How to insulate a building with the three methods of heat transfer

Here will be a summary of all the insulating strategies that we have talked about. If we want to insulate a building in the context of all of the heat transfer mechanisms, how can we do so?

First, we will want to insulate with a material that has a low rate of conduction. Ideally, we would use a vacuum insulated panel or something similar, however, because of their relatively high cost and fragility, we will go with something a little more conventional. We will use a material that has a high porosity so that we can take advantage of the low conductivity of air, and ideally the material that we use as an insulating material will also have a low conductivity. With these conductive parameters in mind, we will end up going with an insulating material such as fiberglass or mineral wool. These two insulators both have a high porosity, low conductivity, and are relatively cheap and common to help keep our building's insulation economical.

Next, we will want to minimize the rate of heat loss via convection. Even though the walls of our building are fairly thin, they are still large enough to facilitate convective heat transfer. So, to minimize the movement of air in our walls, we will want a material that has a good resistance to fluid flow. Using the same materials that we used to reduce conductive heat transfer will work pretty well, but there are other materials that will work better. For example, areogel has a better resistance to conductive heat transfer than mineral wool, although it is more expensive than mineral wool. However, for a conventional building application, mineral wool is good enough. We will also need to make sure that our insulating space is air sealed to prevent too much outside air from flowing through our insulation and reducing its effectiveness.

Lastly, how can we use heat transfer via radiation to help insulate a building? By using a reflective material that has a low emissivity and absorption, and therefore a higher reflectance, we can reduce the amount of heating via electromagnetic radiation that will be transferred to the material. If our building is going to be in an area that will experience a significant amount of electromagnetic radiation, then installing a radiant barrier will help decrease the rate of heat transfer that is being transferred to the insulation. However, in areas that experience less electromagnetic radiation, the effectiveness of a radiant barrier will probably be insignificant. A radiant heat barrier will work very well in hot and sunny environments that experience a lot of solar radiation, however, since we live in Alaska, a place with highly variable temperatures and solar radiation exposure, a radiant heat barrier will probably not be necessary for our insulation needs. Especially if the increased insulation capabilities of radiant heat barriers in our environment are not worth the cost compared to increasing the thickness of our insulation, then adding a radiation barrier would be inadvisable.

This summary of how we should insulate our homes does neglect some other important considerations, such as preventing moisture buildup, but this should give an overview of what considerations to take for insulation as they relate to heat transfer mechanisms.


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