Flagship Green/Renewable Energy System.
- First green energy community owned complex in the Republic of Ireland.
- Wind Turbine Heat Pump and Solar panels.
- Eco Reed-bed Waste Management System.
- Monitoring and display of ongoing savings from renewable energy uptake.
- Comprehensively "green" energy designed building.
- Fully preserves environmental assets.
- Area has received approval under the EU Beatha Environmental Programme.
- Anchor feature of the Energy Trail Project.
Solar Power System.
There is an array of six one and half-square metre solar collectors installed on the roof. Each one delivers a nominal 1.5 wh to the hot water system, making 9kwh output in all. The system is circulated by a small photovoltaic panel and makes input into hot water cisterns above 35 degrees Celsius. It works on the sun's heat, which is reflected in each panel from a black matt background onto a series of collector tubes through which the heated water is being passed. The heated water is stored in cisterns in the plant room.
The centre will use a fair volume of hot water, having a sports facility, a gym, and a sauna and changing rooms with shower rooms.
The solar collectors make a contribution of between 40% and 60% to the building's required hot water budget. It is a closed system, augmented by the heat pump installation which background boosts the hot water store should the solar array and the turbine-input fail to bring the hot water temperature above 40 degrees Celsius. This temperature is about the maximum the human skin would tolerate in showering conditions. Thus the solar array is also integrated with the turbine generations along with the heat pump system
The wind turbine is a 6kwh machine, which produces electricity. This electric power is used via a resistance coil, just like an immersion heater to bring the hot water system up to 65 degrees Celsius whilst the turbine is driven. Above this temperature the turbine control switches the electric power over to convective hot air production which is delivered into 2 of the 5 zones, preventing the thermostats from returning a signal to the plant room calling for space heating from underflow, providing the conviective warm air conditioning is sufficient, ambiently.
The original renewable energy system design included the wind turbine installation to take advantage of the expected net-metering facility, which is looked for to come on line in this country within a short while. The task force committee is due to report to Minister Joe Jacob DPE with its recommendations on this and other matters in July 2000.
If or when the net metering becomes an option, the Dolmen Eco-Tourism centre will be able to export its generations straight into the grid. The output from the wind turbine will be metered at the point of grid connection. The grid will accept this generation (up to an agreed level) on a unit for unit basis a sap of k wh with no exchange of money being involved. Thus the electricity meter at the centre will be backed, so that the electricity consumption which we can not supply via other renewable systems, such as the required for the light, appliances and pump activation's will be paid for by the export of green electricity. The centre could there by become totally green energy powered. This remains a desired option for the future of the Dolmen centre
The Heat Pump
All space heating in the Dolmen centre is effected by renewable energy. The mainstay here is a heat pump system (loosely called a geothermal system). In fact it is a geothermal-solar system, and utilises the solar energy, which is banked in the earth one metre down; the earth temperature is always 7 to 8 degrees Celsius, a storage of the sun's continuous radiation of heat upon our planet.
This geothermal bank of solar energy is harvested by means of a chilled fluid loop (a collector) which is buried outside the building in an area of approximately 700 metres squared. The collector system consists of an array of 12 circuits 150 metres in length, each buried to an depth of 1 metre and brought back from the undefiled to a manifold chamber near the building. These loops feed into a single major flow 9and return) throughput into the plant room.
Here 3 heatpumps, or heat exchangers, deliver a nominal 15k wh of heat each to the building when called upon. This heat is brought into the building in cerements of 3 to 4 degrees Celsius. It is transferred from the collector loop which uses a glycol based refrigerant liquid,by means of the heat exchangers (each of three evaporator plates and hence delivered to a water matrix which is laid underfloor throughout the entire building in polypropylene piping.
The fluid in the interior matrix is water based and governed by sensors and activators. The building is zoned into 5 different areas, thermostatically controlled in the plant room. The water in the underfloor slab is always below 50 degrees celsius, generally in the low mid forties. This heats the entire floor slab to the required level. For example, a floor slab of about 20 to 21 degrees celsius will give an ambient temperature of about 18 to 19 degrees celsius.
The heat pump system is time controlled so that the maximum amount of useful heat is harvested at off peak rate between 11.00 pm and 8.00 GMT, when the tarrif is more like 50% of that during the day.
This heat pump system is also programmed to background boost the 1200 litre hot water system should the other renewable energy installations not furnish heat above 40 degrees celsius during the rest of the day (because of weather conditions).