Embodied energy is one of the terms used to measure the impact of a product on our environment. An understanding of these terms is important for informed debate on environmental sustainability.
It measures the amount of energy involved in the extraction of raw materials, their transportation to the point of manufacture, the production process, delivery to the building site and installation of the product.
Embodied Energy and Life Cycle Analysis
We have explained embodied energy at the start of this page. However the true life cycle impact of a material is not accurately measured by its embodied energy alone. The life cycle of the product takes into account emissions during its usage and in the case of bricks the ability to recycle the product.
The embodied energy inherent in bricks should be considered as an investment that can lead to long term environmental benefits through;
- Reducing the need for artificial heating and cooling when used in combination with passive design principles
- Having a long life and being durable, reducing the need to reinvest in embodied energy
- And being colourfast and virtually maintenance free, reducing ongoing energy usage
In addition to the obvious environmental benefits of bricks, energy bills are reduced providing considerable savings for the home owner.
Putting Embodied Energy Into Perspective
To put the embodied energy into perspective consider the following question.
How many light globes does it take to change a house?
Changing one light bulb from a 100w incandescent to a 20w compact fluorescent will save 6.5 tonnes of greenhouse gas emissions over fifty years²
This is larger than the greenhouse gas emissions associated with the embodied energy of the bricks in a standard brick veneer house.
It certainly puts embodied energy into perspective doesn’t it?
Think of brick as a thermal battery:
“Thermal mass acts as a ‘thermal battery’. During summer it absorbs heat, keeping the house comfortable. In winter the same thermal mass can store the heat from the sun or heaters to release it at night, helping the home stay warm."
- Your Home Technical Manual
- Think of brick as a natural air-conditioner:
- In summer, brickwork’s thermal mass cools down overnight and stays cooler during the heat of the day.
Well-designed building:
Thermal mass helps to achieve thermal comfort
- Thermal mass reduces the need for air-conditioning
- Thermal mass reduces greenhouse gas emissions over the life of a building
Research at the University of Newcastle has demonstrated that thermal mass can naturally moderate temperatures. This chart shows results from a summer heatwave. The external temperature fluctuations were moderated by brickwork to a range more consistent with human comfort. The brochures and background paper below provide more detail about the research.
Thermal Mass and the R-Value
The most common measure of the thermal performance of a building material is its R-value. An R-value is a measure of the thermal resistance of a material. Although the use of a single number is convenient and easily understood, the R-value is only a measure of the material’s ability to insulate. The R-value is not a complete measure of a material’s thermal performance. Thermal mass is not easily measured, but is it easily found in dense materials like bricks. It is important to remember that an appropriate combination of both insulation and thermal mass (along with ventilation and orientation) will create a well designed home.