Thursday 27 September 2012

Author(s): Avikal Somvanshi

Green buildings: it’s common sense

Frenzied growth in real estate and changing lifestyle in Indian cities are inciting resource guzzling. Architects have innovative ideas to build green homes

Green buildings: it’s common sense

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  • Hello AVIKAL I have read

    Hello AVIKAL
    I have read your article, I would like to share my issue, basically I have a 4 rooms 15ft *18ft but all the rooms are covered by asbestoes sheets, and we have to face a lot heat in the room. kindly suggest what we should do

    Posted by: Anonymous | 3 months ago | Reply
  • Hi Avikal, Thanks for the

    Hi Avikal,
    Thanks for the valuable information you have given in the article and your answers here are to the mark a great help .

    I needed your advice here.
    We are building a school (NGO run) in Solapur district of maharasthra where the temp ranges from 43- 48 degres.
    The arch planning was done so that we had large ventilation winmdows with cross ventilations .

    We are planning to design the roof structure now and were thinking of the sheets like JSW and Tata blue scope but found out that this may a costlier and we donot have a budget for that .
    i was trying to exlore other options .
    your guidance in this area would be much appreciated.

    Rgds
    Milind

    Posted by: Anonymous | 4 months ago | Reply
  • Dear Mr.Avikal I am residing

    Dear Mr.Avikal

    I am residing in IV floor(Top floor) in my 4 storied apartment. Above me is the roof and it is entirely common passage. I would like to go for cool lime powder coating (two coats) for my top roof space(1000- 1100 sq.ft) and the quote was around 6000 to 8000. I feel i can reduce my power consumption by at least 1 to 20%. kindly your advice on this as it will be a useful idea or not and your advice will make me to go for it or not.

    Posted by: Anonymous | 5 months ago | Reply
  • Hi Avikal, I live in Punjab.

    Hi Avikal,

    I live in Punjab. We have extreme summers as well as extreme winters. Will putting white tiles on roof make cold interiors in winters?

    Posted by: Anonymous | 5 months ago | Reply
  • Hi Avikal, thanks for this

    Hi Avikal,
    thanks for this detailed article and also for the highly informative and sustained dialogue in the comments. We have a 'not-so-unique' problem, which we haven't been able to address, here in Delhi. For the last year or so, we have been renting a 1500 sqft shed with very old asbestos roofing, which is too weak to even step on. These being rented premises, we cannot modify/change the roofing itself. The space turns into an oven in the summers. We were advised to construct a false ceiling, so that we could use ACs in the summer. Is there any alternative to using ACs/ false ceilings? We have been making do with fans and coolers, but these are effective only to a certain extent.

    thanks

    Posted by: Anonymous | 6 months ago | Reply
  • Dear Avikal I have gone

    Dear Avikal

    I have gone through your communication with number of people having problem mainly the heat during summer, few are the residents at the top most floor of the multistory building.
    I am also having a similar problem here at Pune.
    I reside on 10th floor ( The top one ) and am experiencing inconvenience during current pre-summertime ( If I may say so )
    I wanted to try out a relatively cheaper solution e.g.
    Mix of Lime-Powder + Adhesive + white paint
    This paste to be brushed on roof top may be more than one layer to help radiate the heat.

    I would request you to kindly give a thought on it and revert back with your opinion.

    Posted by: Anonymous | 6 months ago | Reply
  • The cool roof that we used

    The cool roof that we used has become powdery and is spreading everywhere.We cant even walk on the terrace anymore without getting dusted with white powder or use that water for harvesting . in the regular cool roofing technique does this happen. how do we avoid the cool roof getting flaky and powdery. we don't want to tile the terrace as we may go for expansion in future. the green roofing is out of scope currently.

