9. THERMAL MASS

Thermal mass is a measure of a material's capacity to absorb heating or cooling energy. Materials such as concrete or bricks are highly dense and require a lot of energy to be heated or cooled. On the other hand, materials such as timber are less dense and do not need to absorb much energy for smaller changes in temperature. The more energy it takes to affect a temperature change of the material, the higher the thermal mass. The time it takes for the material to store and then release the heat energy is referred to as the thermal lag.

The thickness of a material impacts its energy storage capacity. For example, steel studs have a greater thermal mass than wood studs.

The density of insulation materials differs and further affects thermal resistance values.

The simple application of thermal mass can work to passively heat or cool a building, as internal changes in temperature can be moderated to remove extremes of heat or cold. The reverse is also true; inappropriately located thermal mass can cause external temperatures to disproportionately affect Internal thermal comfort.

Before increasing thermal mass to an area of a building, consider:

Will this location be best to exploit solar gain? Can this location be shaded to avoid gain when it is not

required?

HOW TO USE THERMAL MASS

How can this be applied to low rise wood framed construction ?

When using thermal mass it is critical to understand that it behaves differently than insulating material. Thermal mass is the ability of a material to store heat energy and then release it gradually. Insulating materials, on the other hand, prevent heat from passing through them. In fact, many high thermal mass materials display poor insulation characteristics.

The embodied energy in some thermal mass materials may also be taken into consideration. Some materials, such as concrete, require a lot of energy to manufacture and are inappropriate in relation to the actual energy savings they might deliver.

THERMAL MASS

THERMAL MASS

Mass situated on the south side of a building is most efficient for heating in Vancouver. The mass can absorb heat from the sun and then release this energy during the night. To avoid overheating, areas with high thermal mass should be shaded from this sun in the summer, or situated/landscaped to take advantage of cooling winds.

concrete floors or concrete block partition walls are very effective at absorbing thermal conditions (heat or cold).

Use the south side for thermal mass, but apply appropriate shading for summer months

Apply thermal mass on the ground level

SLAB ON GRADE CONSTRUCTION

Slab on grade (SOG) is a very common method to create thermal mass. Generally about 4" thick,

SOG should be insulated from the ground below to avoid losing heat in the winter.