all the earth in contact with parts of the building structure, for example 
As geostructures are those which foundation elements of a building, to improve the viability of a poor foundation soil are needed.
for supporting and building the Green
geostructures training required of all sizes can be equipped with heat exchangers. Those with the substrate in contact concrete piles and concrete walls labeled with plastic pipes to exchange heat or cold
of the ground. These lines are then combined to one or more heat pumps supplied. The operation of the plant is based on an annual cycle in which during the heating season, the underground heat (cold entry into the ground) and during the cooling period is extracted from cold (heat). The advantages of such a system manifest themselves in reduced operating costs due to the way
case of fossil fuels (80%) and in a reduction of CO 2 - emission (45% to 100%)
energy piles
Reinforced concrete piles usually have a diameter between 0.4 and 1.5 m and a length of several meters to over 30 m. According to the pile diameter on the inside usually a double or quadruple U-tube or a pipe network of polyethylene is introduced. These tubes are completely surrounded with concrete to a good produce thermal contact. In this closed loop between the pipes in the posts and the
heat pump circulates a heat transfer fluid to heat or cold to the base exchange.
created this simple and appropriate technology is not excessive additional costs, but must from the outset with respect to the project plan included construction and energy concept be. At present there are in Switzerland about 30 installations of energy geostructures. Dock Midfield Airport Zurich
Subjects example midfield dock where our office in the planning and execution was involved wants to show I like the energy pile system works and what to consider
. project description
The Dock Midfield is a new reception and the terminal for 26 aircraft on the Zurich Airport. The 500 m long and 30 m wide building is on foundation piles which are used for energy.
Technical aspects
The Dock Midfield had to be founded on piles due to poor subsoil. There are 441 piles standing at 0.9 to 1.5 m diameter is required. This goes back to the ground moraine, which lies at a depth of 30 meters. Bearing on this moraine is the entire building. The piles had to be created with support tubes, which were withdrawn during the filling with local concrete. D
he ground is saturated almost to ground level with groundwater, which is due to the
small permeability of the soil (tonigsiltige deposits) is very practical standing. 3 10 of the piles were equipped with plastic tube loops, that is equipped as energy piles. The reinforcing cages PE pipes were installed, in which circulates a heat transfer medium.
Through these pipes a cooled respectively heated liquid (water-glycol) is pumped, which can heat the ground to be withdrawn or fed. This "heat exchanger", the soil be used under the Dock Midfield as seasonal storage.
The energy stakes are a long-term secure source of energy dar.
construction of the energy piles
With a detailed planning, the use of experiences of other projects with energy piles and close cooperation with entrepreneurs could be greatly simplified the construction process.
enabled the prefabrication of the pile deposits of high quality and avoided scheduling problems in the construction of power poles in a very tight time frame.
research project
could hardly fall back on operating experience for this innovative system. To plan and optimize secure and to a project with financial support from the Federal Office of Energy (BFE) was performed. In collaboration with the ETH Lausanne
detailed simulations and a response test using two probes were carried out on site. Thus, the thermal conductivity of soil measured in situ.
Energetic aspects
Income the energy piles was simulated by the ETH Lausanne (EPFL). The basis for this simulation were the pile plan, the hourly calculation of energy demand due to a thermal simulation of the building in cooperation with EMPA and the geological study by Jäckli AG. In winter, according to calculations from the ground in 1100 MWh of heat can be obtained. This heat is stored partly in the summer heat, which otherwise has to be dissipated with cooling machines (about 470 MWh). The rest of the Dock Midfield district heating is very small (about 420 MWh per year). The annual demand for electricity has not changed much, the power consumption of the heat pump in winter by savings in the summer (cooling on the energy piles) such as
compensated. With the energy pile system in the Dock Midfield, the required stabilization of the energy consumption of the entire airport is supported.
The energy stakes are a voluntary measure for an environmentally friendly airport. The energy stakes a building permit, which can almost be described as zero-energy house and use for heating and cooling most regenerable energy.
summer (cooling capacity)
The internal heat is removed from the building with the rooms and ventilation systems gathered over the recirculation cooling system. This waste heat in summer in the baggage sorting and year-round in transformer rooms, in the drive areas of passenger transport system and in other technical areas. In summer, this excess heat is dissipated directly to the energy piles to the soil. The refrigeration required for cooling the internal heat can be almost completely straight with the
power poles and in the heating season with are heat recovery (HR) covered. Only for a few tips, it is necessary to use the existing heat pump for winter as
refrigerator. This mode is also the safety (of Redunanz
cooling). It can be expected about 470 MWh per year cold generated directly with the poles, only about 10 MWh are yet to meet with the chiller. In the other with the power poles, the rooms in the basement, particularly the baggage-Vo
rsortierung, cooled directly through the uninsulated floor of course. would have no power poles with a slow rise in global temperatures in these areas are expected. In this area as the recirculating cooling units
and the corresponding demand for energy can be saved, which can be estimated at about 300 MWh cold. The cold supply air for about 18 - 20 ° C (cooling coil in the mono block) in the summer is created with separate chillers.
transition
with free-cooling internal heat could also be made of the existing cooling towers on the roof to the outside air. According Simulations, this mode not be necessary. winter (heat demand) in winter is primarily used to heat the internal heat recovery (690 MWh). For this, the heat pump that cools the circulating cooling system. If additional heat demand the floor, the stored heat is withdrawn (1100 MWh), this is also the same heat pump used. It can deliver up to 630 kW useful heat. This is not sufficient (very cold winter days), the terminal covers to the airport district heating network the missing heat capacity demand. Thus, in winter the heat requirements of the building are covered mainly with internal waste heat and geothermal energy. The heat
pump with a COP of 4 provides total 2360 MWh of useful heat to about 40 ° C. 420 MWh heat from district heating still be obtained to meet peak demand.
costs
The annual costs are lower due to energy piles to about CHF 16'000 .-. With the energy pile system, renewable energy can be used in an economical way.
The total investment for the power poles is about Fri contrast, 1.1 million could be saved .- Fri 130,000 (about 600kW smaller heat supply, in the basement sorting less air circulation devices).
The additional investment is therefore Fri 970'000 .-. annually reduce the energy costs by about CHF 94'000 .-; the stand n by CHF 11 ' 000th - higher maintenance costs compared.
Assuming that 30 years amortization period and 5.5% interest rate, so bring the energy piles up an annual profit of about 16,000 .-. Fri Unlike expected, this additional investment through energy savings within 12 years be repaid (without interest).
These calculations were performed with the energy prices of the unique (Fri 80.-/MWh heat, electricity 166.-/MWh Fri). The results can change dramatically with changing energy prices. The current situation with lower electricity rates and rather high gas and oil prices improved the profitability of the energy stakes considerably.
Conclusion
The first results show the data that the heat extraction works well from the ground. The heat pump, one of the largest in Switzerland, is running in cold weather almost constantly. It works very efficiently and thereby achieve a high level point of about four, that is, from an energy unit of electricity generated, four units of heating energy. The energy output of the heat pump exceeds expectations, improving the economic viability. The cooling in the summer to work properly, as the past summer have shown below-the-century summer of 2003. The detailed analysis of the data will allow Unique to optimize the operation of the plant further. For the development of other energy projects such valuable data is available to assist in the planning and calculation can draw on previous experience.
Links:
www.hakagerodur.ch www.geothermal-energy.ch
Urs Balmer
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