Faculty: architecture topic : constructive system of dwelling house teacher

Hemp lime composite (hempcrete) – This building material is composed of hemp, lime binder and water. It offers a range of ecological benefits and provides good insulation and excellent permeability to water vapour.

Roof systems

High-mass roof systems

Roof systems are usually low mass. This is because thermal mass cannot improve thermal performance unless it is exposed internally, and exposed roof mass is unusual except in multilevel homes or apartments.
Where high-mass systems are used, they are usually part of an overall building system. High-mass roof system options include:

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  Earth-covered construction – When carefully designed, these systems can provide sufficient thermal lag to moderate seasonal cycles, so that summer earth temperatures reach the exposed ceiling mass in winter and vice versa. These homes require no maintenance for the roof and are very durable. Care must be taken to waterproof the home correctly. They have high site disturbance during construction, but minimal on completion. They have high embodied energy and are high cost. Earth-covered construction also eliminates roof area, so any rainwater collection is limited to out-buildings.
  

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  Green roofs – Rather than earth, these use a lightweight manufactured material as a medium to grow plants. Thermal mass is generally inaccessible due to the structure, and insulation is medium to high and provided by conventional insulation rather than the covering. They have medium to high embodied energy, depending on support structures. Other environmental benefits include food production, increased ecological habitat and biodiversity, reduction of heat island over built-up areas, air quality improvement and on-site stormwater detention. They are low to medium maintenance, depending on the plants grown.
  

Low-mass roof systems

Low-mass roof system options include:

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  Tiles – Concrete tiles have slightly lower embodied energy than terracotta. They require more structural support than lightweight materials and can add to heat gain unless well insulated, because they are external, uninsulated thermal mass. While recycling and reuse rates are improving, this is still lower than other materials. Some manufacturers claim up to 40% recycled content in concrete tiles. High transport costs make them inappropriate for remote sites.
  
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  Metal sheeting – This has high embodied energy per kilogram, but because it is thin, the embodied energy is low per square metre. Metal roofs with high performance pre-bonded baked enamel coatings are very durable, easy to transport to remote sites, and available in light colours and reflective finishes to reduce heat gain in summer. Sheeting may have recycled content (check with the manufacturer) and end of life recycling or reuse rates are high.
  
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