    Posted by: Anonymous | 6 months ago | Reply
  • Dear Narain, You are correct,

    Dear Narain,

    You are correct, first the terrace needs to be water proofed with the Seal and then the sloped with baby chips and final coat with rainguard. This will insure maximum protection from the rain. You can invest in thermal tiles but if cost is a factor than I suggest you opt for old or rejected bathroom tiles of whitish colour. You'll have to do some market search, usually companies dump huge scores of tiles because the develop minor defects and if you can get them nothing like it. As for reflective paint, I will not recommend it for terrace as it will wear-off very fast if you regularly use the terrace for recreational purposes. It will be very good for your western facade though.
    Very Best,
    Avikal

    Posted by: Avikal Somvanshi | 8 months ago | Reply
  • Dear George, I recommend you

    Dear George,

    I recommend you to invest in old/rejected bathroom tiles which are white in colour and get them laid on your terrace in form of mosaic by a skilled artisan. This will save you cost and will add to the charm of your terrace. This practice is very common in Gujarat and Mumbai, you can Google the details for this. As for your west-facing window, please refer my reply to the comment just above yours. Your problem is very similar to Suby's and solution will be the same, just make sure that while choosing the shading option (it has to be a mix of horizontal and vertical shading) make sure you get the right size which cut the evening sun completely.
    Very Best,
    Avikal

    Posted by: Avikal Somvanshi | 8 months ago | Reply
  • Dear George, I recommend you

    Dear George,

    I recommend you to invest in old/rejected bathroom tiles which are white in colour and get them laid on your terrace in form of mosaic by a skilled artisan. This will save you cost and will add to the charm of your terrace. This practice is very common in Gujarat and Mumbai, you can Google the details for this. As for your west-facing window, please refer my reply to the comment just above yours. Your problem is very similar to Suby's and solution will be the same, just make sure that while choosing the shading option (it has to be a mix of horizontal and vertical shading) make sure you get the right size which cut the evening sun completely.
    Very Best,
    Avikal

    Posted by: Avikal Somvanshi | 8 months ago | Reply
  • Dear Suby, You have rightly

    Dear Suby,

    You have rightly correlated your house's morning heating up problem with your east-facing window. Best thing to do will be to provide an external shade so that your east facing window doesn't get direct sun as this will best option to drastically cut down the heat ingress. You should invest in a sun-shade or an awning with vertical shade (something which will cover your window from three sides; top and sides). You can get it made by a carpenter or blacksmith or buy from some vendor. Additionally if you want you can reduce the size of the window and add a tinted film on the glass, it will improve your houses insulation factor but these are secondary.
    While choosing a shading option, just make sure that it is of right size, ideally it should be able to stop all the direct sun-light hitting your window in morning hours.
    Very Best,
    Avikal

    Posted by: Avikal Somvanshi | 8 months ago | Reply
  • I came across a product SIKA

    I came across a product SIKA rainguard and SIKA Seal. First the terrace needs to be water proofed with the Seal and then the sloped with baby chips and final coat with rainguard.

    Please advice for both my posts.

    Posted by: Anonymous | 8 months ago | Reply
  • My house is in Chennai the

    My house is in Chennai the house is west facing so expect more heat the house is 1000 sqft ground floor and first floor road facing there is bedroom. I had seen many thermal resistant roof tiles and see in many places the tiles have long cracks across the terrace. The tile price was around 40 Rupees and with labour comes to 60 rupees per sqft. My idea is to go with Thermal reflective paint for terrace and for the West facing bedroom and Hall to paint thermatek paint in the wall but i doubt will the thermatek paint on wall will last as normal Asian paint life of 4 years. The thermal reflective paint is 15 rupees sqft. As the house is only ground floor with only one room in the 1st floor have plan to build first floor in 4-5 years but who knows about future.

    For a west facing house in chennai is thermal tiles a need to survive the heat or reflective paint will be fine not sure if anyone use reflective paints in wall i have seen many used in terrace.


