environmentalhouse.com

R12 Insulation Value Plus Thermal Mass

Because we use chipped wood and polystyrene as part of the material, our block has an insulation value. No need to purchase insulation.

R-value means a material’s resistance to the transfer of heat. The higher the R-value of a material, the better it is at resisting heat loss (or heat gain). Currently, most wall R-value calculation procedures are based on calculations developed for conventional wood frame construction.

Thermal Mass Effect is an energy saving characteristic of dense material. Thermal mass is a material’s capacity to absorb, store and release heat over time. The issue of thermal mass and its effect on the energy performance of buildings is one of the most confusing issues facing designers, builders and buyers of buildings today.

High-mass building materials can offer significant energy benefits in exterior walls. Some advertisements claim R-30 from a lightweight masonry block wall system. Log home product literature claims that log walls insulate as well as fiberglass because of the thermal mass. It has been debated that a new fiber-cement building system achieves R-24 even though the "tested" R-value comes in at only R-12.

R-values are measured by testing laboratories, usually in something called a guarded hot box. Heat flow through the layer of material can be calculated by keeping one side of the material at a constant temperature, say 90°F (32°C), and measuring how much supplemental energy is required to keep the other side of the material at a different constant temperature, say 50°F (10°.C).

Another property that can affect their energy performance in certain situations: heat capacity. Heat capacity is a measure of how much heat a material can hold.

"Mass-Enhanced R-Value"
"Mass Effect" or "Effective R-value," they are generally referring to the ability of high-mass materials; when used in certain ways, better energy performance is expected if only the commonly accepted R-value of that material is considered.

In real-life situations the inside and outside temperatures are not constant. On a summer afternoon in Albuquerque, New Mexico, for example, it might be 90°F (32°C) outside. As night falls, however, it cools down outside. The air temperature may drop to 50°F (10°C). As the temperature difference across the wall is reversed, the heat flow is also reversed, drawing heat back towards the outside of the building. Thermal mass saves energy by releasing heat back into the house as temperatures drop.