LIVING BUILDING

SERIES

Q & A of Living Building Series

Near Zero Dialog #01.
NetZEB Design: A step by step approach.
Presenter: Ashish Rakheja.
Partner: AEON Integrated Building Design Consultants.
Trustee: PJMT Session of April 09, 2020.

All that you wanted to know on cooling your buildings the Energy Efficient way.

GreeKnow brings you insights and directions to solutions from experts. You’re welcome to mail contact@premjainmemorialtrust.com for help. This is a listing of questions raised in the Living Building Series of online classes. This will make for more useful reading if you have watched the E Series of April 09, 2020.

The questions [and responses from experts] are listed in no order of priority and are drawn from the conversation featured in that episode. Mail us at contact@premjainmemorialtrust.com for more

Q from Sanjay Ramanujam: In a Near Zero Energy Building (NZEB), heat or coolness will be conserved. Does it impact health of inmates of the dwelling or does it enhance wellness and health of occupants?

A. You are right about NZEBs reducing heat ingress and enhancing retention of coolness. It is true that clean and healthy office air reduces absenteeism, increases human productivity by as much as 20% and improves cognitive function by as much as 101%. Providing perfect clean air while balancing energy costs is part of building design for NZEBs with both passive active elements of design and equipment

For existing buildings, a hard evaluation of existing space including air quality testing to understand the problem areas is the first step. Then would come choice of optimal solutions with right sizing of the challenge with objective to improve indoor air quality and possibly even reduce energy consumption of the building by as much as 20 percent. Choice of the right air conditioning system, optimal sizing of air volumes required to meet needs of occupants, designing ratio of air exchange, responding to temperature and relative humidity is all part of this

Ensuring choice of the right indoor plants that sequester carbon while they are comfortable in the ambience provided is part of the creative challenge.

This is especially true of schools and hospitals. Our children spend a lot of time at school. We want our little ones to learn in environments that are not only healthy but also conducive to learning. To do this, we must ensure that all carcinogens are removed from classroom air and that carbon dioxide levels are kept to a minimum. Recent studies show that lower CO2 when combined with lower pollutants improves cognitive scores by twice the norm

Q from Sanjay Ramanujam: Can NZEB be implemented in homes of truly affordable income segments. Can you give specific examples of elements that can be implemented?

A. The principles are the same. From materials you choose for construction to structural efficiency you bring with reduced use of steel and concrete; from paints and building blocks to use of floors that use less energy in manufacture; from zero water import and zero waste water export to treating waste water for drinking purposes once again ... there is a great deal that can be done.

We will soon post a few links of presentations here of many multiple and specific examples of such designed features you can incorporate in your existing buildings. Please look up https://youtu.be/PteibnIOYzs.

Of course it is a lot more cost effective if you did it right the first time with a building that is being designed. This will ensure that you take a holistic view of every material you choose to employ. For eg. using cavity blocks for external walls ensures reduced heat ingress and therefore lesser need for air conditioning. If a second skin of plants that protect walls and roofs from direct heat of sun is nurtured for the building, this obviates most often the need for air-conditioning. Constraints of your being a flat in a large apartment can be a deterrent for some of the elements. Solutions have to be evolved on a case-to-case basis. Like you need a doctor for your illness, you will need a good expert to advise you on the elements of design, costs, the right materials and solution providers and of course the right execution.

Q from Sanjay Ramanujam: Is there a repository of tested metrics relevant for India and available for benchmarking — not just borrowing from global institutions that may not be totally relevant for India.

Indeed there is. You could look up www.igbc.in or www.grihaindia.org and study the various sections carefully for what you are looking for. If you don’t have the patience or the base learning for evolving your own solutions, call in a professional who can help. Mail us and we will help you take this forward.

Q from Murali Anur: Can individual houses and villas be built as a net zero building — specifically for energy and water?