    Brands which one to choose : Thermatek/Reflectaa tile/paint, ABC tiles, Insulla tiles, Lune tiles

    Posted by: Anonymous | 8 months ago | Reply
  • Hi Avikal, Firstly thanks for

    Hi Avikal,
    Firstly thanks for an excellent article and discussion- it really does provide very useful information.
    Perhaps you could advice me on my situation. Our row house is being constructed (as part of a builders gated community) in Bangalore with a 900 sft roof terrace directly over the master bedroom and childrens bedroom. The terrace will also be in regular use as an entertainment area.
    The builders default tiles are a reddish brown tile, that are yet to be laid. In addition there is a huge west facing glass window in the master bedroom (the master bedroom is 600 sft and will need massive amounts of air conditioning that i wa/minimise.)
    I am willing to purchase my own tiles(preferably in the 30-40rs/sft range or can i treat over the already laid tiles?
    In case i do buy my own tiles can i use regular floor tiles or is there any choice between ceramic/vitrified etc.
    The heat resistant/reflective tiles are just expensive so arent an option.
    Thanks again for the article and your advice.
    regards
    George

    Posted by: Anonymous | 9 months ago | Reply
  • Hi Avikal I have a 16' x 8'

    Hi Avikal

    I have a 16' x 8' glass window facing east and also picks up a little bit of west .prob,em is that this room has only a small window and door on the opp side . In the day even in winter (I am in South india) the room gets heated up by 9am and cools only by 5 pm. I have two floors above and thus the heat is radiated by the large window. I am willing to reduce the view from the window by 75% since anyways this is covered by a curtain. I plan to fix 10 mm thick thermocole sheets on the glass (from inside the room) to cover 75% of the glass area.
    This is primarily to reduce the heat and power charges for running the ac.
    Will this treatment work or else can you suggest a cost effective solution. At present the window has sun control film and curtain with gaada cloth at the back.
    Need help to fix this problem early
    Thanks
    Suby

    Posted by: Anonymous | 9 months ago | Reply
  • Pl give few agencies or

    Pl give few agencies or individuals who do this job in Delhi

    Posted by: Anonymous | 10 months ago | Reply
  • I live on too floor in

    I live on too floor in .sector VII, Dwarka, New Delhi. i wish to have my roof properly done rpto avoid extreme summer months. Would you please suggest someone with his phone numbers who does this work. Kindly give three four references in Delhi.

    Posted by: Anonymous | 10 months ago | Reply
  • Dear Mr.Avikal I live in

    Dear Mr.Avikal
    I live in Chennai on the top floor of an apartment and the heat is unbearable!

    Some contractors are suggesting painting the terrace with materials like Insultec- is this a good idea? Or is it better to erect white roofing sheets on the rooftop? If yes, what kind of sheets?

    Highly appreciate your advice. Thanks.

    SB

    Posted by: Anonymous | one year ago | Reply
  • Please tell whether Thermatek

    Please tell whether Thermatek Heat Reflective tiles is the best.
    Or suggest any other brand that is reliable and cheaper.

    Posted by: Anonymous | one year ago | Reply
  • Dear Mr.Avikkal, Nice posts

    Dear Mr.Avikkal,
    Nice posts for cool roof. I live in chennai and experience the torture of 40* C. I am planning to build a house . I have found out that the cool roof tiles with white cement, dolomite, pp fibre and nano acrylate will serve best
    Vaidy

    Posted by: Anonymous | one year ago | Reply
  • Dear Hitesh, Cool roof or

    Dear Hitesh,

    Cool roof or painting the roof white might help reduce heat gain in your rooms by 3-5 degrees but to get a more effective and all season fix to heating/cooling problem, you should try insulating the roof. You can read about insulation here http://www.downtoearth.org.in/content/what-s-good-insulation

    Regards,
    Avikal

    Posted by: Avikal Somvanshi | one year ago | Reply
  • Hello Avikal I stay at the

    Hello Avikal

    I stay at the top floor of a two-floor house in Faridabad and like many others I am distressed due to extreme weather conditions in summers and winters.
    I read quite a few comments on this page but honestly I am confused which is the cheapest and best way to cover the roof. The end objective is that the temperature inside the top floor should be 6-7 degrees less than the outside temperature in the summers and should be 6-7 degrees more than the outside temperature in winters. So that the overall energy consumption to heat or cool the house goes down and it becomes more comfortable to stay inside the house.

    Kind Regards,
    Hitesh Batra.

    Could you please suggest which is the most optimum solution.

