2 | CLIMATE CONCEPT

2.1 Sustainability vision

The goal of achieving sustainability has been an integrated vision for the project and has been taken into account by all the disciplines. To achieve this goal, the design focuses on the aspects of reduce, re-use, re-purpose and produce. To re-purpose spaces for future use, the structure is designed to be adaptable such that the functions can change and, instead of losing its purpose, it can adapt to future demand. As a result the towers can accommodate both residences and offices and the machines in the fabrication lab are removable. This is also taken into consideration for the installation of climate systems such that it offers flexibility and adaptability. To re-use, the waste heat is recovered as much as possible from different spaces. Moreover, the building has a Rainwater harvesting system to meet the water consumption demands to a certain extent. Grey-water recycling is another strategy to limit the need of water resource. The recycled water is supplied to the urban green hill at the plaza level for supporting the plant growth. To reduce the energy demand, the envelope is designed such that the direct solar heat gain is reduced by ensuring self-shading over the glazed portions of the facade. Possibility of exploiting natural ventilation through the facade has been explored significantly reducing the need of mechanical ventilation. In addition to passive facade strategies, efficient heating and cooling systems are provided such as geothermal heat pumps, floor heating etc., which demand lesser energy as compared to the traditional systems. The site being surrounded by an urban development is vulnerable to be affected by the urban heat island effect. Hence, the green urban hill at the plaza level mitigates the urban heat island effect and excess atmospheric CO2. This strategy also creates a microclimate at the public plaza level thereby reducing temperatures effectively and maintaining a good urban comfort in the vicinity. To produce sustainable energy through renewable resources, the facade focuses on combining architectural aesthetics with an energy efficient envelope with the PV-panels. The roof area of both the towers are equipped with solar water heaters which can significantly meet the energy demand for heating hot water especially for the hotels.

Passive climate design strategies play a very crucial role in reducing the dependence on mechanical installations and cutting down the energy demand of the building. Different such strategies are incorporated in the design at the very beginning stage of the project to help the architect and the facade designer in taking certain decisions. The overview of those strategies is provided below.

Orientation and geometry

The building geometry is designed with the aim to have a compact massing and volume to minimize the heat loss/gain into the interior spaces and to ensure sufficient daylighting into all parts of the interior spaces. This compact geometry strategy eliminates the need to add light wells for daylighting purpose. The two towers are oriented such that the longer sides face the Northwest and South-east direction thereby minimizing the exposure to the South-west direction. This strategy helps in reducing the cooling load of the towers. Since the housing function generally has more heating load than cooling load, the housing tower strategically faces the South-east side as it can receive the maximum sunlight hours during the cold winter season thereby reducing the heating load. The office tower on the other hand is oriented towards the North-west side to minimize the cooling load. (Figure 10 and 11)

Building envelope

After finalizing the basic orientation and the geometry for the two towers, it was important to optimize the facade such that it reduces the direct heat gain in all the spaces. The facade is designed in the form of triangular boxes such that the solid part is installed with pv panels facing the true south direction for maximum output and the other side of this module has glazing. The size and location of these triangular modules varies throughout the facade to provide self-shading to the glazed portions of these modules. These triangular modules act as double skin facades for the office tower and loggia spaces for the housing tower. (Figure 12)

Building form to avoid wind nuisance

In order to avoid wind nuisance at the public plaza level, the form of the urban hill has been designed with gentle slopes. As the prevailing wind direction is from the South-west, the geometry facing the wind direction is kept shorter to avoid the obstruction to the wind. This strategy reduces the vortex effect as the wind would flow around the towers rather than creating discomfort at the public plaza level. With the data centre being the central block hanging in between the two towers, the placement height of the data centre has been decided keeping in mind that the space underneath does not create a tunnel effect. The wind study has been described in more detail in the last section of this chapter. (Figure 13)

Figure10: Plan showing orientation and wind flow. (drawn by

Yamini)

