Thermal mass is a great way to increase the energy efficiency of your dream sustainable house, helping to keep your home warm in winter and cool in summer.
In the right climate, the more thermal mass your house has, the better it will insulate you from temperature fluctuations.
In this article we’ll explore why thermal mass can be a great design feature for an eco-friendly home and what materials are best for increasing it.
- What is thermal mass and how does it work?
- How climate affects whether or not to use thermal mass
- The benefits of incorporating thermal mass
- 7 stunning ways to incorporate thermal mass to create a sustainable, efficient, and comfortable living space.
What is thermal mass?
It’s a material that has the ability to absorb and store heat and release it later. Concrete, stone, bricks and rammed earth all have this ability.
The idea is to use one or more types of mass in your house design so that in winter the sun’s warmth can be absorbed and radiated throughout your home during the day as well as after the sun goes down and the temperature cools.
Incorporating mass into your home design, like all the other elements of solar passive design, needs to be considered holistically alongside factors such as house orientation and layout, insulation, window size and placement and shading to ensure maximum energy efficiency and comfort for your home.
Due to the technicalities and interplay between solar passive elements, Architects and building designers often use computer modelling to simulate and evaluate expected performance of all the elements to ensure a good result is achieved.
Climate and thermal mass
In a climate where it’s hot in summer and cold in winter it’s important that the house is designed in such a way that the thermal mass you use to warm the house in winter doesn’t also warm the house in summer! It’s important that thermal mass is shaded in the summer months to prevent this from happening.
Our house is in the warm temperate zone of Australia where the temperature fluctuates between night and day, therefore we used a polished concrete floor to help heat the house in winter. Shading in the form of eaves and fixed awnings shade the concrete in summer to keep it cool and the louvre windows and doors are opened to cool the house.
In climates that are almost always hot OR almost always cold (i.e. don’t fluctuate much), thermal mass can actually be detrimental as it only has the capacity in those environments to either warm up or cool down (to match the outside temperature), not fluctuate at night time to bring the house into a comfortable temperature range.
This is why you find in warm or tropical climates buildings are constructed with open designs and lightweight materials that do not retain heat while in cold climates buildings are usually highly insulated with very little exposed thermal mass.
The benefits of incorporating thermal mass
The benefits of using thermal mass in the right climate (where temperatures fluctuate between day and night) include:
- Reduced need for artificial heating
- Reduced reliance on fossil fuels
- Lower energy bills
- Increased comfort and enjoyment of your home
What materials can be used for thermal mass?
It’s often used in the structure of the house, usually in the floors or walls, often becoming stunning feature of the home.
The best ways to incorporate thermal mass are:
- Polished concrete floors
- Concrete walls
- Rammed earth walls
- Brick (masonry) walls
- Tile floors over a concrete slab
- Stone walls
- Stone floors
Polished concrete floors
Rammed earth walls
Brick walls (internal)
Tile floors on a concrete slab
I’m sure you’ll agree that adding these clever materials to your home not only helps maintain a good interior temperature but can also be a stunning feature!
Which is your favourite style? Let us know in the comments!