Will your new home be:
- a) 5 star energy rated, or
- b) Energy efficient?
Contrary to popular belief, the two aren’t the same.
This article will discuss the new thinking that is needed regarding the critical role Thermal Insulation plays in true Sustainable Architecture.
Sustainable Architecture Pillar 3: Insulation
The purpose of Thermal Insulation in any building is to regulate the internal temperature by reducing unwanted heat transfer through radiation, convection and conduction.
The ability of insulation to resist heat transfer is measured in a unit known as the R-value – the higher the R-value, the better the insulation.
So why is a 5 star energy rated home not the same as an energy efficient home?
The current Energy Rating system
The Victorian Building Commission’s compulsory 5 Star (soon to be 6 star) Energy Rating program for new homes defines minimum standards that your insulation must meet.
While definitely a step in the right direction, meeting these minimum requirements does not equal energy efficiency.
The reason is that energy rating assessments in Victoria are performed pre-construction and so cannot take into account poor construction techniques. For example, poorly installed insulation batts that expose just 5% of ceiling area can translate to losses of up to 50% of insulation benefits.
As long as Victorian energy efficiency ratings are measured pre-construction they can never equate to actual energy efficiency post-construction.
Actual energy efficiency
Possibly the major reason that Australians have accepted energy inefficient homes is that poor energy performance hasn’t really mattered.
Germany has been leading the world in truly energy efficient, Passive Solar Design, for many years now not because it’s trendy, but because it’s necessary. With Germany’s extreme winter climate, poor insulation and construction can allow unwanted heat transfer, internal structural condensation, ice build up and potential building failure.
The majority of homes in Australia will never suffer building failure as a result of poor insulation because our more moderate climates forgive poor design and construction.
However, by the same token (if we continue in our ways ‘because we can’) then the majority of homes in Australia will also never enjoy the benefits of true energy efficiency – zero/minimal heating and cooling requirements and a clear conscience knowing that our houses are actively contributing every day to the sustainability of our planet.
To achieve that, we need new thinking that goes beyond current minimum standards.
New thinking…
If we are to obtain the true energy efficiency benefits of Passive Solar Design, then we need to adopt Passive Solar Design thinking.
Rather than asking ourselves ‘what is the minimum R-value insulation required to obtain a 5 star rating?’, we need to ask ourselves the question they ask:
This question changes the mindset of merely adding high R-value insulation in ceilings and external walls on a checklist to masterfully designing and detailing your dwelling such that no conductive air gap exists between any internal living space and the exterior.
In fact, so serious is this issue in Germany that infra-red sensors are used post-construction to detect even the smallest of air leaks – which are required by law to be rectified by the builder.
Sustainable Architecture Insulation: Conclusion
5 star energy rated homes may meet minimum Victorian government requirements but do not equal energy efficiency.
True energy efficiency can only be attained when careful attention is placed on treating and sealing the entire building envelope as one continuous, air-tight shell.
If we are to experience the benefits of true Passive Solar Design it will mean adopting new thinking that goes beyond current minimum requirements.
The next article in this series will focus on Pillar 4 of Sustainable Architecture: Windows.
CONSIDERING SUSTAINABLE ARCHITECTURE?Go beyond minimum requirements with Passive Solar Design!
Engage our sustainable Design + Build services today.
Postscript
The Australian Government Deparmtent of Climate Change and Energy Efficiency is planning to introduce new regulations for the existing housing market in 2011. They are planning to make it a requirement to provide information about energy, water and greenhouse performance to both house buyers and house renters. Further, studies in ACT where this is already a requirement, have shown that higher energy efficiency in homes translates in terms of higher market values.
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