Short answer is yes. You could start with building a second skin of shade-giving trees or creeper plants. You could buy yourself a waste water treatment plant at about ₹80,000 with a capacity of 1000 litres that will treat all sewage (black water) and sullage water (grey water). This treated odourless water can be used for your garden and washing of vehicles. If you spend a little money (about ₹30,000) for a 2-bedder house and retrofit a dual plumbing system you can use the treated water for your flush tanks. You can install a two KW solar PV panel on your rooftops if you’ve enough sun beating down your roof between 10 am and 4 pm. You can charge your UPS system with it and add a couple of batteries more to store the solar generated energy for use in the nights and the morning. Have a simple rainwater harvest system that directs it to your open well if you have one — create one at a cost of ₹30,000 or so and drive all harvested water to this well and you’ll see how it helps in the non rain days with water it starts yielding by the second or third year. Get your neighbours to do such wells so that the entire area you stay in can strengthen the shallow aquifer. If you don’t want an open well to be created just divert the water to the existing borewell if you have one. All wet waste at home can be put into a zero energy waste treatment system that gives you rich compost every ten days or so. It costs less than ₹5,000. If you’ve air conditioners install an energy-saver at about ₹7500 and recover the money in less than a year of its installation while it continues to save you money on energy bills for many years after. The mantra is — energy-water-waste-air.

Q from Dr H B Nagaraj: Can existing buildings be upgraded to NZEBs? What will it cost to convert a regular existing building into an NZEB?

Yes, they can be upgraded. Large educational campuses or office complexes can be installed with retrofit installations that make a building move toward near zero energy. The cost depends on what you want to upgrade — your Central AC system; your current water or waste management process, Energy Efficiency of your network of lighting and pumps, vegetation at your campus and so on. What is important is that every single such intervention will pay back your entire investment in less than 5-7 years. Some of the investments offer a return of as much as 18-25 percent on your investments — specially on water and air-conditioning management.

Q from Dr Nagaraj: Does making a regular building and a NZEB mean a difference in cost of capital construction for a new building?

Yes, it will cost more. How much depends on what you seek to incorporate. Again this additional cost will be recovered in quick time. Besides, your capital cost on deposits for electricity will fall sharply if planned right with the right experts.

The challenge is for builders of homes who sell them, with the benefit of the savings going to the homeowners. So home builders understandably are hesitant to spend the extra capital cost, specially in a market where their earning margins are wafer-thin.

Q from Dr Nagaraj: Does a NZEB have more O&M challenges and greater operating cost than a regular building?

Quite the contrary. If designed and installed right, the cost of O&M and ease of managing the various elements of infrastructure relating to energy-water-waste-air is far higher. Into the future we expect even residential property developers will be encouraged by prospective home buyers to install such system at some small additional cost that reduces the homeowners’ cost of energy or water or of waste management.

At the time of writing this (April 2020) one new apartment of 1000 flats in Bangalore has saved the homeowners association about ₹3.5 crore a year with a near zero water management. A similar exercise is being steered by a team of experts at an even larger settlement of 2800 flats in north Bombay. To learn more, please mail us and we can discuss this offline. Every such investment in greening existing infrastructure offers a very attractive payback on the investment.

Q from Hamsa Varadan: A building becomes ‘net zero’ by using grid power at certain times of the day. Therefore, overall, the energy produced using coal etc., in the grid, doesn’t come down. Even if it does, it would be miniscule. Am I right?

Wrong. The net metering plan is now in practice in many ESCOMs. Please Check the web for more about it. It enables apartments, educational campuses, hospitals and hotels and buildings of any kind to use the external power grid yo ‘store’ power in the solar hours when your PV panels generate power, while you ‘draw’ it back in times of need for use. There are regulatory guidelines. Check them out on the web. Or get an expert who can help you with the process. The money that an expert will cost you will be a fraction of the smart savings the expert can bring. Please check with us. We’ll guide.

Q from Hamsa Varadan: Also, most of these exercises, seem to me, more to do with economics, rather than any love for the environment itself. Please comment.

Of course it is about economics. If you as a person have managed to live without power or water from the grid or without use of the net and all the conveniences of urban living then you can tell us how you managed it!

This is not about not consuming. This is about consuming sensibly and responsibly such that the overall pressure on demand for water or energy or the piles of waste houses like yours generate are reduced. Such reduction can be as much as 80-100 percent. That is what these ‘exercises’ are about. They surely reduce the footprint of consumption that you leave on the planet.

The very act of living is to be questioned then. The home you live in is part of such 'consuming', my friend. Can something be created without something being consumed or can something be consumed without something being created? That's the law of nature — one has to consume something in order to survive. It would have been beautiful if everything was absolutely self sufficient... If we can be aware of what is being consumed and how it is being consumed, it will make all the difference. It will make us more human. It’ll start a creative process of reducing the energy you consume. That is the essence of Near Zero Energy directions.

