Multi-head splits vs single-split systems

There’s some debate about whether the best configuration of split systems for multiple rooms is to have multiple single splits or to use multi-splits.

By Richard Keech  2018-06-18

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Multiple single-split systems can be an eye sore


Increasingly split systems are used to heat and cool entire homes – not just single rooms.  The default way that split systems are deployed is what I call single splits – one outdoor unit piped to one indoor unit.  And repeat that configuration for each conditioned room.

The alternative, available from many vendors, is a multi-split. This configuration involves more than one ‘head’ unit for each outside unit.  Often a whole home might be served with only one (larger) outdoor unit, and heads in all bedrooms and living spaces. Continue reading “Multi-head splits vs single-split systems”

Is thermal mass over rated?

Are concrete slabs the best floor for an efficient home?

By Richard Keech 2018-06-16

Thermal mass

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.

Continue reading “Is thermal mass over rated?”

A spreadsheet model for efficient electric homes

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

Continue reading “A spreadsheet model for efficient electric homes”

Tips for efficient homes

A person making a checklist in a notebook
Photo courtesy: Unsplash

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. Continue reading “Tips for efficient homes”

Avoiding common energy mistakes in a new build

By Richard Keech (May 2018)

Part 1

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).

Continue reading “Avoiding common energy mistakes in a new build”

Improving hot-water performance

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?

Continue reading “Improving hot-water performance”