Friday, December 15, 2017

Table of Contents for Greenitiatives





Interview - Ashok A Sanadi (SER Global)

Contemporary Indian buildings draw mindless inspiration from the western countries

 

ASHOK A SANADI, DIRECTOR, SER GLOBAL has 15 plus years of experience of working as a consultant in the HVAC and Sustainability space for leading developers and IT companies. His expertise lies in conventional and non-conventional HVAC systems, passive cooling systems design, natural ventilation and lighting systems. The Bengaluru based Chartered engineer spoke to ANUJA ABRAHAM on correct design practices to reduce load on HVAC systems.

 

There has been a lot of buzz around creating net zero buildings that are self sufficient. What is a net zero building? How does one achieve it?

To put it simply, it is a building that meets its energy demand by generating its own electricity. This is possible by generating power through a renewable source, by increasing energy efficiency through energy-efficient design methodology and by installing onsite power generation. So whatever be the power demand, they will be generating their own energy, which will make it net zero. Even during construction, take in processes like transportation, breaking and crushing stone which have embodied energy. Embodied energy is the total energy required for the extraction, processing, manufacture and delivery of building materials to the building site. Non-renewable energy like thermal plants, conventional energy sources lead to carbon emission, which contributes to greenhouse gas emissions, so this type of energy is considered an indicator of the overall environmental impact of building materials and systems. We counteract that by making changes in our design. The basis of design shall be by assessing the one-time energy consumed for transporting the materials which includes fuel consumption, process extraction etc and also the operating demand per year. We calculate the total energy consumed for the embodied materials and oversize the renewable energy generation apart from their operational demand and accordingly generate excess power, which we can also supply back to the available grid, making it net zero and also makes it a carbon neutral building.

 

What are the steps involved in Net Zero building designs?

The steps involved in the design of a Net Zero energy building comprises detail climatic analysis of the city or location to understand the potential of natural ventilation and alternate cooling or heating systems. Other things taken into consideration are passive solar design for reduction of solar heat gain and optimal utilisation of daylight at the same time.

The selection of locally available, thermally efficient, low embodied energy building materials is an important factor as well. Passive right design and appropriate selection of building materials will ensure the first step of reducing the building energy demand. The design of project, MEP system has to be intelligent with the use of controls to take tangible benefits from passive right design. This approach will reduce the connected energy and annual operational energy consumption of the project. The client can also go for macro level renewable energy investments if possible and utilise grid power at his source, whatever may be the renewable energy type, integration type and use. So in all, passive right design of building, selection of low embodied energy of materials, design of efficient and intelligent MEP system remains the key for efficient and economical Net Zero energy building success.

 

Please share a case study of a net zero project you’ve worked on.

I have worked on a Renewable Energy project called HAREDA (Haryana Renewable Energy Development Authority). The 40,000 sq ft office building at Chandigarh doesn’t use any power grid connection. In the design we have reduced the energy requirements to 25 per cent by adopting energy efficiency methodology and this energy is generated onsite by renewable sources. Apart from energy, water is harvested and makes it a water efficient building also. This project was rated a 5-star GRIHA project and won an award for the best energy-efficient passive building in India.

 

Which other landmark projects have you worked on?

I have worked on Infosys Mysore; the LEED certified project saves around 50 per cent energy annually. I have also been involved in the INFLIBNET project, which is an approximately 2.5 lakh sq ft digital library in Gandhinagar, Gujarat. It saved 60 per cent of energy compared to the ASHRAE benchmark. We have used underfloor air distribution system with 2 stage evaporative cooling system, and the temperatures remain at a convenient 26° C even in summer.

Also, some of the other on-going projects are Infosys Bhubaneshwar, Bangalore International Centre, Infosys, Nagpur, etc.

 

Can you explain the efficient designs of the IT buildings?

Glass plays a major role in transmitting and trapping heat inside any building so cutting down on the overall area of the glass is crucial; also orienting the building also plays a major role in reduction of heat generation. So in the design we need to adopt the envelope heat reduction through using wall insulations, creating cavity walls, reflective paints for external façade, roof insulation, shading of windows, day light harvesting etc. All these measures can be assessed by using computer generated modelling. In HVAC designs we can also look at radiant cooling systems, water cooled systems, passive cooling systems, Earth Air Tunnel systems and Ground Source Heat Pump systems.

 

Tell us about the present construction methods in India and how is it affecting the energy efficiency of the structure?

Contemporary buildings in India draw mindless inspiration from western countries. In western countries, it makes sense to use glass facades as it traps heat and insulates the building in colder climates. Solar radiation travels in the form of light but when it is in contact with an opaque object it turns into heat. Opaque objects like walls and roofs, by nature, allow less heat to pass through compared to glass. In an environment where glass facade is used, it is likely to cause discomfort to inhabitants by causing glare on the computer monitors. And the minute someone draws the curtains, it causes a two-way problem, one is that it has already trapped the solar heat indoors, thereby increasing the cooling load on the air conditioning; secondly, one’s dependency on artificial light increases as natural light is completely blocked out. That too increases the energy consumption of the building.

 

So which are the most commonly recommended cooling systems in India?

In India the most conventional systems are water-cooled and air-cooled chillers, but when it comes to energy efficiency the designers need to look at the suitable energy-efficient system for the particular building and particular climate. Some of the energy-efficient design can include as water cooled system, radiant cooling/heating systems, earth air tunnel systems, ground source heat pump, solar operated chillers, vapour absorption chiller systems, thermal storage, heat recovery wheels, passive cooling technologies, stack ventilation/natural ways of ventilation, etc.

 

In a crowded city like Mumbai where land is a major constraint, what cooling systems would you recommend?

Nowadays every city for that matter has an issue of land scarcity because of developments. It is recommended that we adopt energy-efficient methodology to save on the infrastructure requirement itself at source. Then we can also look at the designs which are feasible for a particular project.

 




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