By Andy Yeomans (from his presentation at the W.E.D Festival June 7 2015)
Whilst renewable power generation and storage are rapidly becoming cheaper in dollar terms, they still require significant resources. We should not be wasting any resource so energy efficiency is still very important.
Two main aspects of this are:
Lighting & Appliance Efficiency and
Passive Solar Design or what I prefer to think of as ‘working with nature for building comfort’.
Most of you probably have some awareness of appliance efficiency.
With lighting, halogen is marginally better than the old globe, florescent much better and LED by far the best and getting better.
An additional advantage of LEDs is that:- Downlights often negate roof insulation by allowing very draughty gaps in the ceiling. These are required to avoid fires starting from the heat of inefficient lights. Since they produce much less heat, LEDs can be more easily capped to prevent draughts.
Living in a stand alone, solar powered home for over 30 years I’ve become good at understanding appliance labels and selecting the most efficient, not necessarily the cheapest.
The star system can be confusing. With advances in efficiency, 4 stars today may be tomorrows 2.5 star when the scale is changed. The star label also has an estimated kWhr/yr figure which allows more reliable comparison.
The fridge using 400kWhr/yr may be $100 less than the more efficient 300kWhr/yr one, But the greater efficiency will save you that $ 100 in under three years.
Many people have become lazy in the past days of cheap power. We now know that fossil fuels are far from cheap when their impact on our environment is considered. Even Renewable energy still requires resources to harness it.
So, last but certainly not least. If you’re not using it turn it off!
In the home, probably the most cost effective device for this is awareness linked to a finger. For large buildings, power management systems can include master switches to turn off all but emergency lighting and essential equipment.
The second main aspect of home or building design, passive solar or working with the environment, is often ignored.
If we consider the suns daily path at all seasons. Ideally a building will have its longer side facing North with living or office areas on that side. On the northern side eaves or shading can be designed to keep out Summer sun but allow the lower, Winter sun in for warmth.
Wall and especially window areas facing East or West are minimised to avoid heating in the low morning or especially afternoon summer sun.
Winter sun entering can be absorbed by a slab floor or high mass wall storing heat for night-time. The same thermal mass will also soak up the peaks of summer heat. Many Australian homes are still built inside out, bricks outside, insulation and lining inside. If the bricks or similar material are inside they will moderate temperatures by taking up or emitting heat whilst the insulation and outside lining controls the outside temperature and weather effects.
Even if your home does not face north or is uninsulated all is not lost. There are many low, and high tech ways to retrofit ‘solar and heat control’ : Reflective paint on exposed surfaces, Shading – Built or Grown. Deciduous trees can give natural shade control. Preventing unwanted heat reaching a wall or window is far more effective than blocking once its inside.
I’ve noticed that most buildings, even in the country face the road. I recently rang Council and was told that whilst there is no planning rule dictating this, buildings must fit in with the street-scape.
I imagined a new street with all homes facing N at the same funky angle to the street. Better still that the solar aspect of new building blocks should be considered when subdividing.
We can also work with prevailing breezes. For instance, a well placed screen or hedge can be used to deflect a breeze through or away from a window or door.
Insulation controls movement of heat. Roof insulation is a number one consideration. A large amount of heat may be lost, or in Summer gained, via the roof. Roof insulation is often easy to retrofit.
Wall insulation is also valuable, especially on sides exposed to heat or cold winds.
Under floor insulation and double glazing may also pay, especially in a new home. In our milder, coastal climate it would be of low importance but inland at say Uki or Tyalgum where temperatures are known to range from minus 8 to over 40C they are well worth considering.
In older homes especially, gaps or drafts can defeat even the best insulation. Like having a hole in a warm coat.
With the best, well sealed, energy efficient homes, air to air heat exchangers are used gaining fresh air with minimal loss of heat.
So, I have very briefly covered the basics of energy efficiency in buildings.
Many people have an ingrained idea of energy and material saving impacting negatively on their lifestyle.
A well designed energy efficient building is actually more comfortable than a standard one. The 10-15% extra cost to build is usually recouped in the first five years or so of running costs.
My most important message, gained from experience, is that efficiency in the use of any material or energy is nearly always repaid with a winning situation for your wallet, comfort and our natural environment.