    Posted by: Anonymous | one year ago | Reply
  • we have done couple of

    we have done couple of experiments at our R&D building near TADA AP, a very hot place in Summer. An east facing SW development center with complete glass panels in R&D used to keep the AC ( 2.5 ton ) in 18 to 20 deg C during summer till 2012. Even then it used to be uncomfortable. We developed a thick wall of local creepers 5 feet away from the glass panels in 2012-13. From 2013 summer on wards till date the AC is being used at 26 deg C. For cross ventilation when required Remi Wall mounted DC fans ( 12V, 22W ) are being used which consumes no electricity or battery power, runs only on solar panels from 8 am to 5.00 pm. Also my own room facing the wrath of south sun and other engineers facing the west sun also had this problem. First we have put bamboo chicks on the outside ( 10 deg C temp benefit we got ) and now we are growing green cover also. I have't switched on my AC since two years as I have a nice USB fan and also DC fan with a container to hold ice cubes with tiny holes mounted firmly on the backside of the fan. Also I have built a 100 % eco friendly house at Sulurpeta near Sriharikota where I have done thermal, water, energy and waste management. Can post the article if interested. Ramkumar Senior VP R&D, ReGen Powertech

    Posted by: Anonymous | one year ago | Reply
  • Can i make whole shed roof

    Can i make whole shed roof with thermocol can it bear sun light . the aera is 5000 sq feet the sheets are fix on the steel frame . i have idea to use 3 inch thick sheet lenth of 8 *4 feet , give me right suggestion and the how long these sheets can work i have more then 9 month hot summer but rain is average 2 to 3 times a year

    Posted by: Anonymous | one year ago | Reply
  • You are doing good job. I

    You are doing good job. I have problem. I want to make cattle shed 500 Sq feet and i have idea to save cost because i cannot bear it. I have two ideas number one is to make Iron roof structure and bind 8*4 thermocol 3mm sheet to cover the whole roof .i face rain average two to three times in a year but temperature is almost 50 some time above 50 and also more then 9 month of long summer season Can it work under hot sun light for long time . the fixing problem i can solve to bind each sheet with frame at various points . waiting for kind suggestion.

    Posted by: Anonymous | one year ago | Reply
  • Avikal Somvanshi, My

    Avikal Somvanshi,

    My experiment went waste....can u delete my above post.

    The fact is I bought the thremocal sheet of 3mm..and Tried to stick it with a adhesive tape...but it did not with stand the air and it flew in the air ....so from that day till today ...their was no change in the temperature at all.

    My current problem is I am unable to stick the thermocal sheet to the roof-Floor...because of the dust and hot temperature the tape does not hold to the roof floor...

    What I have decided is to Stick the corners of the Thermocal sheet with adhesive tape and then put Fevicol on the Roof Floor and also on the adhesive tape part and then try to stick to the roof floor...

    so that Adhesive tape which is already STRONGLY binding/sticking to the thermocal it will also help me stick to the rooffloor much stronger...

    If u did not get what I explained here..let me know I will post few photos for you to understand what I am facing.

    Posted by: Anonymous | one year ago | Reply
  • Avikal Somvanshi, Hi Avikal,

    Avikal Somvanshi,

    Hi Avikal, Bangalore temperatures are touching 40 degrees...unbearable...chennai is still 35 degrees...
    Any how read all your above articles and I am so educated to beat the heat. Before I could read your article...I had ventured into purchasing 3 mm thermocol sheets and had insulated it on my roof top although it was hassle free now...going forward dont know what all issues I may face as we move to rainy days because water may start clogging...but I can remove the Celo-tape which I used to join these sheets and fold it and store it until next summer much effortlessly...

    My current problem is my roof top is 1000 sq ft and close to 900 sqft is exposed to hot sun for 10-12 hours...in my current experiment I have covered just 500 sqft of my roof top with thermocol (i.e just two bedrooms) sheets rest is still exposed to sun and I have not seen any reduce in temperature in thes bed rooms instead during aternoons the temperatures in these bedrooms have risen...and it is more suffocating compared to the other areas of my house... Is this because I have covered only half portion and the heat starts percolating to these covered interiors ?

