international architects, contractors and engineers working on these projects.
City infrastructure is another major challenge. Most of the tall building project developers are providing for utilities and waste management within the premises yet the connectivity and last mile facilities are dependent on city management. So cities infrastructure augmentation is necessary to support these modern buildings. The building bye-laws too need to update as per the newer technologies & construction, which is gradually happening. The laws governing real-estate are currently inadequate and inconsistent. They need to be streamlined.
Employing best engineering practices and spending more time planning is imperative in case of tall structures. The green building consultants, fire engineering consultant, wind engineering consultant, lighting consultant and other experts should be on board right from the planning of the development.
The World Towers, a 17-acre private estate in Worli, Mumbai comprises three towers – World One, slated to be world’s tallest residential tower soaring above 1400ft and World Crest & World View, the tallest towers in the country. It is the first large-scale residential project in Asia to have interior design by Armani/Casa.
The Project Engineering: It builds on sophistication of design, energy saving and advanced construction technology. Building Information Modeling (BIM)platform was used for plant room and site MEP infrastructure co-ordination.
M-95 concrete has been used for the first time in the construction industry in India in this project. The Jump-form shuttering vastly cuts down jump cycles, enabling the tower to rise at a peak speed of five days/floor. Additionally, the mechanized formwork system for the construction of the entire floor plate area assures concreting of all columns and walls in a floor at a six-day interval.
For protecting tall towers from lightning damage, the steelwork within reinforced concrete structures has been uses as down conductors for lightning protection.
Similarly, India’s fastest elevators installed in this project are capable of speeds of up to eight meter per second.
Microclimate Analysis: Investigating the local microclimate helped understand how to maximize the day lighting and wind and solar energy for the development. Based on the existing conditions assessment and site microclimate analysis, site wide energy, water management and waste management strategies were being established and implemented.
Some strategies used were:
-Optimize building mass and orientation
-Maximize daylight to reduce electrical lighting load requirement.
-Maximize passive ventilation to reduce mechanical ventilation requirement.
-Minimize solar gain and maximize shading to reduce solar heat gain and air-conditioning load
The engineers explored the available solar radiation (direct and diffuse) throughout the year for generating solar hot water and street lighting to meet part of development’s hot water and street lighting requirement. This is cost efficient and also clean energy.
The rain water harvesting feasibility report included analysis of rainfall intensity, quantity and consistency throughout the year for harvesting rain water to meet full or part of the project’s potable or non-potable requirement.
The Sustainable Approach: Known for having designed the Louvre at Abu Dhabi, Buro Happold and the design team holistic approach focuses simultaneously on concepts, details and execution. The Mean, Lean and Green model for World Towers was built to attain sustainability not just once the project is completed but also at the time of construction.