Hello again @nort1 and my thoughts for @Dilemma ,
My latest build is combination of SIPs construction and 70mm framing with a 70 polystyrene overlay giving R4.3. walls and R5.2 roof.
Being in the North Island, the cost benefit of triple glazing is not warranted so double glazing is specified.
The heating requirement is for a constant 22oC every day in every room, so a ducted central heating system seemed to be the obvious choice.
I investigated these heating options:
I started out with what I thought was the most cost-effective running cost – natural gas.
Capital cost for the smallest Braemar 14kW plus ducting $14,000 – acceptable.
Before that build commenced we sold the section and developed another that did not have natural gas.
We now had to consider a ducted Twin heat pump system. Running costs slightly better than NG but a capital cost of $17500 and higher maintenance costs – rejected - well over budget.
As I do not have the inclination to cut stack and dry firewood or have a ‘free’ supply, I rejected Wood Fires and Wood fired Boiler systems. All seemed to give gave uneven heat, difficult transfer systems and slow start up times, as well as sort in the house – the capital cost was well beyond budget even if the fuel was ‘free’.
The next consideration was a pair of pellet burners situated at either end of the house with twin heat transfer units to both lower and upper stories. Running cost higher that for NG or Heat pumps but a capital cost of $9500 – I could run for 15 years before the extra fuel cost balanced to almost double the capital cost. I almost purchased until I found what I now consider to be the best heating source for my needs.
FAR Infrared heating - DO NOT CONFUSE FAR’ WAVE LENGTH with SHORT WAVE INFRARED LENGTH -.
The only safe wave length from the Sun is Far Infrared and is essential to animal life.
Very little if any comparative information is offered by Government Agencies or Consumer. Only two suppliers to NZ that I have found – Herschel and Infrared Panels NZ.
Herschel are about three times the cost of the panels from Infraredpanels and as the components appear to be identical from the top manufacturer in China, and merely assembled in Germany and badged Herschel, I concentrated on checking out Infraredpanels NZ.
I was very surprised - for my very well insulated house, the running cost came in only about 1.3 times the kW cost of a COP 3 Heat Pump.
The FAR Infrared waves heat the whole of the fabric, walls, furniture and humans in the room – the absorbed rays penetrate human skin and bone to a depth of up to 75mm and reflect off surfaces not in direct sight line of the heating panel. This continues until the room is heated to a balanced 22oC. Obviously, it takes a few days until every room in the house is balanced and then every surface re-radiating off at 22oC. From then on, it requires only a maintenance kW boost controlled by thermostat to cover exterior temperature changes. When you open the door, very little heat escapes as there is no connected air circulated heat.
A Heat Pump works on distributing warm air by convection with very little re-radiation, so as soon as you open the door, the warm air escapes. A typical gradient measure is 26oC at ceiling, 22oC at head height and 16oC at floor level – and 12oC when you leave the door open!
But I was most surprised at the capital cost. Herschel came in at $10500 and Infraredpanels at $4500. With an effective running cost of 1.5 times a Heat pump this is a ‘no brainer’ for me, so I wondered why the sad lack of knowledge in NZ.
It seems that the Heat Pump market dominates all discussion, trade and consumer knowledge here, but in the EU the opposite is true – very few heat pumps are sold in comparison with FAR Infrared panels. But even better is the long-term maintenance costs. Some Heat Pumps last only 15 years with costly 5 yearly maintenance whereas FAR Infrared Panels last a lifetime with NO maintenance.
Maybe you might re-consider your heating systems in the light of this information?
All the best