thermal mass

thermal mass in passive solar design

Competent passive solar design requires an architectural design to have sufficient thermal mass to store the sun’s radiant heat energy.  Thermal mass contributes to a building’s ability to absorb, store, and release heat to regulate indoor temperatures for energy efficiency.  Appropriate thermal mass correct plan locations ensures building materials absorb radiant heat energy during daylight for release during evening hours.

The thermal mass acts as a heat sink to balance the building’s ambient air temperature between daylight and evening hours.  The building mass is particularly useful during the lower winter temperatures.  The heat sink releases the stored radiant heat into the building at night to maintain a consistent internal ambient temperature.  Reliance on air-conditioning/HVAC is avoided if a building is appropriately planned and building mass proportioned during sketch design.

thermal mass materials

High-density materials like concrete, bricks, and tiles require a lot of heat energy to change the temperature.  This characteristic is described as high thermal mass.  Conversely, lightweight materials such as timber have a low rating.  Understanding the passive solar design principle of a required heat sink in architectural design defines thermal comfort and reduces utility bills.

The building stores solar energy during the day and re-radiate during evenings if competently positioned in the architectural spatial layout. This passive solar design principle moderates internal temperatures by averaging out diurnal extremes.

Poor placement of the building’s mass can exacerbate the worst extremes of the micro-climate.  Lack of foresight during the architectural sketch design can be a huge energy and comfort liability.  The building mass can also radiate heat all night as you attempt to sleep during a summer heatwave. Conversely, it can absorb all the artificial heating you produce during cold winter nights.

To function effectively, the heat sink’s mass must be integrated with sound passive solar design techniques. The architectural design should have appropriate areas of glazing facing for radiant heat gain during winter.  Additionally, fenestration requires sufficient levels of shading, architectural spaces need cross-ventilation and insulation.  These passive solar design principles are utilized in all Threadgold Architecture + Construction architectural designs.

thermal mass during winter

The architectural design should permit the mass to absorb heat during the day from direct sunlight or from radiant heaters. It re-radiates this warmth back into the home throughout the night.

thermal mass during summer

Architectural designs should permit cool night breezes and convection currents to pass over the building’s mass, expelling stored energy. During the day protect the thermal mass from excess summer sun with eaves, shading devices and insulation.

The photograph features a beachy style home with solar passive principles; including; rammed limestone feature walls.  The architectural design has walls acting as a thermal heat seal, solar orientation and roof top photovoltaic panels.  The residence also incorporates polished honed concrete floors with a hydronic in-slab floor heating system.