Thermal Mass

Thermal Mass is a sustainability approach that focuses on the materials you use in your build, and how they absorb, store and release heat.

It’s like having a big, warm hug for your house, direct from the sun. And it’s a simple way to keep the temperature of your house comfortable without using as much heating or cooling -  simply by letting the materials do their thing! 

What is Thermal Mass?

Thermal mass is all about choosing materials for your home that help reduce temperature fluctuations throughout the day. 

Materials with high thermal mass take a long time to heat up and cool down. So in cold weather, thermal mass absorbs heat, stores it and then slowly releases it at night to keep your house warmer. And when it’s used the right way, it can also keep your home cool in warm weather.

Designing with thermal mass can help maintain a comfortable temperature all year round, even in areas like the Mornington Peninsula where the summers can be hot, and the winters quite cold.

It improves comfort levels and reduces the need for mechanical heating, which in turn reduces your energy bills.

What materials have high Thermal Mass?

Not all materials are good choices if you’re looking at using thermal mass in your sustainable home project.

Brick, for example, has high thermal mass, but timber floors and brick veneer don’t.

Other examples of materials with high thermal mass are concrete, rammed earth, stone and even ceramic tiles (when used in combination with a mass structure).

While we often think of floors (like concrete slabs) when we think of thermal mass, it can also be used vertically - for example, using internal walls made of brick or stone.

The best form of thermal mass for your home will depend on things like the local climate, your chosen building design and how you’re going to use the space.

Imagine materials like concrete or brick that soak up heat from the sun during the day, and then when it gets chilly at night, they slowly release that warmth back into your home. 

Passivhaus and Thermal Mass don’t play well together

When you’re looking at sustainable options for your new home or renovation, Passivhaus might be something you’re considering.

So it's worth noting that Passivhaus and thermal mass often don't play well together. 

This is because Passivhaus designs prioritise precise mechanical temperature control and efficient insulation, and large thermal mass can introduce unwanted heat fluctuations that disrupt this delicate balance.

Make sure you consider both options, and chat to me about the benefits and downsides of each before you make a decision for your home.

Ready to consider sustainability for your project?

Determining if thermal mass is right for your design involves evaluating several factors related to your building’s location, climate, and intended use.

The best way to decide if this is the right sustainability approach is to chat with an experienced sustainable architect - like me!

For an obligation-free chat about how you can make your home design sustainable - by using thermal mass, or a range of other sustainable design options - get in touch with me here.