    Also I had an Idea to fill some buckets of water under this thermocol so that it will reduce the temperatures and keep the interiors cool and as the water is under the thermocol it may not get evaporated too fast and weekly once 4-5 buckets of water should help me give the AC effect as the thermocoal also will hold the water from running away and going into the drain, pls share your knowledge in this regard.

    Posted by: Anonymous | 2 years ago | Reply
  • best cool terrace solutions

    best cool terrace solutions :

    1. Use a tin/asbestos shading roof on terrace.

    2. If you like stargazing & prefer a open roof, put a XPS board (Extruded polystyrene) layer on terrace and cover it with white coloured tiles or heat resistance tiles

    Low Budget ideas :
    3. Source some old bathroom ceramic tiles and put a layer on your terrace, paint them white with waterproof paint or heat reflective paints which are available plenty in market viz.. SURYA COOL,THERMATEK PAINT (google these keywords to get more details)

    4. Fix a shade net/tarpaulin which is commonly available in hardware stores its usually green coloured (http://www.kasturiagronet.com/), Fix the net/tarapaulin across the terrace walls with a gap of 5-10ft .









    Posted by: Anonymous | 2 years ago | Reply
  • Dear Omana, First thing to

    Dear Omana,

    First thing to start with will be painting the tin-shed white or in any other cool-colour which have high albedo. This should be readily available in any hardware store, I am assuming you are not harvesting rain from this roof, if you are then look for lead free toxic paints. This measure will drastically reduce the heat which the roof absorbs. To cut it further down, you can add some insulation in form of padding under the roof from inside. I suggest using grass or bamboo mats as padding, as these are organic and non-toxic. One inch thick layer will be enough. You can use lime plaster seal cover it in order to stop insects and rodents from taking home in it.
    Keep us updated on your little project. Do share your experiences and pictures for benefit of everyone.

    Thank you.

    Very Best,
    Avikal

    Posted by: Avikal Somvanshi | 2 years ago | Reply
  • Hello, I need some advice

    Hello,

    I need some advice regarding the roof top of my house that we are moving into. I stay in Guragaon and have this roof top wherein 300-400 fot area is covered in tin sheets, in hut type structure. I would like to know what kind of insulation can be done as this is also the area of indoor games for my three kids. Would appreciate a response.

    Posted by: Anonymous | 2 years ago | Reply
  • Found a product called

    Found a product called Thermatek. Do you have any feedback on this?
    Called them up and it sounds very costly though. Not sure how effective it is and how long will it last.

    Posted by: Anonymous | 2 years ago | Reply
  • 1cm spacing of cement(even if

    1cm spacing of cement(even if it is white cement) will turn dirty in few months.
    Another problem the 1 cm spacing with broken tiles will end up in having 10-20% of the total area being covered in cement exposed to Sun thereby reducing the effect of cool roof.
    And then of course I will have to buy good tiles and break them to make it, as I am unaware of a source of broken tiles here.
    Cost of installing broken tiles with 1 cm gap between pieces will also be higher.

    I have seen old buildings with roof covered with broken china pieces just the way you suggested, I am not sure of the source of materials and cost of laying it.

    I will keep looking for solutions.

    Posted by: Anonymous | 2 years ago | Reply
  • Dear Pinaki, You have some

    Dear Pinaki,

    You have some genuine concerns. Water seepage from the joints is a serious problem as the building ages, I would recommend that you use broken ceramic tiles to do mosaic work on your roof instead of laying the tiles in the regular formal fashion. Make sure the spacing between the tile pieces around one centimeter, and finishing coat is in white cement. This will drastically reduce any future seepage problem and will also take care of your heat trap concern.
    Do send me pictures of your roof once its done.

    Cheers,
    Avikal

    Posted by: Avikal Somvanshi | 2 years ago | Reply
  • An interesting article

    An interesting article indeed. I am building my own house and had come to the conclusion myself by googling on this over the last few months that white ceramic tiles would be the best solution for cooling the roof, with the next best solution being white paint. The two issues that bugs me regarding ceramic tiles are:

    1) Whether the joints between the tiles will crack/come off over time due to heat and UV exposure leading to water seepage.

    2) Ceramic being a poor conductor of heat, the tiles will also trap the heat well, thus not letting the heat escape during night.