Q from Shakuntala Ghosh: This one is for Ashish and other HVAC engineers. To really cut down energy consumption in India, apart from other things we are doing, we HAVE to change the parameters of 'comfort condition'. In an Indian summer, 27 degrees with 75% RH is supremely comfortable. Why aren't we doing this?Then it will truly be an Indian rating system. Conversely, in winter (those places which have it), 20 degrees with 50% Relative Humidity is perfect. Like we have 6 climatic zones in India, we need 6 sets of comfort condition criteria. Would really appreciate some feedback on this. Want to adopt in my projects, but engineers are resisting...

This question has responses from four experts in the domain of air management. Kamal Meattle, Anil Dev, Ashish Rakheja and C N Raghavendra Rao

From Ashish Rakheja

Thermal comfort is a function of temperature, RH and air velocity. ASHRAE provides a chart wherein one can indoor choose comfort conditions based on several possible combinations of these parameters. The traditional thinking of low temperature & low air velocity model is now being challenged by designers. Many offices maintain 27 deg C, 60% RH and enhanced air velocity through HVLS (High-Volume Low-Speed) fans. They save significant energy in last 3 years and it makes for occupants a healthy work space. Over a period of time, the adaptive thermal comfort changes body physiology of occupants and they are uncomfortable at low temperatures.

The same holds good in winter. We can do low-temp, low-RH and low-air velocity. HVLS fans with large blades are now used in industries and airports and other places. The beauty of these fans is that they are soundless (being low speed) and produce air movement without draft. How much energy can a corporate office save just by changing the temperature setting? Can range from 3-5 % — but read what Anil Dev (CEO, Climaveneta, a Mitsubishi group enterprise).

Anil Dev adds from Bangalore :

Yes, a combo of 27 deg C with 75% RH will be extremely uncomfortable. Anything above 60% with 27 deg C is uncomfortable. As Ashish says, even 27 deg C + 60% RH needs to be accompanied with enhanced air movement. However, energy saving at 27 deg C + 60% rh compared to 24 deg C + 55% RH will be a good 8-9%! An option to large HVLS fans (which may be difficult in low floor-to-ceiling heights) can be multiple low speed fans that consume 10-15 watts or personal air circulation fans that consume just 4 to 5 Watts.

On HVLS further response from Kamal Meattle, Paharpur Business Centre, Delhi.

We need HVLS fans, cool roofs and cool sun-facing facades, pre-cooling of fresh air using a heat exchanger which is cooled by a Cooling Tower with a 1 degree reach and lots of plants to reduce the CO2 of the fresh air by 5-10%. This reduces the need for fresh air and for energy, Extend this to installing LED lighting, energy efficient motors and of course proper insulation and correct double or triple glazed windows, and you will have brought a complete solution. This is in addition to variable drives on most motors and pumps. In a 30 year old building we have been able to reduce energy use to 17 whr/m2/ hour, and with some more effort it can be brought down to around 14 whr/m2/hr - there is no magic and one has to have a will to get there.

Q from Neetu Jain: Is not ‘variable comfort’ same as ‘adaptive comfort’? And what’s your view on variable comfort criteria?

Anil Dev answers from Bangalore.

No, they are both different. There is an ideal or let us say most commonly acceptable thermal comfort level, at which most humans feel comfortable. Typically 24 deg C with 55% RH. At this temperature, most humans will feel comfortable. Those who do not, their situation is explained below under variable comfort.

‘Adaptive comfort’ means the thermal conditions to which the human body can adapt and still feel comfortable. For example, as an adolescent, during my engineering in Gujarat, I don’t remember feeling terribly uncomfortable at 41 deg C ambient, because we had no ACs at home! But today, I find this temperature very harsh as I have adapted to 24 deg C over the years. Yet, the human body can readapt. For example, if the temperature is raised from 24 to 27 deg C at the rate of 0.1 deg C per day, we will adapt to 27 deg C. We can take advantage of this and allow people to adapt to higher temperature and save energy.

‘Variable comfort’ is based on individual metabolic rate and also type of clothing and even to some extent adaptation to a different temperature. For example, you might be comfortable at 26 deg C and Gurmit at 22 deg C! This is variable comfort! To an extent, variable comfort can be countered by:

• Adaptation of some individuals to a mean temperature
• Making changes in wardrobe choices: someone who prefers a lower temperature can try switching to summer clothes (as Kamal Meattle suggested) and those who feel cold at the mean temperature could wear long sleeved shirts!