 So, good afternoon to all of you. In the next 25 minutes, I have been given the task to talk about renewable energy options for buildings. So, you had already a series of lectures focusing on green buildings, focusing on passive and so I am going to touch upon the active renewable energy options. So, the way we plan it, let's start with a set of questions. The first question, these are the questions that we are going to answer in this talk is, how much energy do we use in our house and we will try and do a simple quantification so that we can, so each of us, all of us live in house and so if we want to see how much energy we use, we can do this and this is a simple number to calculate. Then we look at what is the end-use pattern for the building, then we ask the question why opt for renewable energy at all and then list out the different options and then close with some examples and then challenges for renewable energy systems in buildings. So, before we look at it, when you look at from an energy systems point of view, we need to look at the energy that is available in nature which is primary energy and this could be your solar, it could be wind, but it could also be fossil fuels, it could be coal, oil, natural gas and that goes through a series of sequence of steps and through energy conversion facilities to give you a secondary energy which is refined oil or electricity goes through transmission distribution system and then you get the final energy that you pay for. The final energy that we pay for normally for our house will be maybe electricity and LPG and then that goes to our equipment and then then you get the useful energy and the end-use activity. So, we may do when we do the calculation, we can do the calculation at the point of the energy service which is what we are interested in that is we want comfort conditions, we want heating, we want cooling, we want some motive power, we want illumination and in order to do that we are buying energy which is final energy or we are using some energy from nature which is the primary energy. So, at any of these levels either the energy service or the final energy or the primary energy. So, we will calculate the final energy and the primary energy for a typically for a house and so let us look at this, how would you calculate it? Let us say we have your each house is paying an electricity bill. So, take your electricity bill, I have taken a simple example of a house which does not have air conditioning and say we are using 120 kilowatt hour per month and depending on the number of people you have in the house and the amount of times that you do cooking. So, you will have a certain amount of LPG users, I am just assume let us say 1 cylinder per month is a reasonable assumption for a small family and if you look at this we can then take this and convert the numbers take that 120 kilowatt hour and then you convert it into kilo joules and divided by 1000 to get mega joules. So, you get 432 mega joules per month, if you look at LPG 1 cylinder has 14.2 kgs and so, multiply that by the energy content of LPG and you get another about 600 mega joules and so, if you add these two up you get essentially the energy use in your house and you can just plug in your own numbers and this is now the energy that you use the final energy that you are getting. If you want to convert it in terms of primary energy remember that the electricity that you are using has already been has already taken much more in terms of primary energy because you have a coal power plant facility and that has an efficiency. So, we take this 432 divided by an approximate number of 30 percent LPG also has some refining and you know from crude oil if you are getting it, but that efficiency is about 90 percent. So, if you add it up it comes to about 2100 mega joules per month. So, you can immediately do the simple calculation similar calculation for your own house and then depending on. So, if I look at that multiply it and you get so many giga joules 25 giga joules per year suppose it is a 4 you know we have 4 people divided by number of people and this gives you immediately 6.3 giga joules per capita per year. We will just keep tab of this number because I want to compare this number with what are the numbers for other cities in the world. We can also look at what we are interested in in all of this is we are may be interested in energy, but we are interested in the price that we pay for the energy. So, typically you will be if you are talking 120 kilowatt hour we are in the slab 100 to 300 kilowatt hour the way most of our electricity is priced is we have a slab system if you use more per month and you are in a higher slab the price of electricity is higher. So, 100 to 300 kilowatt hour roughly about 5 rupees per kilowatt hour multiply that. So, that means we are getting about 7000 rupees per year is what we are paying on electricity and for LPG we are paying about 5400 rupees this is subsidized. So, if you take it unsubsidized it is about 10800. So, for energy for this house that we talk of we are paying 12600 rupees per year as compared to and if it was unsubsidized 18000 rupees. We will look at this this number is to be kept in mind because when I am going to talk to you about renewables we will see the same numbers for renewables. So, that you can get a sense we cannot talk about energy without talking about emissions in today's world every time we could look at. So, you can immediately look at this multiply the electricity by an emission factor depends on what kind of how you generate your electricity. So, if it is more of coal then the emission factor will be higher if it is more hydro it will be lower. So, for an average for the Indian context it is about 0.9, 0.89 kgs and LPG is about 65 kgs you can multiply this and you immediately straight away get what is the amount of kg of CO2 per year and per person and this is something that you can easily do for yourself and you can see for your house for your electricity and cooking this is the amount of energy this is the cost and this is the CO2 and then we can do the similar calculation for the other renewables that