Office Building
for TSREDCO and TSSPDCL, Hyderabad

Summary

Location Hyderabad, Telangana
Coordinates 17°24’45.2″N 78°27’36.8″E
Occupancy Type Office
Typology New Construction
Climate Type Composite
Project Area 5116.5 m2
Date of Completion 2024
Grid Connectivity Grid-Connected
EPI 58 kWh/m2/yr
Architect Ashok B Lall Architects
MEP Design Guidance Prifactors Engineers
Energy Consultants Effin’Art Sàrl

The Telangana Government and the Telangana State Renewable Energy Development Corporation Ltd. (TSREDCO) are jointly engaged in the development of a grid-interactive net-zero energy office building in Hyderabad. This six-story office, jointly utilized by TSREDCO and the Telangana State Southern Power Distribution Company Limited (TSSPDCL), is currently progressing towards becoming India’s first grid-interactive super ECBC-compliant Net Zero Energy Building.

The building is designed to be highly energy-efficient and is a grid-connected building that meets its energy needs through renewable energy while keeping a two-way communication with the grid to balance demand with the electricity supply. Demand flexibility is integrated in the building enabling it to respond to load profiles of the utility and contribute towards curtailing demand during peak periods. The project also will generate power on-site through a 179 kWp roof-top solar power plant; generating 271360 kWh units annually.

Technical assistance to this project is being provided under USAID’s the South Asia Regional Energy Partnership (SAREP) program.

Office Building
for TSREDCO and TSSPDCL, Hyderabad

Climate Responsive Design

In the building, services are located in peripheral zones providing protection from dominant South-South East/West-North West irradiation. The service area comprises 20% of the total area.

Thermal Mass

To maintain a compact building design, the ratio of the surface area to volume is kept at a minimum of 0.25.

To minimize the exposed external wall area, the ratio of Gross Floor Area (GFA) to the external envelope area of the building is 1.98.

The RCC floor slabs become a thermal flywheel tending to maintain the weekly mean dry bulb temperature (DBT). It also acts as a thermal store for night flushing as well as a cool store for radiant cooling pipes embedded in its mass. The entire cool mass is well insulated.. Insulation is laid under the flooring of the ground floor office area to complete the insulating envelope. There is no thermal bridging between external surfaces and shading attachments.

Building Envelope

The service areas are located alongside northwest and the southeast facades that receive the highest irradiation. Considering that the northeast facade offers unobstructed views of Hussain Sagar lake (from higher floors), and it receives the least irradiation, there is minimal shading on this surface. The southwest facade features external movable shading for year-round solar and glare control and provides access to westerly breezes. This design maximizes the SW facade extent, with 60% of it well-shaded by the courtyard.

AAC blocks used in the building help to reduce the weight of the structure while also thermal insulation. The flat slab structure in the building requires 10% less reinforcement steel compared to conventional office building structures. Both of these contribute towards reducing embodied energy of the building. 

Daylighting

The fenestrations have been optimized to maximize daylight while minimizing heat gains. 

To make sure there’s consistent daylight in the building on each floor, the floor-plate depth has been limited  to 6.5-7m for single-sided windows and 13-14m for double-sided windows. This setup ensures at least 60% of the floor area receives useful daylight (100-2000 Lux) for 90% of regularly occupied hours.

The building also effectively controls glare with courtyard and external shading, and the distribution of daylight across the floor is even, minimizing glare spots to 0.9% (Annual Sunlight Exposure) . In the office space where computer work is the primary task, 100 lux of uniformly distributed daylight is sufficient, eliminating the need for artificial lighting.

Shading

The project has two main facades: the NE facade has horizontal shading for morning and summer heat, while the SW facade has a combination of horizontal projection and vertical fins to cater to year-round afternoon exposure. There’s a drop-down louvre system for afternoon sun in winter until 16:00 hrs. These strategies result in NE shading equivalent factor of 1.42 and SW of 2.4, achieving an SHGC of < 0.15, exceeding Super ECBC requirements.

Ventilation

Monsoon breeze is captured by opening the window on the southwestern windward side and is allowed to flush through and exit on the opposite leeward side of the building. Ventilators are provided above the doors. The top light panel over the windows is also a ventilator. This will enhance ventilation during the winter seasons by stack ventilation. Toilets and staircases are naturally ventilated and segregated from the office space.

Landscaping

On the building site, 100% of the landscape area is planted with native vegetation..

  1. Along the site boundary, native flowering trees like Saraca asoca, Erythrina indica, and Bauhinia purpurea will be planted.
  2. The sheltered courtyard will have tall and short palms, along with lilies in the water feature.
  3. The front facade will feature planter boxes with flowering and evergreen plants.

