Heating

The heating system is probably the detail we have spent most time researching. The house is designed to have a large roof towards south with room for solar panels and possible future solar cells.

I've spent weeks of spare time to find a solution that is energy efficient and cost effective, too. I will present the final solution first, followed by two solutions that were not implemented. One fell upon its exorbitance and the other was too expensive.

In Sweden, for plenty of good reasons, geothermal heating is very popular nowadays. Thanks to the cold climate, geothermal heating is probably the most effecient heating solution at our latitudes. Here, a geothermal heating system reduces the heating costs by two thirds and the investment payoff time is usually six to eight years. A known drawback is that the system takes heat out of the geothermal hole and the hole gets gradually colder causing reduced efficiency.

I also called the company Energy Advisory, jointly run by 26 cities in the Stockholm area. Here I did not get the answer I expected or wanted. They suggested walls 25% thicker than standard Swedish walls of 25 cms and heating with wood pellets. Wood pellets are quite popular in the countryside. Even if the solution is carbondioxide neutral, I assume that burning pellets would be more efficient and less poluting if run on a larger scale.

My belief is that the more geothermal holes that are bored, the more efficient use of electrically-based heating and the more all holes contribute to a larger solution where less or no CO2 gases are emitted.

I have followed a few discussion fora on the net regarding heating solutions with solar panels. Solar panels are a smart way of producing heat and hot water during the summer six months. However, in winter time, the contribution from solar panels is close to zero. One known problem with solar panels is that if a larger area of panels is installed, the system will produce to much heat when the sunlight is the most intensive and cooling or a swimming pool is required!

Finally, I found a manufacturer that produces a heat pump combining the good characteristics of geothermal heating and solar panels. There are some advantages with this solution. The best of all advantages is probably that the excess heat from the solar panels summer time is used to heat the geothermal hole, increasing the efficiency winter time. Other advantages are that we get heating and hot water for free four to five months a year as well as inexpensive and continuous heating the rest of the year, partly thanks to a heat recycling unit that takes heat from the outbound ventilation and inserts this heat in the loop from the heat pump, making a contrubution to the heating.

To make the best use of geothermal heating, floor heating is a requirement. Floor heating requires a lower distribution temperature than regular radiators. The heat from the heat pump sent to the floors directly, whereas radiators require a shunt to
boost the temparture from 30 to 75 degrees C.

In our former house we had a power consumption for the heating of the house and the garage and the hot water of approximately 24000 kWh annually. The new house, having an area almost twice the former house's, we have received a calculation stating a utilization of 7500 kWh/year, that is, more than six times more efficient!

I have also had a look at C l i m a t e w e l l 's heat exchanger, but it was too expensive. This company has solutions based on a substance, probably some sort of salt, that melts and freezes. At transitions from freezing to floating, enormous amounts of heat must be supplied. When melting, huge amounts of heat are induced. This leads to significantly larger heat capacitivity [kJ/(kg*K)] than water, for instance.

Another crazy idea was to try to construct a completely closed and extremely well insulated water tank of 175 m³. Having such a tank, we would probably be self-supplying on heat and hot water, excluding the power required to run the heat pumps. The solution would hardly be payed off and we would never
be granted a build permit for such a thing.