Your choices:
1 Sunshine; 2 Comfortable indoor climate; 3 Local heating (ind. house)
| What is your resource? | What do you want to deliver? | What is the service the customer wants? |
| Biomass (digestible sludge) | District cooling | 2 Comfortable indoor climate |
| Biomass (fermentable sludge) | District heating | Electricity |
| Biomass (solid) | Electricity | Process cooling (< 0 °C) |
| Geothermal | Fuel: Gaseous | Process heat/steam (50 - 150 °C) |
| 1 Sunshine | Fuel: Liquid | Process heat (150 - 1000 °C) |
| Water | Fuel: Solid | Process heat (> 1000 °C) |
| Wind | Local cooling (ind. house) | Transport |
| Residual oils/fats etc | 3 Local heating (ind. house) |
The characteristic for single family houses is that the variations in energy need may be very different from hour to hour. For example will the fact that one person in the household takes a shower suddenly demand a rise in heat supply to the hot water system and if windows are opened for intensive ventilation the demand for heating suddenly increases radically. Also the opposite is true: A party with 20 participants will suddenly increase the heat supply to the house with about 2-3 kW (one person releases approximately 100 W only in the form of body heat and if they are dancing the heat release increases) and there might suddenly be a demand for cooling!
Central heating in single-family houses can be water-borne – which is preferred in case of solar heating – or it may be air-borne.
With water-borne systems, the solar collectors should be complemented with an accumulator tank to even out thermal load. The accumulator tank shall be large enough to cover the average heat demand of the house, tap water and heat combined, during 24 hours with a temperature drop of about 20 °C. With an accumulator tank integrated in the system it is simple also to integrate a top-up heating system (e.g. pellet-fired) by a separate heat exchanger coil in the accumulator. Especially in the case of simple flat-plate solar collectors, this will be necessary to guarantee the sanitary quality of the tap water.
In case cooling is needed in a single-family house, this is usually arranged by installing separate AC-units in the rooms where the need is most pronounced, or to have a mobile AC-unit that is moved to the room where it is needed. For single houses only compressor cooling machines are applicable. In case the building is equipped with solar cells and in case the solar cell array is equipped with an inverter so that the solar cell electricity is fed into the internal 230 V electricity net, then will the electricity produced by the solar cells contribute to maintain a comfortable indoor climate – when the sun shines. However, and due to the low efficiency with commercial solar cells and to the "dilute" nature of solar radiation – except special conditions – the electricity produced from solar cell arrays is usually not near the demands for indoor climate control.