Embodied energy
A more holistic view of energy efficiency takes into account the energy required to produce, transport and construct on site the materials used to build a house – the ‘embodied energy’. Increasingly, this type of analysis also accounts for the embodied carbon dioxide. The cost of this embodied energy is built into the cost of the building materials. The more energy intensive the material, the more expensive it is likely to be. Although larger amounts of glass, thermal mass or insulation increase the embodied energy of a house, if well-designed, the total energy used by that house over its life will be less (relative to an ordinary design). For example, using the higher levels of insulation proposed in this book results in operational energy savings that far outweigh any increased embodied energy. Thermal mass installed with good external insulation can significantly reduce operational energy use. If we assume the thermal mass is concrete, its use in construction adds embodied energy, but the energy savings over time result in an approximately neutral energy impact.
Sustainability
If you want to design a more sustainable house there are many other issues to consider besides energy efficiency. Sustainable development is dependent on following sound individual design decisions for every aspect of the house. The sustainable house must balance a wide range of issues in line with your personal needs and aspirations. These include but are not limited to:
• using materials from sustainable resources
• using materials whose mining and manufacture produces a
minimum of pollutants
• using materials that minimise the life cycle impact of the
house on the atmosphere
• using low-maintenance materials
• avoiding building materials that emit chemical pollutants
into the house after they are installed
• recycling and re-using materials in construction – and
facilitating recycling in the building during its operatio
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