THERMAL MASS
What is thermal mass? How do I incorporate thermal mass into my home design? One of the key factors to heating your home and also keeping it cool is thermal mass. That is, a high density material such as tiled or concrete flooring or an internal or external brick wall which can hold absorbed heat or cool and radiate this into your home for many hours. It is essential to get the correct placement of thermal mass otherwise it can serve as your worst enemy, storing unwanted heat.
Thermal Mass Flooring
A high density material such as tiles or concrete will make an ideal thermal mass flooring. However, for your thermal mass to be effective in Winter, it must have access to the sun in order to heat up. Thermal mass will require several hours of sun exposure throughout the day in order to warm to a capacity where it will store and radiate heat throughout the evening. The more sun exposure your thermal mass has, the warmer it will become and the longer it will be able to generate heat. Some aspects which attribute to the value of the thermal mass include the thickness of your thermal mass (the thicker it is, the longer it can store heat), the colour of the mass (darker colours tend to become hotter quicker), the surface coating (a matte finish will attract more heat than a gloss or reflective finish) and also its exposure to air movement (particularly important if you are using the thermal mass to expel heat or conduct cool during the Summer months).
Thermal Mass Walls
The placement of a thermal mass wall inside your home can be a tremendous benefit, particularly if you are able to position it between the northern living area and the Southern sleeping area. An example of this may be a dark coloured brick internal wall which has solar access throughout the day, allowing it to warm up and then radiate heat into the bedrooms throughout the evening. Thermal mass walls can also be external and can be designed to absorb heat to radiate inside. An example of this is a Trombe wall, something which is not widely known but can be very effective. This type of wall features a glass external layer and a high heat capacity internal layer separated by a layer of air. Sunlight passes through the glass and is then is absorbed by the wall, trapping the heat and radiating it into your home. Other important factors It is important to ensure appropriate insulation to your home otherwise the generation of heat or cool will be quickly lost. You should also remember that thermal mass will be a huge liability if placed incorrectly. Ensure thermal mass is shielded from sun during Summer months otherwise it will store an abundance of unwanted heat. Thermal mass can be a very useful tool for keeping your home cool and warm as required and there can be many factors to consider. I highly recommend reading the chapters in the “Your Home” Australian government website relating to passive design, thermal mass via the following link: http://www.yourhome.gov.au/passive-design/thermal-mass where there is a very detailed explanation on how to best use thermal mass to your advantage. Also remember that your glazing will play a pivotal role in enabling thermal mass to work during the winter months. I’ll be talking about glazing in my next blog.