    I live in Kolkata.

    Posted by: Anonymous | 2 years ago | Reply
  • Dear Saxena ji, Thank you for

    Dear Saxena ji,

    Thank you for inquiry.

    West facing windows can be a big source of heat, first measure which you can explore is to add a chhajja (sun shade) on the window if you don't have one already. West sun will also require some vertical shading device too. Explore options of having vertical fins on the side of the windows.

    Your second question regarding roof insulation using thermacol. Thermocol can be used, but it will absolutely need a good protection. This protection is generally a layer of 3''-thick PCC (plain concrete) with joints every 6 feet, and that entails using a very strong, high-density thermocal, capable of supporting permanently the load of the PCC. Ordinary thermocal won't do. Then this PCC can be covered with white tiles. It's a relatively advanced solution, which addresses both roof insulation and cool roof. It is best if you can do this.

    Regards,
    Avikal

    Posted by: Avikal Somvanshi | 2 years ago | Reply
  • I live in a flat on the 8th

    I live in a flat on the 8th floor which is also the top floor/ I have three windows facing west. I want to reduce the heat from the roof top. Although nobody walks on the roof but I am not very clear whether thermocol will withstand the pressure if somebody walks on it even if it is covered with white tiles. Please suggest the best option.

    Posted by: Anonymous | 2 years ago | Reply
  • In 70s itself I designed a

    In 70s itself I designed a cooling system. Usually in South India people use mud pots for water storage. These mud pots have a cover(concave shaped). It has about 1foot diameter and i cm thickness. When inverted it will have convex shape. On a flat roof these CLAY COVERS will be arranged side by side with gaps filled with mud. These are white washed(calcium coated). One gets on an average 5 degrees Celsius drop from ambient temperature. The principle is white colour reflects then the sunrays have to pass through mud and air trapped between clay cover and roof. Still air acts as INSULATOR. These clay covers can be made locally.

    Yet another method is to spread a polythene sheet on the roof and covering with thin layer of soil. One can grow fast growing plants like Coriander seeds and mustard seed. these plants germinate quickly and the roots spread horizontally. One can spray water. This way the temperature inside the building will come down drastically. After the Summer season, the polythene sheet can be rolled back.
    Dr.A.Jagadeesh Nellore(AP),India

    Posted by: Anonymous | 2 years ago | Reply
  • Dear

    Dear MySchizoBuddy,

    Old/broken white bathroom tiles over any synthetic paint anytime. Tiles will be both more durable and non-toxic. And as for your second question, you need insulation for sure in your roof, cool roof will add to that. Just cool roof wont be as effective. So go for both.

    Cheers,

    Avikal

    Posted by: Avikal Somvanshi | 3 years ago | Reply
  • Another question regarding

    Another question regarding residential roofs. Should i just opt for a cool roof made of white ceramic tiles and forget about the thermocol in the roof itself or should i do both of them.

    Posted by: Anonymous | 3 years ago | Reply
  • Will white reflective

    Will white reflective bathroom tiles perform better than white glossy paint that is used to paint metal structures?

    Posted by: Anonymous | 3 years ago | Reply
  • Many thanks Avikal, will go

    Many thanks Avikal, will go thru mnre website along with BMC guidelines also .

    Posted by: Anonymous | 3 years ago | Reply
  • Hi Viren, You don't need any

    Hi Viren,

    You don't need any kind of special permission from BMC to install solar water heating panels on your roof top. In fact you can avail government subsidy or soft loan for these under Jawaharlal Nehru National Solar Mission (JNNSM) of the Ministry of New and Renewable Energy (MNRE). You may also refer to MNRE official website at ÔÇ£www.mnre.gov.inÔÇØ for more details.

    As for cool roof benefits, they will be limited. I'm assuming your panels wont completely cover the whole of your roof top, thus portions of it wont be shaded from the sun. This will lead to heating up of the roof. My advice would be to apply one of the cooling techniques mentioned in the article for the portions of your roof which wont be shaded by the solar heater panels. This should improve your buildings performance.

    Thank you.

