Technical
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RESEARCH & DEVELOPMENT
THE THERMAL INERTIA TEAM
The team are working together to provide you with the most comfortable, energy efficient and affordable building. PolySteel UK has initiated a series of tests at the National Physical Laboratory in partnership with NPL, Kiers, David Ball Group, Aggregate Industries, BASF the chemical company, H+H Celcon, Glasgow Caledonian University, The Concrete Centre and the Insulating Concrete Form Association to demonstrate how different kinds of walls with different thermal mass when submitted to dynamic temperature changes to one side of a wall (what happens in real life) can effect your energy useage giving support to the fact that 'U' value isn't everything.
Tests are being conducted on various wall types including: timber, brick, concrete block, exposed concrete and polySteel. The tests will be able to provide evidence to show how effective each wall is at saving you money on your energy bills. Results are expected early February 2009.
Jan 2008
POLYSTEEL UK IN CONJUNCTION WITH THE SUSTAINABLE SOLUTIONS GROUP EXPLORING THE POSSIBILITIES AND BENEFITS OF GROUND LINKING
Vision: Maintaining the comfort of your home between 18 21 deg Celsius throughout the year for no cost and without connection to any of the utilities.
Heating cost: A heating system has to be sized so that it is capable of warming the existing air in the home multiplied by the amount of times that air needs to be changed over a given time (providing a healthy living standard). On top of that it has to be capable of providing enough heat to make up for the heat being lost through the external fabric of the home to the lower outside temperature. If the heating is not sufficient to fulfil these requirements the home will simply not warm up.
There are proven methods to work out the loss of heat through the external fabric of the building as there are for assessing the ideal number of air changes required for various parts of the home. These added together will give the total heating load, which is usually based on the lowest expected temperature for outside (for this exercise assume 0deg Celsius) whilst assuming various comfort temperatures between 18deg and 21deg C. for each zone inside the home.
When calculating the heat loss through the wall it is assumed that to be the difference between the inside temperature and the outside temperature for example: Living room 21degC. and outside 0degC. = 21degC. (21-0).
Imagine: Walls of a home made so that their temperature never dropped below 13degC. The heat loss through the wall would then arguably be 8degC. (21-13) a saving of 13deg uplift on the heating requirements giving quicker comfort temperature recovery and instant savings on fuel. A sort of heat curtain between yourself and the outside which could possibly enable the uplift to be provided for from onsite renewables.
The theory: Mother earth has a near static temperature just below the surface of 13degC. The only way at present that a PolySteel home makes use of linking the earth mass to the wall is through the contact point at which the wall core touches the foundation, allowing this wicking of heat either way uncontrolled. At times the linking of the wall to the earth efficiently to effectively give you the mass of the earth in your wall can as shown above reduce your need for heating, at other times (when the outside temperature is greater than 13degC. but less than 21degC.) It is possible that the arrangement will in fact cost more for the heating than is otherwise necessary.
Basic solutions to explore: Insulate the mass of the wall from the mass of the earth so that the linking benefits can still be employed at will but the downside of linking as described above can be eliminated.
The wall must be provided with sufficient heat from the earth mass to function in the way described as and when required. This could be by placing pipe work within the concrete core (liquid being the heat carrier) which will give good heat transfer between the carrier and the concrete sufficient to meet the demand when required. In support of this, the heat transferred to the wall mass only has to improve on the heat lost through the insulation as a minimum, supported also by the lag given by the thermal inertia of the wall. Ambitions to improve the effects on the living room cooling by way of radiators etc would of course have to be costed as the research evolves.
The heat carrier medium can be controlled through valves which could be simple logic gates acting on temperature information provided from outside, wall core, living area and earth (source) mass.
Example 1 Heating. If temp inside is <18degC and if temp outside is <13degC then open valve (calling on heat from earth mass) if above 13degC.
Example 2 Cooling. If temp inside is >21degC and if outside temp is >21degC then open valve (calling on earth mass to cool) if below 21degC.
Example 3 Regulating. If temp inside is <18degC and outside is >18degC then close valve if ground mass (source) is lower than 18degC thus allowing the room to get maximum benefit from the external heat until max 21degC when the valve would automatically open to re-cool the wall.
Challenges:
Assessing the most effective way of carrying heat and what medium to use
Assessing the coefficient of heat transfer between the earth mass and the pipe arrays in the ground
Appraisal of a suitable insulating method between the concrete wall and the foundations
Formulating the most suitable concrete for the purpose
Formulating the local heat transfer characteristics of the earth mass into which the pipes or other heat transfer arrangement is placed
Maximising the storage of heat within the earth mass at certain times to retrieve when needed. The same for cooling in the summer.
Working out the cost benefits against initial installation of ground/water source collection arrays.
Further evolution of the system to include radiators taken from the wall core to better and more efficiently regulate the internal temperature of the home or office.
If the challenges can be overcome with relative ease to the benefits enjoyed the consequences for using high mass concrete walls in providing positively efficient heating for homes and offices could be far reaching.
Paul Boyce (Managing Director of PolySteel UK) is eager to investigate the vision that may give renewed support for high mass buildings. Please contact Paul if you are interested in investigating the possibilities further with views to set up a project research team.