we talk about later. So, if you look at this is from a global energy assessment and you will see that the giga joules per capita for different countries for residential uses and you will see that this red part a large part of these are cold countries and a large part of the energy which is used is basically for space heating and if you subtract if you remove that and you look at the remaining part of it then you see that we are somewhere over here when we talked of that 6.3 giga joules per capita, but these are different kinds of numbers. So, let us move on and let us look at in the Indian context as a study in Delhi and you can see the end use electricity by different appliances. So, you see that you know we are looking at cooking and lighting and also there are other you know the television refrigerators air conditioning and then there will be a different mix for summer and winter. So, we need to understand these kind of appliance ownership different countries also have different supply mixes. So, if you look at India for instance it is not it is something which you may surprise you or today are building energy use is predominantly renewables and however, this is because it is predominantly for cooking predominantly cooking by biomass traditional renewables very low efficiency. So, if you look at primary energy supply as people move up the energy chain and you go for more and more convenient fuels this is going to get shifted this biomass section is going to get shifted into kerosene or LPG or electricity and. So, if you look at the mix of other countries you will see that heating and electricity and natural gas etcetera all come in. So, this is just so when we talk about the present situation for electricity and power generation we are mainly thinking in terms of large centralized generation which is going to supply you electricity through a grid when we talk of future possibilities we are also looking at each building having its own generation. We are thinking in terms of cogeneration tri generation decentralized distributed generation and demand side management. So, this is something that you have to keep in mind it is not necessarily only the context that we have. So, if we now talk about that building which has 120 kilowatt hour per month use I have put down based on that study there is a world bank report which has a study of appliances and for those appliances with the ratings we have built up for each of these appliances and end use curve and the total load profile as you can see the load is not constant and you have to meet the peak most of the peak is basically in the evening and night time. So, for this building we have this requirement is about 0.4 kilowatt peak and on an average we are requiring for this house it is a non air conditioned house remember we are talking of 0.16 about 160 watt is the average through the day and keep these numbers in mind because I am going to now design we will look at a PV design for the same kind of building. So, before we do that let us now look at what is the what are the motivations why should we opt for renewable energy. One motivation fossil fuel prices are increasing and most of the places in India we have energy shortages we have electricity shortages you all know that the US dollar is way you know we started with 45 and now it is like 64. So, energy security when you look at the amount of money we are using to pay for our oil bill energy security means that if we can have control over the energy that we are using and we can have an uninterrupted supply which means that we again renewables offers you that option. The most predominant driver today is greenhouse gas emissions global warming and climate change. So, even if we have fossil fuels the overall CO2 emissions that are caused by fossil fuels implies that we cannot continue to have our future energy systems only be fossil fuel based also there have been and are continuing to we are continuing to have significant improvements in renewable energy costs are decreasing there is a very steep learning curve and we anticipate and expect that renewables are going to increasingly become more and more cost effective. So, that is these are the reasons why we should be looking in for renewable energy now there are variety of renewable energy options and we will touch upon a few of them because currently based on present technology these are the ones which are likely to be suitable for buildings. So, we look at solar we look at solar thermal solar photovoltaic we look at wind we can have ocean thermal energy for large scale centralized we look at some biomass geothermal small hydro wave energy and tidal and of these in the context of buildings the ones that are short list for the options are solar we can go for solar and solar photovoltaic for generating electricity solar thermal for space heating and for cooking and water heating we will look at biomass could be used for water heating could be used for space heating, but biomass predominantly we will look at for cooking wind could be for electricity again electricity then could be used for all electricity also appliances geothermal cost effective solution in many cases for space heating and space cooling and of course this is not an exhaustive list you can think of various others, but these are in today's technology in my opinion these are the ones which are most near cost effectiveness. So, let us start with solar and solar photovoltaics and these are some pictures taken from the web of solar PV modules and I am sure many most of you have seen some of these and you have different kinds of products for instance lighting products these are of course using CFLs and now you have solar lanterns using the LEDs and you can have solar home systems and solar power supplies and this is a installation for instance a 5 kilowatt peak installation at a small village on the way from Mumbai to Pune at Rajmachi village it is a 5 kilowatt peak solar system. This is a picture of a passive house with zero energy building and you can see the solar PV modules on the side let me go through these and these are some schematics of how you can connect