Office Building
for TSREDCO and TSSPDCL, Hyderabad

Lighting

In the building, artificial lighting is not needed during daylight hours, except on overcast days. The lighting system is designed to provide an even illumination at 100-150 LUX for general use. If more light is needed, occupants can also use task lighting.. The building will adhere to the lighting control guidelines specified in ECBC 2017. It will feature the following:

  1. Efficient LED fixtures to achieve a Lighting Power Density of 2.47 W/m2, surpassing Super ECBC requirements by almost 50%.
  2. Lamps with an efficacy of more than 100 Lumens per Watt.
  3. Smart lighting systems, specifically DALI (Digital Addressable Lighting Interface), enabling individual control of each light fixture for increased flexibility, energy efficiency, and functionality compared to traditional lighting.
  4. Occupancy sensors.
  5. Daylight sensors in all naturally lit areas.
  6. Scheduled controls for internal and external lighting.

Residual Cooling Demand Strategy

In the building, fresh air will be supplied from central Air Handling Units (AHUs) located on the roof, with one AHU for the East wing and another for the West wing. These AHUs use a combination of heat recovery and desiccant wheels at the exhaust and intake. The fresh air can also be further cooled using a chilled water coil, and the desiccant wheel is recharged by a heat pump connected to the return pipe of the radiant cooling system. Additionally, a chilled water spray in the exhaust air path improves the heat recovery wheel’s efficiency.

Sensible cooling will be achieved by using cool water with a temperature near the Wet Bulb Temperature (WBT), produced by a highly efficient cooling tower. This cool water cools an insulated water store, which then feeds the radiant cooling circuits.

To circulate fresh air in the office spaces, Floor AHUs are used with a low-pressure displacement ventilation system.

The building utilizes the following heat transfer devices:

  1. Radiant Cooling.
  2. Indirect Evaporative Cooling for fresh air.
  3. Heat Recovery and Desiccant Wheels.
  4. Heat Pump for Desiccant Regeneration, utilizing heat from the radiant return circuit.
  5. Low-pressure Displacement Fresh Air Ventilation.

Strategy for Further Reducing Irrigation Water Demand 

Highly efficient irrigation equipment like micro drips and micro sprinklers will be employed. Additionally, water-saving methods such as pot irrigation will be integrated.Collectively, these techniques and focus on native vegetation will reduce the water demand for landscaping to an average of 2.5 liters per square meter per day.

Bio STP – Reed-bed system

A reed bed Bio Sewage Treatment Plant (STP) is being proposed for this project for several reasons. Its energy consumption is significantly lower, about 80% less than a mechanical STP. The only energy required is for pumping water to the reed bed and from the treated water tank to the roof.

Reed bed STP is a natural and low-maintenance solution, with regular attention from a gardener needed to care for the plants. It can be seamlessly integrated into the landscape since the surface of the reed bed is covered with plants. This type of STP provides secondary treatment for wastewater and can directly contribute to landscaping. Approximately 70% of the total wastewater will be available for various uses after being treated.

Building Management System

The building will feature an advanced Building Management System (BMS) to optimize its efficiency, monitoring and controlling various functions, including lighting, HVAC, security, and energy management. The Building Automation System (BAS) includes Network Server/Controllers, Digital Control Units, Administration and Programming Workstations, and Web-based Operator Workstations. It provides control, alarm detection, scheduling, and reporting. The system can offer web-based automated predictive energy optimization (APEO) and support local utility Demand Response (DR) programs. It uses communication protocols like BACnet, LonTalk™, or Modbus for seamless operation.

Office Building
for TSREDCO and TSSPDCL, Hyderabad

On-site Energy Generation

The renewable energy system designed for the building has an installed capacity of 160 kWp, resulting in an annual energy generation of 271360 kWh. The system has a performance ratio of 76.5%. It utilizes a Fixed Tilt rack type set at a 4-degree flush mount, oriented towards the southwest. This configuration ensures optimal solar capture.

The cafeteria in the building will utilize hot water generated by solar photovoltaic (PV) panels, and renewable energy for heating purposes.

Metering

The LT Meter installed will have the capability to record demand in kVA, energy consumption in kWh, and total power factor. Additionally, it will display current values for each phase and neutral, voltage measurements between phases and between each phase and neutral, and total harmonic distortion (THD) expressed as a percentage of total current, in accordance with ECBC requirements to prolong the lifespan of electrical equipment. The metering system will be grid-interactive to facilitate communication and interaction with the on-site generated solar power.

Sub-metering will be implemented for various end-uses, including:

  1. HVAC equipment and systems.
  2. Electrical equipment.
  3. Lighting.
  4. Individual floor power circuits.
  5. Water treatment plant.
  6. Sewage pumping.
  7. Hydrant pumping.

Office Building
for TSREDCO and TSSPDCL, Hyderabad

The Telangana State Power Distribution Company (TSSPDCL) is initiating a Demand Response Program (DR). During a DR event, TSSPDCL will send specific signals (SMS) as outlined in the program enrollment contract, which can be related to price, reliability, or supply and demand.

Key recommendations include:

  1. DR enrollment for a minimum of one year through a contractual commitment, with the potential for multi-year renewals, covering at least 10% of the estimated peak electricity demand.
  2. Develop a comprehensive plan to fulfill the contractual commitment, addressing roles, responsibilities, system details, procedures, processes, reporting, training, and internal risk management.
  3. Implement a building management system capable of real-time, fully automated DR, initiated externally by the power distribution company.
  4. Ensure the DR system can receive and respond to external signals generated by the power distribution company.

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