    Regards,
    Avikal

    Posted by: Avikal Somvanshi | 3 years ago | Reply
  • We are planning to make fix

    We are planning to make fix solar water heating panel as a canopy on our terrace.

    Besides the cost benefit of having hot water , there will also be benefit of having heat reflected from the terrace surface.

    Does one need any special permission from BMC to install these panels over roof top in Mumbai city?

    Posted by: Anonymous | 3 years ago | Reply
  • Dear Mallikarjun

    Dear Mallikarjun Nalluri

    Heartening to read about your experiment with roof insulation, it is sad you felt lost at the end of it. What I can figure out by your description of the 2 experiments is that they were very short duration, and you gave up too soon. Let me explain.

    The first one with thermacol sheets was flawed to start with. Putting insulation under the roof is wrong practice for hot climate like ours, as this allows the roof to get heated by the sun and transfers it via other elements in building like you observed (walls and pillars). Under the roof works for cold climate where there is a need to keep the heat inside. In hot climate it should be on the top of the roof stopping it from gaining heat. Like your second experiment did by creating a water pool on your roof. And it is strange that you could not feel the difference in the thermal performance of your office space. One of the reasons for this has to be that your office is completely air conditioned, thus you and your staff might not have experienced dropping of temperature. Second reason for this is your quantification of saving via monitoring power consumption. There wonÔÇÖt be any power saving if you continue using air-conditioning at same settings as before. Advantage of have a well insulated roof is that it brings down the room temperature by 2-5 degree centigrade, allowing the thermostat of the AC to be set at higher temperature around 24-26 degree centigrade. If you didnÔÇÖt do that your power meter wonÔÇÖt register any change. And in longer run this also translates to lesser use of AC as there will be more days in the year when thermal conditions will be naturally pleasant. You should give these passive measures more time to kick in, over a day difference do happen but then your building should have been un-condition to really feel the change.

    Permanent water pool on roof is not best of the option, as it is very water and resource intensive as you will have to regularly replace the evaporated water. Additionally there may be water seepage problems. Like discussed in the article a white wash or a vegetative garden will offer more durable solution.

    Keep me posted about your experiments, and keep experimenting. Who knows you may discover something even better.

    Thank you.

    Regards,
    Avikal

    Posted by: Avikal Somvanshi | 3 years ago | Reply
  • I have done an experiment at

    I have done an experiment at our organization(on 12,13 March 2013).
    We have a 2 floor building in vijayawada(A.P), the roof is openly exposed to solar radiation. To protect from the heat being conducted(as our office is airconditioned), we have insulated the roof from the bottom with thermacoal sheets. Still my assumption was that, heat may be getting transfered through pillars and walls(as pillars/walls are in contact with roof). For this to understand, I have filled up the roof with water(all through the day) and observed if there was any reduction in power consumption. But there was no reduction in power consumption. I have repeated the expt, but still no decrease in power consumption was observed.....so finally i concluded that, power saving by stoping radiation will not work in our organization....
    Please let me know your feedback on this...

    Posted by: Anonymous | 3 years ago | Reply
  • Black body is a good absorber

    Black body is a good absorber of the radiant heat and is a good emitter too.
    White bodies are different from this.
    Now a days,one can get white coloured cement paints in the market ,that can seal minute cracks and pores as well as it gives this added effect in thermal properties also.
    One can have two birds in one shot too.
    I have tried recently.
    It is effective.
    Why not you too ?

    Posted by: Anonymous | 3 years ago | Reply
  •  Dear Tautik, Thank you for

     Dear Tautik,


    Thank you for your kind words. Yes a smooth white coat will be effective to reduce the heat gain. While choosing the paint check for that the paint is free of lead and Volatile Organic Compounds (VOC). Normally these are mention on the product itself. Lime wash will be an excellent option as its both non toxic and light on pocket. Only issue with lime wash is that you will have to redo it annually after every monsoon. If that is fine with you, I'll recommend lime wash over commercial paints (they will last for 3-4 years). If you are looking for a more permanent solution, laying white bathroom tiles or a terrazzo work with broken white tiles or chips on your roof is most recommended. Be free to ask any other queries if you have, I will be happy to answer.


