Let the earth beneath our feet give us free heating & cooling

Posted by Kate McMahon at 7:16 am

Preliminary plan showing possible location of underground pipes in our neighbourhood

Earth (or labyrinth) heating and cooling is one of the oldest climate control systems in existence. The ancient Athenians used it, as did lots of old buildings that were built before the invention of air conditioning (like Melbourne’s Parliament Building). And of course, there's a massive contemporary labyrinth cooling system under Federation Square (shown on the right).

The idea is that you make use of the fact the underground temperatures are fairly consistent all year round (fluctuating less than 10˚C) by building a series of underground pipes which carry air under the surface to be warmed or cooled.

In summer fresh night air is taken into the underground labyrinth and cooled to earth temperature, controllable vents allow the air into surrounding buildings at floor level, and warm air is released through high vents.

In winter the process is reversed, and cool air in your house is replaced by warm air.

Very little energy is used as electric pumps are only needed to boost the natural convention system when required.

In summer the system might work well enough not to require any additional air conditioning (at least not for most of the houses in this neighbourhood), in winter conventional heating systems would probably have to top up the 'free' warmth coming from the earth.

Option B: Ground Source Heat Pumps
The principle can be used for a ground source heat pump as well. You can set up a hydronic heating system (which means that you have lovely radiant heat and coolth, instead of warm or cool air) by filling the underground pipes with water. This means that your heating system doesn’t have to work as hard. Lets say you were cooling your house in summer to about 22˚C inside, while the outside temperature was 38˚C – a conventional cooling system would have work to produce a 16˚C change of temperature – the ground source heat (coolth) pump would only have to produce a 7˚C difference.

Diagram as shown in the very useful article in ReNew magazine.
Click image to enlarge

These systems cut about 50% of the energy used for heating and cooling – with a similar reduction in green house gas emissions. These systems are common in Europe, but not widely used here in Australia – which is one of the reasons they’re generally too expensive to apply on the scale of an individual house – but as a neighbourhood it would become quite cost effective. In the plan above I’ve proposed that we run a network of horizontal pipes underneath the footpaths and laneways which would service each individual house or apartment.

A system of underground pipes would carry air or water underground so they could be cooled or warmed to the temperature of the earth below our houses

The water in the system could be provided by harvesting storm water (which I'll deal with in more depth later), this had the added advantage of reducing the load on storm water systems in the event of extreme weather events - which depressingly, are bound to get more frequent.

Secondly, these systems reduce peak load use, which helps to reduce the likelihood of citywide power failures that occur the grid can't deal with thousands of people cranking up their air conditioners on those 40˚C summer days.

Note: Like the earlier posts, the plan shown above is the ideal layout, and doesn't take into account the location of other underground systems. Once I've 'crashed' it together, or considered it, with the other aspects of the design, we should get a more realistic picture.

   

Labels: sustainable energy

3 Comments:

1. Heating Ontario said...
   16 May 2013 at 10:08 am  
   When used correctly, programmable thermostats will keep you and the family comfortable, help you reduce energy costs and save money throughout the year.
   
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   Unknown said...
   18 July 2013 at 11:43 pm  
   This was a very interesting post. I have been looking for many different ways to cool my house this summer. Finally decided to look into an air conditioner repair person. They came in and fixed the unit right up. I never knew that my air conditioner wasn't working properly or that we had to clean it. I am so glad they let me know. Thanks so much for your helpful post as well!
   nutrendmedia said...
   2 April 2014 at 8:47 pm  
   Really great post... Very well explained difference between heat pumps and air conditioner.. Your post has cleared mine all doubts.. Thanks for sharing.. keep posting..Click here.
   

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