The comfort of our home or I would rather say comfort of our being, depends on thermal stability. To maintain the temperature at a stable level we would require a material that can store heat. The most common one that is currently being used is concrete slab and masonry walls. To contribute to the thermal stability, it would have to be included inside the insulation envelope and not exposed to the outside environment.

With timber framed homes or modular walls this is limited to concrete floors on ground for most of the time, but there are other options as well that can be incorporated into lightweight construction or even existing building.

Just recently I have been looking into phase changing materials that can absorb and store large volumes of excess heat during the day time hours and to release that same heat at night to warm the structure as temperature drop. This would be very beneficial to prolong the passive heating / cooling period inside your home.

It is much more efficient than heavyweight thermal mass with the ability to change the phase at only 23 deg and would significantly impact on the energy usage of the house. It releases heat without getting cold as opposed to concrete or masonry wall.

 With a well-designed home and good placement of thermal mass that can effectively work your home should be able to reduce the need of active heating or cooling to minimum.

Those videos might be bit lengthy but very informative on the product  and great solution also to improve your existing homes with additional thermal mass.