Cooling was an easy decision. Installing ducted air conditioning might seem counterintuitive for an off-grid, energy efficient house, but one of the learnings from the shed is that there is a lot of excess energy available in summer. When you do the numbers, it works easily. Depending on our final system sizing, it might not work 24/7, but it should be OK all day. And with a good energy house rating, it shouldn’t warm up too much overnight. Luxury. No compromise. No bill.
We didn’t want evaporative cooling even though its low power – not so good on humid days, uses water, but most importantly, it can be problematic for bushfires.
If embers enter the cooler, the cooling pads can catch fire, you’ve got a fire on your roof, and your house is compromised. For BAL 12.5 -29, evaporative coolers can be used with protective measures, such as screening, or non-combustible butterfly closers and sealed to the roof to prevent gaps. Higher BAL levels need special permits. So even though they’re allowed, it just didn’t seem like a good idea to introduce a fire risk to the roof.
Our builder’s standard design incorporated reverse cycle ducted air conditioning so we decided to leave this in the build, with just a few tweaks.
For our house size, their standard inclusion was a 3 phase Daiken reverse cycle ducted air conditioner. 3 phase power adds a lot of cost to the solar system – inverters required for each phase. So we reduced the size of the AC unit to the largest one that Daiken made that was single phase, but upgraded it the premium inverter model. We won’t need to be cooling the entire house at the same time, and can easily shut off individual rooms with the zone control system.
We have added the insurance policy of having ceiling fans in the bedrooms.