Eficiencia Energética | Energy Efficiency FuturEnergy | Mayo May 2016 www.futurenergyweb.es 69 en sus supermercados, habiendo logrado muy buenos resultados en superficies emblemáticas como la de Oñate (Guipúzcoa), donde se testearon y verificaron. Posteriormente se implementaron las soluciones tecnológicas en el resto de los establecimientos, cuando el coste y el retorno de la inversión así lo hacían posible. Algunas de estas medidas son únicamente válidas para supermercados de nueva creación, y la idea fundamental de ZEROSTORE es que el modelo sea válido para la rehabilitación energética de los centros que están ya funcionando, muchos desde hace varios años. Esto es sin duda más complicado, dado que es necesario estudiar la complementariedad con las instalaciones existentes y valorar que la implementación de las mejoras no afecte a la buena marcha y a la actividad comercial del establecimiento. En el caso concreto del supermercado de Vitoria se plantearon varias mejoras: cerrar los muebles murales de alimentos refrigerados y congelados (Fig. 2), mejorar la envolvente térmica mediante una doble puerta en la entrada que minimice las infiltraciones de aire durante el trasiego de clientes, evitando las cortinas de aire con alto consumo eléctrico (Fig. 3). También se ha acometido la rehabilitación de la cubierta introduciendo claraboyas con alto grado de refracción para la provisión de luz diurna, convenientemente distribuida, combinada con iluminación LED y modulada en función de la disponibilidad de luz natural (Fig. 4). La comparativa de consumos entre los años 2014 y 2015 demostró que este sistema suponía un ahorro de entre un 20 y un 30% del consumo eléctrico en iluminación. (Fig. 5) In the specific case of the Vitoria supermarket several improvements were proposed: closing in the refrigerated and frozen food wall cabinets (Fig. 2), improving the thermal envelope by means of a double door in the entrance to minimise drafts as customers come and go, as well as avoiding air curtains that have a high level of electricity consumption (Fig. 3). Roof refurbishment also took place by introducing skylights with a high level of refraction to provide suitably distributed daylight, combined with LED lighting that is regulated depending on the availability of natural light (Fig. 4). A consumption comparison between 2014 and 2015 demonstrates that the system saved between 20% and 30% on the electricity consumed by lighting (Fig. 5). CCHP system With demand reduced, a CCHP system is proposed for the supply of power, heating and cooling from biomass, which can be integrated into the supermarket’s energy systems and housed outside the establishment, thus making its installation easier. The operation of the CCHP system can be summarised as follows (Fig. 6): • The primary energy source is biomass. A 250 kWt capacity boiler manufactured by LSolé, burns wood chips that are supplied from a silo situated next to the supermarket’s loading bay, to obtain high temperature heat. This heat is transferred from the boiler to a CHP unit by means of a thermal oil circuit. • The cogeneration unit is based on ORC technology (Organic Rankine Cycle) to transform high temperature heat into electrical power, obtaining low temperature heat as a byproduct. The unit developed by Rank for the ZEROSTORE project features cogeneration with two operating modes: one that maximises performance and has a thermal level of residual heat below 50ºC (that can be used for HVAC in the supermarket and DHW production) and the other that has a lower output but increases the temperature of the residual heat. • As a result, the required temperature is achieved to activate an absorption chiller. These machines are capable of obtaining cooling from heat with minimal electricity consumption. The proposed machine produces cold water at 5ºC. This heat cannot be directly used by the wall cabinets or refrigerators in the supermarket, as the technologies existing to achieve a thermal level of under -10ºC requires the use of ammonia, which is not to be recommended in the case of a public establishment. Fig. 2. Armarios murales cerrados | Fig. 2. Closed-in wall cabinets Fig. 3. Eliminación de cortinas de aire e instalación de doble carpintería en la entrada | Fig. 3. Elimination of air curtains and the installation of double carpentry in the entrance Fig. 4. Lucernarios en cubierta combinados con iluminación LED regulada Fig. 4. Skylights combined with regulated LED lighting
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