Blog

Are concrete slabs the best floor for an efficient home?

By Richard Keech 2018-06-16

Figure 1: Thermal mass is a two-edged sword

Thermal mass equals efficiency?

The use of concrete slabs on ground is ubiquitous in contemporary Australian home construction. Conventional wisdom says this is a great thing for energy efficiency because of increased thermal mass.  There’s some truth to this.  However, I think the reality is not quite so simple.

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Here’s a way of estimating the benefits of solar, energy efficiency and batteries in a home.

By Richard Keech, 2018-06-06

I was commissioned by the developers at The Cape to created a spreadsheet model to help understand the effect of different factors in an efficient electric home.  This lets you ask questions like:

• How much money can I save by building a home to X stars?
• Am I better off adding more solar panels or making the home more efficient?
• What are my likely running costs if I have an X star home with Y kW of PV?
• Is it worth putting in a battery system?
• Is it possible to eliminate energy bills entirely

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Tips for homes that are energy-efficient, comfortable, carbon-neutral with low or zero energy bills

By Richard Keech  2018-05-19

Based on a talk given on Sustainable House Day 2017 at The Cape (Cape Paterson)

Scope excludes water efficiency and materials issues such as embodied energy. Much of this applies to both improving existing homes and new builds.

Caveat. This is not intended to be comprehensive or a structured introduction to the topic – simply my own perspective, in temperate southern Australia, on a few things that are of particular importance or interest to me. So apologies in advance if I fail to mention things that are, perhaps, already well-understood, outside my expertise, or simply overlooked.

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By Richard Keech (May 2018)

In the course of assessing many homes for energy efficiency, I’ve seen that even new homes exhibit problems in the basic build.  Here are a few ideas of things that are often overlooked. This list doesn’t include the many and varied mistakes that can be made in the basic design (floorplan, materials, orientation, shading etc).

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There’s lots to think about when considering high-efficiency hot water.

By Richard Keech, May 2018

Energy efficiency is using no more energy than you absolutely have to to achieve a good outcome.  This is very true for domestic hot-water systems which typically account for between 1/5 and 1/4 of a home’s total energy needs.

I’ve written previously about hot water ‘Hot Water, more than meets the eye‘. The essence of this was:

• Hot-water systems generally use a simple thermostat to keep water above 60C for biosafety (ie killing Legionella bacteria);
• Regulations in Australia now allow clever regulation such that water is kept at a lower temperature (say 50C) for much of the time, with a periodic (say weekly) boost to higher temperature for sterilisation;
• Solar hot water system owners often boost manually, which means they probably fail to meet minimum biosafety requirements;
• Legionella can sometimes grow in cold-water pipes in hot weather.

So what next?  How to reduce the energy you currently use heating your water?

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