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 -

This and similar central heating designs will provide incredible comfort and save you $1,000's over the years of operation. 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...

Eco House Schematic

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 ton 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.   | (world-wide)

Solar Storage

Two 20 ton 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.

Air to 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. (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.


LED Light

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.

Actual Energy Use

This home uses Genesis Energy: Household Night and Household Day Plan in the Dunedin area.

Actual Total Energy Cost 1/3/2011 - 28/2/2012

kw Cost Monthly Average Daily Average
Heat Pump 5,195 $493.53 $41.13 $1.35
Hot Water 430 $40.85 $3.40 $0.11
Total 5,625 $534.38 $44.53 $1.46

Actual Seasonal Cost Profile For Central Heating & Domestic Hot Water Heating

Figures include GST

  Heat Pump1 Hot Water Pump2 Total Per Day Temperature
  kw Cost kw Cost kw Cost Floor Hot Water Outside3 Inside
Mar 2011 56.0 $6.16 35.0 $3.85 91.0 $10.01 19.9 cents 12.4 cents 15°C 22°C
Apr 2011 182.0 $20.02 58.0 $6.38 240.0 $26.40 66.7 cents 21.3 cents 13°C 22°C
May 2011 363.0 $39.93 58.0 $6.38 421.0 $46.31 1.3 cents 21.3 cents 11°C 22°C
Jun 2011 595.0 $65.45 54.0 $5.94 649.0 $71.39 2.2 cents 19.8 cents 6°C 21°C
Jul 2011 732.0 $80.52 51.0 $5.61 783.0 $86.13 2.6 cents 18.1 cents 7°C 21°C
Aug 2011 1,128.0 $124.08 64.0 $7.04 1,192.0 $131.12 4.0 cents 22.7 cents 6°C 21°C
Sep 2011 867.0 $95.37 42.0 $4.62 909.0 $99.99 3.2 cents 15.4 cents 9°C 21°C
Oct 2011 678.0 $74.58 21.0 $2.31 699.0 $76.89 2.4 cents 7.5 cents 11°C 21°C
Nov 2011 296.0 $32.56 14.0 $1.54 310.0 $34.10 1.1 cents 5.1 cents 12°C 21°C
Dec 2011 99.0 $10.89 13.0 $1.43 112.0 $12.32 35.1 cents 4.6 cents 15°C 21°C
Jan 2012 67.0 $7.37 10.6 $1.17 77.6 $8.54 23.8 cents 3.4 cents 15°C 21°C
Feb 2012 131.0 $14.41 9.4 $1.03 140.4 $15.44 49.7 cents 3.6 cents 14°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).

  3. NIWA monthly summary figures - Dunedin Airport (Taieri)

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