Construction Systems
SOURCE AND USE OF MATERIALS
There are two types of construction systems. Heavyweight and lightweight. An example of heavyweight would be concrete, brick or tile. Lightweight would be timber or lightweight steel.
The mass content of systems both heavyweight and lightweight have different thermal performance and environmental impact.
These differences will depend on whether they are used internally or externally, the local climate, transportation costs, site requirements and exposure to nature.
Environmental impact for similar materials can be different depending on their source. There is no perfect system. It should be a compromise that takes advantage of the best possible combination of materials for a particular job. A mix of heavyweight and lightweight systems usually produces the best economic and environmental outcome.
Heavyweight Construction:
- Although the cost of creating the materials for this is greater, the system decreases operating costs when used with designs that take advantage of passive heating and cooling.
- The benefits should be weighed in comparison to site impact and disturbances and transportation costs.
- Is most appropriate in climates with high diurnal (day-night) temperature ranges and significant heating and cooling requirements.
Lightweight Construction:
- Generally has lower embodied energy.
- Can yield lower total life cycle energy use, particularly where the diurnal range is low.
- Responds rapidly to temperature changes and can provide significant benefits in warmer climates by cooling rapidly at night.
- Is preferred on remote sites with high materials transportation component.
- Usually requires more heating and cooling energy in cold to warm climates (where solar access is achievable) when compared to heavyweight construction with similar levels of insulation and passive design.
- Can have low production impact (e.g. sustainably sourced timber) or high impact (unsustainably sourced timber or metal frame).
- High mass lower level and low mass upper levels are combined to optimise use of embodied and operational energy.
- Every site and design decision must be made keeping in mind the best possible outcome for that job.
- A combination of internal heavyweight and external lightweight systems is optimum for energy use.
- In moderate climates where heating and cooling needs are minimal, the cost of producing heavyweight systems does not justify their use since the benefits are not needed.
- Where solar access is unachievable or undesirable insulated lightweight construction is often more efficient as it responds quickly to mechanical heating or cooling.
MAINTENANCE
- Compared to other finishes, brick veneer requires minimal maintenance.
- Well maintained lightweight systems have durability equivalent to heavyweight systems.
- Reduced life span of a building system which is the result of poor maintenance negates any savings that were expected.
- Consider the realistic expectations of long term maintenance when choosing the exterior cladding of your home.