Heat energy always flows from a warmer to a cooler place. The amount of heat flow depends on two things, the temperature difference between the two places and the conductivity of the heat flow path. Traditionally we limit the heat flow by placing more resistance (“R” Value) between the two temperature differences. The Infinite R approach is different. We control the temperature across the “R” Value.
Ordinary thermal insulation such as fiberglass, cellulose, or AEROGEL works by slowing the rate at which heat energy flows from a warm to a cooler area. Again the rate of transfer is controlled by two factors: The temperature difference (Delta T) from the warm to the cool side, and, the thermal resistance between the two sides.
If temperature differences can be kept low, then heat transfer (flow) is also kept low. If the temperature difference, sometimes called “Delta T” equals zero, then zero heat flow would occur. Using this approach zero heat flow conditions have been witnessed even when large temperature differences existed between the spaces. Traditional insulation materials would require an infinite amount of “R” Value to accomplish this and is impossible to achieve.
Phase Change Materials (PCM’s) DO to 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. 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 this is that during the phase change from a liquid to a solid, water gives up 144 BTU’s before it can pass from a 32° liquid to a 31° solid (Ice). This is 143 times the amount of BTU’s that it takes to change the temperature of water or ice by one degree f at other than 32°degree temperatures. It works the same in the other direction from a solid phase melting to a liquid phase. This massive amount of heat storage capacity only occurs at 32° and is called “Latent Heat Capacity”. Unlike sensible heat, Latent Heat does not cause a change in temperature of the Substance.
Sensible Heat is ordinary heat and it determines the temperature of a material. If you add thermal energy the temperature increases, if you remove the thermal energy, the temperature falls. Latent Heat is a bit harder to understand. It is the heat that is released when a POCM = PCM changes phase from a liquid to a solid. To melt the PCM and change it back to a liquid requires the same amount of extra latent Heat energy. In the case of water/ice it is 143 times as much to Phase Change than to raise the temperature outside of the phase change temperature range. This means a small amount of PCM at the phase change temperature can control a relatively large amount of heat energy.
The temperature difference across the internal “R” Value of a wall or ceiling has never been challenged and was long thought to be immutable. However by using Phase Change Materials (PCMs) it is possible to control this temperature difference for a period of time. The length of time is determined by the amount of PCM, the temperature difference, and any “R” Values present. A small amount of PCM to control the temperature difference across a wall for 24 hours is all that is necessary. During daylight hours the PCM will be intercepting thermal energy, using it to melt, then each night it will give up the intercepted heat and refreeze. The PCM changes from a solid to a liquid during the day then a liquid to a solid at night All the while that this is going on day after day, the PCM remains at a constant temperature. It is this characteristic of PCMs that we have seized upon.
An easier to follow answer:
Turning your home into a Cooler? The way your ice cooler works is: The foam insulation inside the shell delays the transfer of heat either in or out of the box. Ice is added to the contents of the cooler which then attracts any heat either passing through the foam walls or from the material inside the cooler requiring chilling, absorbing that heat, which it then uses to change phase (melt). The interesting thing of course is that the ice does not change temperature while the phase change is going on. So as long as there is a sliver of ice in the cooler the phase changed ice (now water) inside the cooler and the remaining ice will all be 32°. This is why you do not want to pour the water our before all the ice is melted!
Imagine your house as the cooler with no ice. It is well insulated but there is no phase change material. Ambient heat will slowly but surely enter the house. If however a layer of phase change material is placed inside the walls and attic, it will act like the ice in your cooler and keep the walls and ceiling cool. By adding Infinite R to your home any heat getting by your traditional insulation materials will be absorbed by the PCM and used to convert the solid PCM to a liquid. When heat above the melt point is removed (when the sun goes down) and the temperatures drop below the melt point, the PCM will release the heat AT THE PHASE CHANGE TEMPERATURE as it goes from a liquid to a solid again recharging for use the next time ambient conditions go over the melt point. By removing the heat above our melt set point the PCM dramatically reduces AC loading on the building. Where your normal wall of ceiling temperatures might be 90° or even 100° in the summer, it will be limited to the phase change set point by the PCM, making the home much more comfortable and reducing the AC loading from what could be a 25° Delta T (thermostat set at 75° and 100° radiating through a ceiling from superheated attic) to 5° or less!
There are hundreds of Phase Change Materials and we have the ability to custom formulate PCMs to meet many phase change temperatures. The object is to create a PCM with a melt point just above the ideal temperature you need for your application such that the difference between the desired temperature and the melt point (delta T) is reduced to as close to zero as possible.