Objetivo The original design, based on two patents of SOLTEC, was to build a greenhouse that in Winter produced surplus energy during daytime, which could be stored in a pebble bed rock heat storage (air system). At night the heat is recovered from the pebble bed by circulating air through it and into the greenhouse.The aim was to reduce the fuel consumption in a greenhouse used for pot plants. The problem was approached in two stages:- replacement of an existing greenhouse's single glazing by double layer polymetacrilate 8 mm thick- installation of solar air collectors and a pebble bed heat store.(36 air collectors with a total collecting area of 40 m2).Before changing from single glazing to double glazing and installing the solar plant, the greenhouse consumed some 6 000 kg/yr of light fuel. After the change the consumption dropped to only 700 kg/yr. Including the electrical consumption of the solar installation and the pebble bed heat store the break down in fuel equivalent is:6 000 - 700 (+ 3 000 Kwh electric); 6 000 - 700 - 900 = 4 400 kg fuel or 73% savings. Frost protection was ensured and the benefit in Winter of higher temperatures in the greenhouse led to quicker growth of the plants.The cost for heating the greenhouse has been reduced from 3 000 000 to 650 000 Lit.per year (1982 prices).No repairs were made in the first two years of operation.The solar installation is fully automatic and no man-power is required for its supervision.The theoretical forecasts (auxiliary heating required in December and January only) are fully confirmed by practical service.The greenhouse can be kept at night temperatures higher than16 deg C many months of the year thereby increasing its productivity.In Summer the solar installation is used to warm water for irrigation.The construction of greenhouses with regard to energy savings nevertheless has to be reconsidered in general. The thermal losses through the metallic frames are too high. The control of greenhouse microclimates has to be improved and should include soil and air temperature, air humidity and CO2. This system shows promise for solar energy applications in horticulture.The 170 m2 greenhouse was insulated by replacing the single glazing with double layer polymetacrilate thereby reducing the heat conduction from 2.4 to 1.3 KW deg. C. This, together with the addition of 40 m2 of air collectors resulted in the greenhouse collecting more energy than was required during daylight hours. Two insulated storage beds were therefore installed below the collectors; one operating at relatively high temperatures (10m3) and the second for lower temperature heat storage (20m3). Their heat capacities were designed to be 135 and 80 KWh respectively.In the Summer, heat not required is either stored in the two pebble beds or used to preheat the greenhouse irrigation water whilst in the Winter all the excess heat is stored for use during the nightime when normally fuel oil was required. Associated equipment is made up of:- air ducts, valves and fans- air-water heat exchanger- electrical controls. Programa(s) ENG-ENALT 1C - Programme (EEC) of financial support for projects to exploit alternative energy sources, 1979-1984 Tema(s) 3.1 - THERMAL Convocatoria de propuestas Data not available Régimen de financiación DEM - Demonstration contracts Coordinador Azienda Floreale Diem Aportación de la UE Sin datos Dirección Via Oberto Doria 23 18030 Camporosso Italia Ver en el mapa Coste total Sin datos