    Regards,


    Avikal



     

    Posted by: Avikal Somvanshi | 3 years ago | Reply
  •  Dear Rohit, Good to know you

     Dear Rohit,


    Good to know you are already thinking about cool roofs, honestly it is all common sense and most architects are well aware of it. As for the atrium of malls and similar structures, yes, applying cool roof technology will surely bring down the cooling energy need. But painting the sheeting covering of the atrium skylight won't be a very wise step as it will cut off the natural light from it. I'll recommend using sheets which are of inherently reflective material or cover the skylight with vinyl-coated polyester mesh fabric or similar products. Tata Bluescope roofing sheets which are colour coated are good option compared to a dark roof. Any metal roof with lighter colour coating shall reduce the heat gain but they normally need to be coupled with some kind of insulation underneath to cut down the heat transfer due to their high thermal emissivity and low thermal mass. Tata Bluescope website claims some high end sheets to be of lower thermal mass and higher heat reflectivity, but they do not give any numbers regarding SRI, which is the real indicator of roofs' cooling ability, so I am a bit sceptical about their actual performance. You can read more about SRI and roof cooling options at www.coolrooftoolkit.org


    Regards,


    Avikal

    Posted by: Avikal Somvanshi | 3 years ago | Reply
  • Dear Madhav, I am glad that

    Dear Madhav,


    I am glad that the article added to your knowledge base. As for 30 degree Celsius temperature difference, the point to be noted is that Khatri is referring to the temperature of the roof surface, not that of the air; and here in Delhi, temperature of the roof surface can shoot up to 90 degrees Celsius in peak summer. The reduction which Khatri claims is on the higher side but it is not magical. Scientific studies by LBNL and IIIT-H have recorded 15-20 degree Celsius on average by converting a black roof to white roof in Hyderabad. Reflective coatings used in ITC-Gurgaon building are of way higher SRI value then used in the said studies, which sort of support Khatri's claim and I have just quoted him (haven't personally verified his claim). You can read about these studies online. Green or cool roof is your personal choice and project need, I will be happy if you are using anything except dark uncool roof, do refer to white v green roof box on the option section.


    Regards,


    Avikal

    Posted by: Avikal Somvanshi | 3 years ago | Reply
  • Dear Avikal Impressed by the

    Dear Avikal

    Impressed by the simple solutions of creating a cool roof.

    For a 20 year old concrete roof in Kolkata, would 'smooth coating' make sense (if i understood the 'options' correctly). Does it mean painting the roof white with a commercially available white exterior paint. Is there a non-toxic paint available? Would lime-wash suffice?

    Too many queries...

    Posted by: Anonymous | 3 years ago | Reply
  • Hey...As per me, not only in

    Hey...As per me, not only in Delhi, but even in case of Ahmedabad the problem is similar--people prefer to avoid buying property on top floor, considering the amount of heat the slabs transmit to the flat below, converting it into an oven. In general, I would prefer to replace the top most slab with filler slab technology to create a buffer and minimise the temperature inside the room. Also, on the top of that I will suggest to create mosaic of white reflective ceramic tiles, which as Manu Gopalan said, would not be toxic and would be a permanent solution for the cause; plus it adds to the waterproofing requirements. Recycling of reflective tiles out of their broken pieces, easily available with tile manufacturing companies, is cost efficient, too. In corporate offices where AC consumes much of energy during day time, it will work for sure and also in residential buildings. Iin this write up, u mentioned about commercial buildings; so for instance, if say there is a mall, then on the large atrium of the malls, would painting the sheets covering them minimise the heat below? Or will these TATA coated sheets available  act similarly???  Ar.Rohit Tak Pune

    Posted by: Anonymous | 3 years ago | Reply
  • Definitely an appreciable

    Definitely an appreciable cool idea which never struck my mind before. It's vernacular and easy to implement. 30 degrees Celsius difference in temperature is magical, admirable, although an  unacceptable figure. I will personally favour the idea of vegetation on roof which can act as a replacement to the vegetation harmed by the concrete structure. This cool idea can be extended to the walls.

    Posted by: Anonymous | 3 years ago | Reply
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