SunFlow® Eco House
Situated on the outskirts of Mosgiel, the SunFlow® Eco House is designed to highlight the integrated heating solutions offered by Warm and Cool, as agents for SunFlow® infloor heating systems from Heating Partners Ltd - www.sunflow.co.nz
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This and similar central heating designs will provide incredible comfort
and save you $1,000's over the years of operation.
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See the actual energy use compared to normal expectations below
The 150mm floor slab sits over 70mm of polystyrene and contains a SunFlow® hot water pipe system providing the owner with up to 224m2 of infloor central heating. Currently 160m2 of the floor is operating as unoccupied bedroom areas are not needed. Heated water is supplied to this system in multiple ways...
Solar Collection
In front of the house is a set of 5 Conergy Black Chrome flat plate solar collectors, with a capture area of 11.65m2. For the advantages of the Black Chrome flat plate collectors, see our Hot Water page. Initial solar gain is provided to the domestic hot water cylinder which is heated very quickly due to the large collector area. Additional solar gain is then diverted to two 20 tonne concrete storage blocks to be held for future use.
From October to April, excess daily solar hot water production is directed to storage to be used when solar gains are low - this reduces the inputs required from the heat pump. From May to September, any excess solar gain goes directly to the floor.
[The panels are set at a 44° pitch, facing almost due north]
www.conergy.com.au www.conergy.com (world-wide)
Solar Storage
Two 20 tonne concrete storage blocks sit beneath the house floor slab. These blocks are fully insulated from the surrounding ground and contain floor heating pipe in multiple layers which enables solar heated water to be retained for later use. When the heating system calls for input the first priority is given to this stored hot water.
Hot Water Heat Pump (Aerothermal)
When the solar stored water has been used or is not available, a high efficiency hot water heat pump begins to meet demand from the heating system. This heat pump can deliver up to 18 kilowatts of heat using just 4.7 kilowatts of electricity - see our Aerothermal Page.
www.bdt.co.nz (Mitsubishi Electric New Zealand) 
Domestic Hot Water (not connected to the heat pump at present)
This home uses a high quality, mains pressure, stainless steel cylinder manufactured to standards not achievable in New Zealand, that carries a full 10 year warranty. See our Hot Water page. This cylinder contains two internal heat exchange coils that receive hot water either directly from the solar system, or from the hot water heat pump. When the sun shines domestic hot water is virtually free and if the heat pump is used the cost is only 25-30% of the standard electricity rates.
Eco-Lighting
The SunFlow Eco House also uses low wattage LED down lighting in high use areas and other areas make use of sensor switches to ensure that the lights are only used when necessary and that they turn off automatically. Read more...
Shoulder-season heating (not fitted to the SunFlow Eco-house)
Many of the floors in our centrally heated homes are not operated by their owners from October to April. In our newer homes we have fitted a high capacity fan-assisted radiator (5.3, 7.1, or 10 kilowatts) which is also operated via the hot water heat pump.
- These units enable fast, easy heating even when the main floor system is not operating - and you get a similar high efficiency and low operating cost to standard air heat pumps.
- By using a water heat pump there is also the added bonus of providing cooling to your home in summer at the flick of a switch.
Actual Energy Use
This home uses Genesis : Household Night and Household Day Plan www.genesisenergy.co.nz
- The Eco-house heating systems currently use only night rate power
- Current Household Night Rate : 11.0 cents / kilowatt (incl GST, before prompt payment discount)
- The home is permanently occupied by 2 adults
Actual Energy Use For Central Heating and Domestic Hot Water Heating 2011
(figures include GST)
| Mar 2011 | Apr 2011 | May 2011 | Jun 2011 | Jul 2011 | Aug 2011 | Sep 2011 | Oct 2011 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| kw | Cost | kw | Cost | kw | Cost | kw | Cost | kw | Cost | kw | Cost | kw | Cost | kw | Cost | |
| Heat Pump1 | 56 | $6.16 | 182 | $20.02 | 363 | $39.93 | 595 | $65.45 | 732 | $80.52 | 1128 | $124.08 | 867 | $95.37 | 678 | $74.58 |
| Hot Water2 | 35 | $3.85 | 58 | $6.38 | 58 | $6.38 | 54 | $5.94 | 51 | $5.61 | 64 | $7.04 | 42 | $4.62 | 21 | 2.31 |
| Total | 91 | $10.01 | 240 | $26.40 | 371 | $46.31 | 649 | $71.39 | 783 | $86.13 | 1192 | $131.12 | 909 | $99.99 | 699 | $76.89 |
| Per Day | Per Day | Per Day | Per Day | Per Day | Per Day | Per Day | Per Day |
|||||||||
| Floor | 19.9 cents | 66.7 cents | $1.29 | $2.18 | $2.60 | $4.00 | $3.18 | $2.41 | ||||||||
| Hot Water | 12.4 cents | 21.3 cents | 21.3 cents | 19.8 cents | 18.1 cents | 22.7 cents | 15.4 cents | 7.5 cents | ||||||||
| Temp (Out)# | 14.7°C | 12.9°C | 11.0°C | 6.0°C | 6.7°C | 5.6°C | 9.3°C | 10.9°C | ||||||||
| Temp (In) | 22°C | 22°C | 22°C | 21°C | 21°C | 21°C | 21°C | 21°C | ||||||||
1. The heat pump currently operates solely on night rate power.
2. Hot water cylinder is not currently connected to the heat pump - solar and element heating only (night rate).
# NIWA monthly summary figures - Dunedin Airport (Taieri)
Average weekly heating cost = $14.46 (to date)
Average weekly hotwater cost = $1.20 (to date)
