Thermal Mass Is Achieved by Placing Concrete & Other Heat Absorbing Materials  Into A Building Structure

PUR wall with HTM

A Sipcrete structure does this in a very efficient way by placing the inner Concrete/Plastered facing within the home backed by a highly efficient Insulation barrier, the Insulation prevents the stored heat in the inner facing (Stored Energy In The Battery) leaking out of the home out into the atmosphere.

No other construction Method achieves this as efficiently as Sipcrete.

A study on Thermal Mass in Building Structures was carried out by the world Famous Building Research Establishment BRE,

The outcome of this study showed that after solid concrete walls Sipcrete was the most efficient construction system  Surpassing Bricks & Blocks, Timber Frame & Sip construction methods.

They did not however point out that the Sipcrete Structure retain its heat / thermal mass longer than a solid concrete wall because of its Insulation Backing in the thermal core, You can read this report by going to the Sipcrete Downloads Page


Information & Links to pages that can help understand principles of design and application of High Thermal Mass Construction Methods

Don’t build with straw bales, tires, logs, or foam foundation blocks and then expect it to be passive solar!  Concrete is the best material for many reasons, but foam foundation blocks (ICFs) such as Rastra®, Faswall®, Tech-Block®, and Conform® were simply not designed for passive solar homes.
The main problem with interlocking extruded polystyrene (“EPS”) foam foundation blocks (“ICF”s) and Faswall® wood and concrete blocks is that the insulation is on both sides of the wall.  Insulating the exterior of your foundation wall is good thinking, but insulating the interior of the wall simply prevents the release of any heat which has been stored within the concrete.  Why pay for all that concrete and ICFs then never get a chance to “use” the heat storage?  The basic principle of sustainable, passive solar heating/cooling is that the house AND the ground around it stores heat all summer and releases it all winter.  You need to look at the home itself as a means to store heat.  The analogy of a battery is often used to describe the way an HTM high thermal mass home functions: storing energy (heat) when it is available, using it later, when it’s needed.  Please note that we are not talking about storing enough heat to get through a couple of days without any sunlight; this is seasonal passive solar heat storage!
A common misconception is that straw bale, timber frame Sip Houses and log homes have large thermal masses.  This is simply not true.  They have very low thermal masses.
Thermal mass is a relative measure of an object’s ability to store heat, “K” value.  The complete inability of straw bales and logs to store heat is what makes them such a poor choice for a passive solar home or an attached greenhouse
!  People and plants alike are much healthier in a consistent, radiant heat rich, naturally lighted environment.  If your home is not storing the heat brought in through the windows quickly enough, temperatures rapidly become too high for your comfort and will eventually kill your plants.  That’s why you’ll never see an attached greenhouse like this on a straw bale home.  Straw bale homes have other problems too numerous to address here, but one to keep in mind is the danger to your family’s health.  Airtight homes are bad enough to begin with, but straw, wood, and paper are fuels that promote black mold growth in moist, unvented locations.  Cracks in the straw bale plaster open the wall’s interior to indoor air humidity.  Meanwhile, a surface bonded block wall is waterproof, can be further sealed with non-porous latex paint, and provides no fuel to promote exotic growths that could affect your indoor air quality.