Most people already know many of the superior qualities of brick – durability, aesthetics, and low maintenance – but brick masonry is also advantageous when considering the energy efficiency of buildings.

Today’s energy codes require that building walls meet certain thermal performance criteria, usually expressed as U- or R-values. The codes are more sophisticated by taking into account many things including climate, percentage and area of windows, insulation location, and interior heat generated by lighting and people. Despite these added factors, the good news is that clay brick walls can easily meet the energy requirements because of their heavy weight, or thermal mass.


Thermal Mass

Thermal mass, simply stated, is the use of heavy, dense materials to store and then slowly release heat at a later time. Brick masonry wall systems exhibit superior thermal mass properties.

 

Current energy codes recognize the benefits of thermal mass. They do this by requiring lightweight walls to have higher R-values to achieve the same energy performance as brick masonry walls with lower R-values. In other words, brick masonry walls require less insulation than lightweight walls for the same energy performance.

 

Thermal Lag

The thermal storage properties of brick masonry help shift peak heating or cooling loads to off-peak and dampen the peak temperatures. Instead of the outside temperature being felt immediately on the inside, the mass of brick slows down the transfer of heat to the interior or from the interior out. This is known as thermal lag. The thermal lag property of a solid brick masonry wall causes as much as a 6 hour time lag between the peak outdoor temperature and the peak indoor temperature.

 

The benefits of thermal lag can be utilized to economic advantage by shifting the maximum heating or cooling loads to off-peak hours. Utility rates often vary based on demand throughout the day, with rates the highest when demand is greatest. Shifting the peak load to the later part of the day during off-peak hours results in lower electric charges and lower overall operating costs for owners. Many utilities will work with customers to create this off peak demand.


 

Temperature Damping

In addition to shifting the peak heat loss or gain, the heat capacity of brick masonry walls causes a reduction in the total heat loss or gain. This property is called temperature damping and can be considerable, especially for areas with large heat gain differences. Many people have a feel for this property from experience. On the hottest summer days, a brick masonry building or home is typically cooler, even without mechanical cooling. Temperature damping reduces total energy consumption.


E
nergy usage continues to be a prime concern in today’s society and by using clay brick, architects and designers can help optimize the energy performance of their buildings and conserve energy.