Controlling heat gain or loss in buildings

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[edit] Conceptual change in controlling heat gain or loss in homes

Heat energy only flows from a warmer place to a cooler place. The amount of heat flow depends on two things, the temperature difference and the conductivity of the heat flow path.

Traditionally, we limit heat flow by placing more resistance (R-value) between the two temperature differences. Placing a layer of fiberglass batt or some other low conductivity material such as foam or cellulose within the walls or ceiling spaces has usually been done. Cost and the amount of space available limit the amount of resistance (R-value) employed. Walls in particular are limited because of the narrow cavity space.

Our new approach is totally different. It controls the temperature differential across the R-value. Understand first that if the temperature difference can be kept low then the heat flow across any R-value is also kept low. If the temperature difference, sometimes referred to as Delta T, equaled zero then zero heat flow would occur. Using this new approach, zero heat flow conditions have been witnessed even when large temperature differences existed in the attic and the room below. The old conventional way would require an infinite amount of R-value to accomplish this and is impossible to achieve. (INFINITE R)

[edit] Phase change materials

Phase change materials (PCMs) do a strange and amazing thing. They do not change temperature during the change of phase from a solid to a liquid or vice versa. Water is a common Phase Change Material (PCM). Water has the ability to hold one BTU of heat energy per pound per degree F. Water in the solid phase (Ice) also has the same ability to hold one BTU of heat energy per pound per degree F. .The strange and wonderful thing is that during the phase change from liquid to solid, water gives up 144 BTUs before it can pass from 32 degrees F. liquid to 31 degrees F. ice! This is a 143 times the amount of BTUs it takes to change the temperature of water or ice by one degree F at other than 32-degree F temperatures. It works the same in the other direction from a solid phase melting into the liquid phase. This massive amount of heat storage capacity only occurs at 32 degrees F and is called Latent Heat Capacity. Unlike Sensible Heat, Latent Heat does not cause a change in temperature of the substance.

Other materials such as Calcium Chloride (CaCl-6- H2O) do the same thing but in CaCl-6-H2O the phase change temperature is 81 degrees F. Calcium Chloride (CaCl-6-H2O) is used to make pickles crispy, settle the dust on roads, and in concrete to facilitate faster curing. It is very economical and is fire retardant.

A new patented product, incorporates for the first time in America, the amazing power of Phase Change Materials in the construction and building materials industry.

Imagine a layer of insulation (R-value) in a building where the temperature difference across that layer was near zero all the time! Hardly any heat flow through that insulation layer would occur. An example might be where a room thermostat was set at 77 degrees F and since hot air rises the ceiling was about 81 degrees F.. Above the ceiling was an insulation layer of R-value 19. If a thin layer of Ca Cl-6-H2O was on the attic side of the insulation layer, going through the phase change @ 81 degrees F then zero heat flow through the ceiling would be occurring.

Three main things determine the amount of PCM that is needed, the average temperature of the attic, the R-value protecting the PCM, and the time duration. The time duration is controlled by the Diurnal Cycle. (24 hour day/night) The objective here is to provide enough of the PCM to be melting all during the day and refreeze back during the night. One configuration is 1/4" thick layer of PCM and an R6 layer protecting the PCM from the attic air.

[edit] Summation

By having the PCM control the Delta T across the inner insulation layer to near zero, the result is a very low heat exchange between the inside and the outside. Zero heat flow can be achieved by keeping the temperature difference across the inner layer to zero

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