22/10/2026
Designing & building a lifestyle home in Tasmania Tip #4 –THERMAL MASS AND GLAZING!
With heating costs sky high, designing a building that will heat itself almost for free has to be an appealing prospect!
For free heat, homes in Tasmania should be designed to permit the winter sunlight to enter large North facing windows and warm the building’s interior. Although winter sun may feel weak when compared with summer sun, once trapped inside, it can provide much of a home’s heating needs.
To understand why, it’s important to understand the difference between visible light and invisible infrared light. Visible light from the sun passes easily through glass. Once inside a building, and absorbed into the materials of that building, visible light becomes trapped. That trapped visible light will then heat any thermal mass it bumps into. That thermal mass will then radiate infrared light/heat either quickly (e.g. metals) or slowly (e.g. stone). The good news is that infrared light does not like to move through glass. Glass basically acts as a kind of one-way valve.
This is why a well-designed home with North facing glazing to let visible light in, and thermal mass to capture it, and then re-radiate it slowly later as infrared heat can create a very cosy and energy efficient home.
This concept isn’t a modern invention. Our ancestors lived in caves with the entries facing the sun and slept on the warmed floors. They just didn’t have the glazing to keep the heat trapped but they were 75% of the way there!
One major drawback of using free sunshine for heating is that it’s not available at night or on rainy, overcast days. To compensate for this erratic supply, we incorporate heavy materials, that slowly dissipate their heat, into the fabric of the house as thermal mass.
Internal walls made of brick, stone, mudbrick or concrete work well so long as the low winter light can reach them. Even better are polished or burnished concrete floors, or a tiled floor. An insulated concrete slab also helps massively. Timber, vinyl or carpeted floors, or plastered walls do not act as thermal banks.
This is the reason why old, solid brick or stone buildings can feel cool on a hot day and, once warm, will stay warm long after the fire has gone out. Any sustainable, passive solar house must have an appropriate amount of these heavy materials in order to preserve heat and avoid big swings in temperature.
Another drawback of using the sun for free heating is that if you have too much North facing glazing, you can end up living in an overheated greenhouse in the summer. To stop that happening, we design homes with large eaves that stop the summer sun from entering the house and hitting the floors or walls that act as the thermal banks.
We also build in natural ventilation routes for hot air to escape and shading to avert the sun at the height of the day.
The art of designing a house with the right amount of glazing and thermal mass so that it is comfortable year around is not something you pick up overnight. We’ve been doing this for nearly 20 years, so if you’d like the benefit of our experience then drop us a line or give us a call. We’re always happy to have a chat.
If you are keen to make the move to living in a beautifully designed home on a lifestyle block in Tasmania — irrespective of whether you are just looking at blocks or whether you already have approved plans - please give us a call on 0458 441 711.
There’ll be no sales pitch. Just an honest conversation about what building in rural Tasmania actually involves, and whether what you have in mind is achievable.
That conversation will cost you nothing and could save you a great deal.
Follow us to receive regular tips on how to design and build a home well. We have been doing this for nearly 20 years now so we really do have some valuable advice to give!
For more information and examples on some of our unique rural lifestyle new builds in Southern Tasmania please visit our website - bluegumbuilders.com.au
