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23/07/09 | One year on. It is just over a year since my father died.  My mother is living in her new home and enjoyi... {more}
24/11/08 | Virgin - arghhh! Oh the joys! Today we undertook the installation of our Virgin phone / broadband cable from the hous... {more}
23/11/08 | Awadukt results This morning we've had our first chance to look at our ground to air energy transfer, in the absence... {more}

The Heating & Cooling

"Heating and Cooling" should probably be combined with lighting and ventillation and thrown under some other banner heading, like "environment management" or "living space control". Basically, the best building in the world is nothing more than a cave - and a dark one at that - unless you can manipulate the environment to make it more comfortable to be in.

The environmental condition in which most of the population feels "comfortable" is quite difficult to define and even more difficult to manage in an energy conscious and environmentally responsible way. The air needs to be fresh and moving, but not so much as to be noticable! It needs to be at the right temperature, with an acceptable temperature gradient from floor to ceiling. The moisture content (relative humidity) needs to be maintained within a narrow band. The radiant temperatures of the various surfaces need to be within a degree, or two, of the "ideal", otherwise we feel uncomfortable. Add to this catalogue of requirements the need to see clearly, but not suffer from glare, nor to waste vast amounts of energy on lighting unecessarily - the simple pendant light in the middle of the room, with a switch by the door looks very outdated. Which is precicely where the bimetallic strip thermostat that controls the heating should find itself - outdated! As for cooling - for most of us in the UK, that comprises nothing more complex than opening the window - which may well do more harm than good!

I find it quite amazing that we now expect air conditioning in our cars - however lowly the specification - yet apparently have no comprehension of managing our home environment to provide some degree of comfort!

The various systems employed at Bluebell Bungalow are summarised below and will be explained in more detail on the adjacent pages once time permits us to put them into words!

Shallow pilefield groundsource energy - Piles under the building used to source and sink energy to / from.

Water to water heatpump - Moves energy from one place (source) to another (sink), with an attendant shift in temperature to make the energy usable in "normal" systems.

Underfloor heating & cooling - PIpe matrix buried in the concrete slab (which acts as a huge thermal "battery"), used to heat and cool the living space.

Ground to air heat exchange - A big pipe (315mm diameter) with a special internal coating (silver atoms to combat microbial growth), buried 2m down under the drive. Feed it with air from the surroundings (+35C summer, -5C winter) and it pops out of the other end at 16C to 11C - all for turning a modest fan! (I'm guessing here, but 200W of fan is probably way too much and it's just done 50% of the energy demand!!)

23 Nov 2008 This morning we've had our first chance to look at our ground to air energy transfer, in the absence of any building heating (other than waste heat from the lights) and snow falling! The system (REHAU Awadukt) takes in external air (0.6°C today), filters it to remove large particles of dust and passes it up the length of the driveway about 2m below ground level, through a specially developed polymer pipe. As the air travels through the pipe it takes energy from the ground to warm it, arriving at the house at about 10°C, where we use it as the input supply to our passive heat recovery vent units. These simple “plate to plate” units extract warmth from the stale air extracted from bathrooms and kitchen and transfer it to the fresh, pre warmed air from the Awadukt, resulting in air entering the bedrooms and living space at about 15°C – not a bad result for the cost of running 4 small fans!
The system will work all year round, so in summer (remember what that means?) it will take in hot air (maybe 25°C to 30°C, if we are ever that lucky) and pre cool it ready for delivery into the living spaces. This, in conjunction with our reversible floor heating / cooling system, will provide for all year round comfort conditions with minimum energy consumption and running cost.

 

Heat recovery ventillation - Passive system utilising plate to plate heat transfer to suck the energy (warmth / cool) from the stale air extracted from the bathrooms and kitchen, transfer that energy to the fresh incoming air from the Ground to Air system and push it into the various living spaces - bedrooms, lounge, etc.