your grid connected systems and there are several such things if you can just look at these systems and many of these systems are functional this is one of the you can see the PV integrated into a building it is the CII building at Hyderabad. So, and different concepts and you can look at the European Union and you have different kinds of images of building integrated photovoltaics which are there at IISC Bangalore where they have a BIPV lab and they put a panel of about 5 kilowatt peak and they have got this paper report some of the results that you have from this BIPV. So, this is actually integrated along in with the roof and this is the glass panel which we are looking at and you can see this is the schematic of that structure you can of course, see that the output of this varies over the year and you have a DC output and then in the AC there is a conversion loss efficiency and this details are there in the paper in the reference. So, one of the challenges that we have is the solar insulation the supply is not constant and typically over the day when you see this is the time when you have the requirement where you have the supply the load that we had we saw that that has a different kind of requirement. So, then unless you have a grid connect if you are going to have an isolated system then you are thinking in terms of batteries and storage which is again costly and. So, that is the and of course also there is a seasonal variation. So, for instance if you look at Mumbai you can see that different months during the monsoon months the solar insulation is a little less than the other months. So, now let us look at that same installation that we talked of 120 kilowatt hour per month and we want to design for that system let us see what are the panels that we can choose. So, I have chosen a panel which is a BP 3125 panel and this is the current versus voltage curve for this a peak rating is 125 watts. So, we choose 10 of these panels and that would be if you look at the energy under the area under the curve along with the battery and the some efficiencies assumed that is enough for meeting the requirement that we had shown. We also take a battery let us say battery of 4 kilowatt hour and for this system then this is my solar generation. If you can see this this is the solar generation of course the peak of the solar generation as I said was 1.2 kilowatt peak rating and of course this is for a particular insulation. So, the kilowatt rating is little less and then for that this is the load and then you have some of sometimes the load will be come from coming from the battery you have a battery charging and battery discharging and you can take this from me, but you can cross check it you can take this area under the curve is equal to this area. So, now let us look at when you do this approximately with the numbers that you can have this system is going to cost the PV modules will cost about 70,000 rupees battery will cost depending on the rating 25 to 30,000 I have taken 30,000 and the balance of system and the inverters controllers are the 30,000. So, we are talking of a total approximate cost of 1.3 lakhs and the annual savings of about 7200 and that is the reason why all of us do not have PV powering our homes. However, many parts of the world and even India is proposing that that we all often we induce because we have a preferential tariff. So, even if you just look at this and you think in terms of a preferential tariff of 15 rupees per kilowatt on the many parts of the world the tariff for a PV based electricity is even higher than this. So, even if you just look at that and you say that we have grid buy back and net metering grid buy back and net metering means that I can take from the grid whenever I want and I can supply back to the grid whenever I want and the advantage then is I do I can get rid of my battery. So, that will reduce your cost and now your cost is only about a lack and now your saving annual saving is about 21600 with a 15 rupees per kilowatt. So, the payback period is 4 to 5 years which is which is reasonable and. So, if you have the right kind of conditions even now it is at the margin and then if you look at some of the malls or some of the other places where your electricity price is even higher then and PV costs are going down. So, in future you can think in terms of looking at some of these things. The other technology currently which I mean many of you are from Bangalore or from Pune you will see almost everywhere there are solar water heaters and this is something where we are looking at most of the water requirements that we have are at relatively low temperatures. So, even flat plate or evacuated tube collectors you will you will see that it pays back for itself if you are replacing electricity for in about 3 years or so at today's prices. So, even without any subsidies this is something that is viable and this can be used solar cooking something which is potentially possible, but not the problem is that we need to then change our cooking habits. So, flat plate sun box cookers, but the problem is then you will not be able to do deep frying and several of the other things that you could not be able to do. On the other hand if you have concentration for instance you have the shaeffler and then you concentrate it then you will see incidentally this image of the kitchen this is actually a solar kitchen. So, there is no flame there and so this can enable wide variety of cooking and the problem is this is Ajay Chandrak's innovation where he actually even in a household with a balcony you can just put this concentrator there and you can have a pressure cooker putting that. So, there are this is today is based on this this kind of cooking can be a supplementary cooking. However, for institutions and community kitchens you can look at concentration and steam and you can have steam based cooking and that could be almost like a viable option. The other option is when we look at biomass and we are talking of biomass gasifiers we need to look at getting more convenient and LPG kind of quality of flame and for that we have a number of designs of biomass micro