Figure11: Massing diagram. (drawn by Yamini)

Figure12: Conceptual diagram showing facade layout. (drawn

Figure13: Urban gill to help with the wind flow. (drawn by Yamini)

2.3 Healthy indoor climate- building level

A healthy indoor climate is an important aspect to foster productivity, efficiency and ensure happiness and a good mental health for the users of the space. To provide a healthy indoor climate, the guidelines prescribed in Health and Wellbeing (HEA) of BREEAM international new construction has been taken into account for each space individually. This is outlined in the next chapter for each function of the building whereas the general criteria is describe in this section along with the strategies taken at the building level to reach the healthy indoor climate goal.

Visual comfort

Adequate amount of daylight and glare control in all the spaces, with views to outside is an important factor to be considered at the early design stage to provide visual comfort to the building occupants. The floor plan widths of the two towers are thus taken to be 25m or lesser to ensure acceptable daylight levels in the working or living spaces. In terms of planning, the habitable spaces are kept closer to the facade maximizing the outside views and daylight and service cores or corridors are kept towards the data center block. As per the BREEAM guidelines, all the habitable spaces should have: -the average daylight factor of atleast 1.5-2%. -a uniformity ratio of at least 0.4 or a point daylight factor of at least 0.8%

Indoor air quality

BREEAM presses on designing buildings with minimum indoor air pollution. To ensure a healthy well-being, natural ventilation has been the key to design since the initial phases. The facades of all the spaces are designed to allow minimum fresh air intake inside the habitable spaces. The natural ventilation strategy is varied for the different functions of the building and hence the facades are designed in accordance to the strategies.

Acoustic performance

The programmatic distribution has been done based on various reasons, acoustics being one of them. The programs which involve the use of machinery or robots are placed at lower levels while the workplaces and living spaces are kept at higher levels. The design thus has a hierarchy such that the more private spaces do not get disturbed by high noise levels produced at the labs and distribution centre.

A radiation analysis has been performed on the building volume on the ladybug software to understand the solar radiation falling on different faces of the building. Figure 14 shows the annual solar radiation falling in the building. Since the immediate surrounding of the site does not have high-rise buildings, the context does not have any significant effect on the radiation falling on the site. It can be observed that the highest solar radiation levels are noted on the roof of the towers and the urban hill plaza. Designing this plaza level as a green hill would mitigate this radiation level thus making the plaza a comfortable space for congregation and social activities. The South-west facades also have higher solar radiation when compared to the Southeast and North-west facades. Figure 15 shows the solar radiation analysis for the summer period. The maximum radiation is on the horizontal surfaces since the sun angle is high. On the other hand, the radiation study for winter period shows higher radiation on the South-west facade as the sun angle is low. On the basis of this radiation study, the concept for the facade was derived to design triangular module with PV panels facing the South side and the glazing facing the other side. The angle of this triangular facade module was later optimised such that the solar panels face towards maximum solar radiation. Figure 17 shows the annual radiation analysis with the facade module.

Figure14: Annual radiation. Figure15: Radiation during Summer (July to September).

The Impact on placing a Mega structure in its surrounding was analyzed using the add-in of Phoenics in Rhino. A South-western storm with a wind speed of 15 m/s on a reference height of 60 meters has been simulated as well as an average day with a velocity of 5 m/s.. Around the perimeter of the urban hill and around the entrances no dangerous wind speeds are noticed. Also at plaza level and on the hill no extreme high wind velocities are detected. The hill is slightly higher than plaza level and in this way covering the space between the two towers. Furthermore there are only a few buildings in the direct surrounding and hence the local higher wind velocities hardly have an impact on the surrounding urban comfort.

Figure18: Wind speed at plaza level.

Figure19: Wind velocities around the building at ground floor level with 15 m/s wind speed. Figure20: Wind velocities around the building at ground floor level with 5 m/s wind speed.