The purpose of insulation is to resist heat flow. Heat flows from warmer places to cooler places in three ways – by conduction, convection, and radiation. 

In the winter, heat flows from your heated living spaces to adjacent unheated living spaces and to the outdoors by moving through solid objects such as walls and through air in the form of air leaks. In the summer, heat flows by the same pathways in the opposite direction, from the hot outdoors into the cool spaces of your home. Insulation materials typically work to slow conductive and convective heat flow, so that the warm or cool air released by your furnace or air conditioner stays where you want it – in your home!

The R-value of a material is a measure of its resistance to conductive heat flow, or it’s thermal resistance. Materials with higher R-values are more effective insulators. Fiberglass batt and spray foam polyurethane insulation are effective insulators because they are poor conductors of heat – they have a high thermal resistance. The thicker an insulation layer is, the higher R-value it will have. In contrast, if loose-fill insulation is installed in thick layers, the insulation becomes more compressed under its own weight which reduces the thermal resistance of the insulation and makes it more conductive to heat flow. Similarly, if fiberglass batt insulation is compressed during or after insulation for any reason, it’s thermal resistance will decrease.

Convective heat loss is reduced by insulation that adequately fills cavities in walls, ceilings, and floors to prevent airflow and drafts. Radiant barriers, such as reflective bubble wrap, can complement traditional insulation by reflecting heat radiation back into or out of the living space and preventing solid objects such as walls from absorbing heat.

To learn more, call Urban Insulation today. Or if you’d like to get started, we can provide you with a free estimate!