Friday 10 May 2013

Passive Cooling

This week, I travelled to Dehradun, I saw a lot of houses using innovative techniques to design a Naturally Cooled House, and one of them included a house near the Rama Krishna Mission.  It was a regular house and used solar water heating for its winter requirements.  During the summers, which of course, in Dehradun are cool as ever the same solar water heating was used to heat up water during the night.  The house belonged to a Mrs and Mr Ashwani, she is an IIT Delhi Engineer and has done a lot of research in farming techniques, using the innovation that he had learned and un learned in IIT to develop farmlands.  His house used something called as Passive Cooling to cool up the house, this included Natural Ventilation, Thermal Cooling and Evaporative Cooling.

The concepts became clearer as you looked at the house, and I have seen a [few structures] for myself, it utilised the natural methods of cooling, for instance using the [natural air flowing] through the house, the water evaporating from springs near the house and the stone and earth used to absorb and cool down the house.  All these methods are called passive
cooling and unlike mechanical cooling is natural and involves changes in the design and careful architecture.  The idea behind passive cooling is to understand what factors actually generate coolness in the house, and they are as listed below :

1.  Monitor the average minimum temperature.
2.  Monitor the average relative minimum humidity.
3.  Monitor the average maximum temperature.
4.  Monitor the average relative maximum humidity.

Ideally in the summer, in this nation when the temperature in most places touches 45 deg C, the relative humidity is very low, so the combined affect is to raise the temperature even further, scorching all vegetation and destroying human forms, the heat wave deaths are not unknown and largely touch up to 1000 every summer in the Delhi NCR region.  The government has looked at various bylaws to reduce this toll, which have culminated in the building of shelters, however it is to no affect, as they ignore the largely salient parts of the environment which takes care of itself naturally.

The ideal thing to do before you decide on a strategy for the same is to plot a chart vis-a-vis the relative humidity and temperatures be it maximum or minimum.  Then the strategy to implement a passive cooling system can be found out.  So basically, there are mainly 4 methods of passive cooling identified below :

1.  High Thermal Mass with Night Ventilation.
2.  Evaporative Cooling.
3.  High Thermal Mass.
4.  Natural Vegetation.

Based on the chart as I have decided to make I will go ahead and implement the following strategies, this is a very interesting piece of information that I came across while I was
reading an old article which says that "Passive Cooling gets rid of heat during the day and cools down the temperature during the night".  If we were all made aware of how much reduction of mechanical cooling can reduce harm to the environment it would truly make some remarkable progress in the Climate Parliament.  These techniques have been developed over ages and employed by our ancestors when the air conditioning did not exist.  To the best of the knowledge of the experts I know, you would want to reduce the heat gain in the first place with high insulation levels, heat blocking windows, proper solar orientation and good vegetation and greenery around the house.
Oh Lord' , Cooling of any kind helps, especially that you give to me. 

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