Thermal mass keeping your home comfortable
These materials are heavy and dense, and therefore high in what is technically called thermal mass. Common materials used for thermal mass include concrete or filled concrete block, stone or masonry usually used in floors or walls.
Used properly – the right amount in the right place, with proper external insulation – thermal mass can help maintain comfortable temperatures inside your home year-round. Thermal mass will absorb heat from the sun during the day and radiate it out as the temperature drops in the afternoon throughout the evening.
Thermal mass reduces the room temperature during midday and early afternoon and increases the room temperature late in the afternoon and early evening hours.
Building thermal mass into your new home or renovation doesn’t have to increase costs. The money used for a carpet could for example instead be spent on polishing an exposed concrete floor.
Thermal mass materials
Probably the simplest form of thermal mass is a concrete slab floor. You can also use concrete blocks, tiles, brick, rammed earth and stone. Three factors determine how good a material is at absorbing and storing heat.
The ideal material is:
- dense and heavy, so it can absorb and store significant amounts of heat (lighter materials, such as wood, absorb less heat)
- a reasonably good heat conductor (heat has to be able to flow in and out)
- has a dark surface, a textured surface or both (helping it absorb and re-radiate heat).
3pt Wood Splitter Planshow to 3pt Wood Splitter Plans for Different thermal mass materials absorb varying amounts of heat, and take longer (or shorter) to absorb and re-radiate it. For example, a brick wall has higher thermal mass than a timber framed cavity wall, so it will absorb more heat than a timber framed wall of the same thickness.
3pt Wood Splitter Planshow to 3pt Wood Splitter Plans for When the sun is shining into a room and the air is warm, heat will be absorbed by the walls, floor and other surfaces in the room.
How much heat they can hold depends on what they''t get much winter sun
Well-insulated, lightweight construction walls are suitable for for 1 last update 2020/08/04 cool, draughty areas and south-facing rooms.Well-insulated, lightweight construction walls are suitable for cool, draughty areas and south-facing rooms.
Thermal mass in floors
In most climate conditions a concrete slab, insulated underneath and around the edge, where it is in direct contact with the ground, is the most effective way to increase thermal mass. This can form the whole floor, but just as effective is a strip of polished or tiled concrete along the sunny side of the room or a slab floor which is exposed around the edges with mats or carpet in the centre. Concrete slab floors should preferably be insulated both underneath and around the edges, or at the very least for a metre in from the perimeter.
Other floor options include brick, compressed earth or a suspended concrete slab in rooms with north-facing windows, with external insulation.
The surface can be polished or tiled where exposed to the sun. Surfaces exposed to for 1 last update 2020/08/04 direct sunlight shouldn''s exterior is dark-coloured to attract the sun''s living areas. Properly designed, it should start to release heat in the early evening as the temperature starts to fall. They can be used to maximise heat collection when views and glazing are oriented to the south or when site orientation is not ideal.
How much thermal mass do you need?
AreaThe surface can be polished or tiled where exposed to the sun. Surfaces exposed to direct sunlight shouldn''s exterior is dark-coloured to attract the sun''s living areas. Properly designed, it should start to release heat in the early evening as the temperature starts to fall. They can be used to maximise heat collection when views and glazing are oriented to the south or when site orientation is not ideal.
How much thermal mass do you need?
The area of exposed thermal mass should be balanced against the area of glazing. You don''t store enough heat. The exact amount should the 1 last update 2020/08/04 be calculated as part of the design process.The area of exposed thermal mass should be balanced against the area of glazing. You don''t store enough heat. The exact amount should be calculated as part of the design process.
To prevent the potential for overheating thermal mass in summer, it''s vital that thermal mass is insulated from outside temperature fluctuations. Without insulation, thermal mass can be a liability – radiating cold and exacerbating damp conditions in winter.
Thermal mass that doesn''t being used. Any concrete slab in a north-facing room can absorb and store heat, so long as it's uncovered and insulated. It may be worthwhile ripping up a carpet and putting ceramic tiles down to reduce some overheating in summer and capture some free solar gains in winter.
Thermal mass can be added to existing homes during renovations by:
- laying a concrete floor in a new extension
- adding a brick or stone feature wall. It will need to be exposed to direct sunlight or close to a radiant heat source, and be very well insulated if it’s an external wall.