gasifiers and biomass gasifier cook stoves and so and these typically will cost you of course will cost you initially 2000 to 4000 rupees and there have been different kinds of schemes and you can see the flames which we are talking of these flames are as good in terms of the density we are talking of efficiencies of conversion of the order of 50 percent and LPG is about 60 65 percent. So, this is technically these are possible some of these are commercial for instance this is a design which was ISC was involved and BP and there is a company which is now looking at it URJA this has a fan in it and they are also looking at here a fuel chain where you take biomass and you pelletize and these biomass pellets this will come to about one-fifth the cost of your LPG and there is a small initial model had lead acid battery now there is a nickel cadmium battery which is used in these. There is another interesting it is a award winning innovation it is a bio lights stove and the idea in this is that the flue gases the products of combustion which are here you have a thermoelectric generator and that drives the fan that also provides for you an option where you can have an LED light or you can charge your mobile phone and in terms of cost still they are talking of something of the order of about 70 dollars price, but there are ways in which so you can see this is an active area and this is something which can also be thought of and near our home in the in Pune there is a association called ARTI appropriate rural technology institute and they have this biomass gasifier stove they also have you know when you look at vegetable kitchen waste you can use that kitchen waste to give you a bio gas and you can run that and so you have two digestors one is possibly on a rooftop and one could be actually even on there was small unit which can even be put on a small balcony and these are this is another option which is there and geothermal of course we can look at just the ground heat pump or heat cooling, but there are also places where you can use the heat which is available for cooking and so this is these are the this is basically the geothermal map of the Indian context and we can think in terms of integration of the geothermal with building integrated PV and so you can look at building integrated PV and then heat recovery and then ducting and system of light so geothermal heat pump typically very common in many of the European US countries we are talking of small delta T's so you can use the ground as a source of heat and in the Indian context you can use the ground as a source of putting in in your air conditioning system instead of having the condenser you can put that back into the ground and then your overall efficiencies will improve and now there are some companies were in this space. In the case of wind Professor Swathi talked about that large building with wind machines you can have also small wind machines and this is the Auroville's wind generator 2 kilowatt peak rating and it can be put adjacent to the building and then you can have the interesting thing is wind and solar the resources are actually complementary so normally when you have high wind you have low sun and low sun high so there is if you combine wind and PV then the overall ratings will be so there's a synergy in that and currently if you want to do this you know you want to have a 5 kilowatt or a 10 kilowatt hybrid system the government gives you quite a bit of subsidies so you can get actually a 10 kilowatt system for about 2.5 lakhs or so and I think about 70 percent is subsidized and it's another option okay so I've come to the closing of this lecture I have given you a quick overview of the different kinds of renewable energy options that are possible for buildings what are the challenges and what does the future hold in store for us we have there's significant scope for technology development in all of this technology development and cost reduction when you do renewables in building the first few things that you have to do is integrate the demand side management first see that can you reduce your loads so whether it is by passive or it is by more efficient systems reduce your loads look at efficiency demand side management and then passive then configure the active systems for your and then the main challenge here is to match your supply and demand and storage is right now costly so cost effective storage is going to be another challenge for the future there is an issue of decentralized and centralization overall our grades are energy supply systems our society is all gone towards the centralized kind of model many of the things that we are looking at for buildings imply a decentralized model and we may even go back to DC right now all our appliances are AC so we take that PV the calculation that I talked of PV then take it to an inverter then get it to AC and then have the devices running on AC but we can think in terms of having a DC grid in the interim there will be hybridization so you will going to have renewables and fossil and then you have to have controls we are talking of smart metering micro grids all of this the cost angle will come in we can redesign the houses for renewables and this is a challenge for all the architecture people because you can rethink the way you design your house so that you integrate renewables into it and finally the whole thing is future systems are not going to look like what exists today so there is scope for R and D and innovation and of course there has to be policy support to sort of make this happen I just want to acknowledge some people who helped me in preparing this presentation end with a just quotation from an American philosopher writer poet Henry David Thoreau who said what is the use of a house if you haven't got a tolerable planet to put it on so what we need to think of when we look at renewables is how do we make the houses that facilitate a tolerable planet okay and so there are a number of references I've tried to go through several things but I've quickly gone over it and you can go get a lot of details from these two pages of references okay thank you all