Frequently Asked Questions

Some of my best clients are owner builders. If you have some technical ability and have worked with various tools, this is an excellent option that I often recommend.

We provide all the design layouts, materials, and phone support, along with the ability to hire any tools you may need for the installation. We've never had a problem with this method for our clients; if any issues arise, we always find a solution. No one takes more interest in your home build than you do.

I advocate this on many occasions. You get one chance to run the pipes in the slab during the build.

It's cheap to install and a great option to have down the track; the heat source can be installed many years after the house is completed.

For cooling, coupling to the ground might be acceptable, but certainly not for heating.

A ground temperature of say 13 degrees is a big difference from a heated water temperature of 40 degrees. The thermal capacity of the ground is effectively infinite relative to the house. You can never really heat the ground under the slab to store heat; it will be lost, resulting in wasted energy.

You must have a thermal break (insulation) between the concrete slab and the ground. All empirical evidence from around the world supports this fact; it's simple physics.

When waffle pods first appeared 30 years ago, they had an R-value of 2.0. This was quickly downgraded to R 1.0, and in recent years, further downgraded to R 0.5. New Zealand rates pods at an R-value of 0.2.

If I were building my home, I would not rely on waffle pods for an insulated concrete slab design. See our schematics for insulated slab design.

Yes, hydronic systems have a higher installation cost, but they offer significantly lower running costs.

It's silent, effective, and efficient, but also the best method for health and safety. No air is blown around the house, so airborne viruses cannot spread.

Ducted vents are rarely zoned well, if at all. Ducting often has little insulation sitting in an unconditioned ceiling space, and poor installation is common. Ducts are rarely cleaned and are often damaged by tradespeople working in the ceiling.

We are somewhat biased on this topic, having spent considerable time creating the best zoning system. However:

• If you want the most comfortable heating (and cooling) for your home, you need to zone.
• If you want the most economical running costs (better for the environment), you need to zone.
• If you want different temperatures for each room, you need to zone.
• If you would like to heat a bathroom outside the main heating season, you need to zone.
• If it's a holiday home or you travel often, remote access is a wonderful feature.

It's a common misconception that you should keep the heat on all winter, even if rooms don't need it or no one is home.

With well-insulated slabs, you feel the heat rising through the concrete within two hours, and most rooms warm up within 4 hours from a cold start. We always recommend having a "setback" temperature when the system is off to improve response time when heating is needed. This is considerably cheaper than leaving the system running 24/7.

Even uninsulated slabs are worth turning off if no one is home or rooms are unused. From my experience, you start to feel the heat within 2 hours on most occasions. I would never recommend turning off the system completely unless you are going away for extended periods.

The heating effect from electric radiant cables is identical to water pipes in the slab. It all comes down to running costs.

Solar PV is extremely unlikely to be large enough to heat an average home. A typical 5kW PV system might produce around 15kWh on a sunny winter day in Canberra. This would be lucky to heat a whole house for even an hour.

Electric in-slab cables can consume 100W per square meter per hour. A 200m² house could consume 20kWh per hour. Since most Australian states require you to consume PV power simultaneously to get the full benefit, this isn't viable for heating (which is mostly needed when the sun isn't shining).

We could easily install electric in-slab cable if we thought it was the best option, but experience shows that many homeowners with electric cable are unhappy with the running costs, even with solar PV.