Eco Cute for underfloor heating: 1/3 lower running costs

By Sabine Lobnig, Jul 18, 2012, 10:23 2 minute reading

Eco Cutes are a standard feature in the Japanese all-electric house concept. The CO2 water heaters can both cover sanitary hot water supply and the water needed for the underfloor heating. This combined usage enables running costs to be lowered by 1/3, say Japanese companies . The market research company Fuji Keizai forecasts growth for the market for home energy systems to reach €7 billion by 2020.

At the beginning of the month, the Japanese market research company Fuji Keizai published a report predicting the market for home energy systems (including heating, cooling and air-conditioning systems) would reach ¥7 trillion (~ €73.6 billion) by 2020, effectively doubling from 2011.

Eco Cute for underfloor heating

In underfloor heating, warm water is circulated through a series of heating pipes, generally laid in the floor at the time of building. These pipes form a continuous loop between two central manifolds. Each room has its own circuit of pipes and can be controlled so that the heat can be generated exactly where you want it. Underfloor heating can either be used as a main or as a complementary heating system.

Eco Cutes are particularly suited for use in underfloor heating as they have a good efficiency when it comes tothe heating of water and mostly use the cheaper night time energy, storing the heat and using it during daytime when energy is more expensive. This helps keeping running costs down.

Advantages of using Eco Cutes in underfloor heating are:
  • the Eco Cute can cover the entire hot water demand (including but not limited to hot water for the underfloor heating)
  • the running costs are low
  • they have a long product life
  • large rooms can be easily heated

Disadvantages of using Eco Cute in underfloor heating are:
  • the initial investment costs are higher than for electric underfloor heating -
  • regular maintenance is needed
  • frequent use impacts on product life, and replacement is expensive
  • in case of a technical defect, heating and hot water supply are interrupted

Both electric and water based underfloor heating systems are almost identical apart from the fact that one uses an electric heating cable while the other circulates heated water through a pipe. The electric underfloor heating is cheaper toinstall and needs less maintenance than the hot water underfloor heating, but the latter is more efficient and offers cheaper running costs.

Also, the fact that the water for underfloor heating is at a lower temperature than in a conventional water central heating (typically between 35-50°C rather than 60°C), makes it more suitable for use in combination with heat pumps or solar water heaters. The floor can be covered with hardwood flooring and wood laminates or carpet.

Eco Cute savings:running costs 1/3 lower

Taking the average yearly hot water consumption, with the hot water tap load calculated using IBEC-L mode (the recognised Japanese load standard), Mitsubishi compared an Eco Cute underfloor heating system heating 8h/day an 8 tatami (3.64m×3.64m) wide room, with the a gas powered system. The costs were calculated on the basis of Tokyo's gas and power company's (TEPCO's) rate from September 2008, and according to the results Eco Cute was 1/3 cheaper to run.


By Sabine Lobnig

Jul 18, 2012, 10:23

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