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B UILDING & M ANAGEMENT E LECTRICITY IN HOSPITALS : SOLUTIONS BASED ON ECONOMIES OF SCALE V OLUME 3 I SSUE 3 S EPTEMBER - D ECEMBER 2019 G. S ÁNCHEZ -B ARROSO , M. G ÓMEZ -C HAPARRO , M. J. C ARRETERO -A YUSO AND J. G ARCÍA -S ANZ -C ALCEDO (2019). B UILDING & M ANAGEMENT , 3(3): 12-16 Where: C is energy cost expressed in EUR, E is energy adquired expressed in MWh, and DMP is the daily market price of the energy expressed in EUR/MWh. A consumer association option allows a group of consumers to add their consumption and resources. As advantages, firstly, we can highlight association makes to reach the minimum annual consumption possible. Secondly, the group can negotiate a greater volume of energy in order to obtain prices that are more competitive. The main disadvantage is again the justification of guarantees before the system operator. On the one hand, swap is a funding option as the contracting parties exchange a variable energy price for a fixed one. In this case, a hospital would receive a certain volume of variable-cost energy for a period of time in exchange for a fixed price. The fixed price is determined based on predictions based on current future prices. Therefore, a cost balance showed in Equation (3) is carried out to satisfy the deficit part at the end of the period. Through swap there is a less significant variation in the cost to the consumer in the face of large variations in the daily price. It also implies a risk relative to forecasts, since it implies a penalty if the consumption is overcovered or undercovered. On the one hand, integration of the architectural design and the building installations is proposed as an option that can generate an almost zero energy building, however, are strategic decisions taken before the construction of the same [20]. On the other hand, the prediction of energy consumption is a complementary tool for making supply decisions and developing energy efficiency measures, so there are works that apply artificial intelligence to the prediction of energy consumption [21, 22]. In order to reduce carbon footprint derived, efforts should be made to promote in the process of contracting electricity supply that most of them come from renewable sources, such as photovoltaic or wind [23], including environmental clauses in the contracting process [24]. (3) Where: SWAP is expressed in EUR, eSWAP is energy expressed in MW, DPM is expressed in EUR/MWh, and cSWAP is expressed in EUR/MWh. 4. C ONCLUSIONS On the other hand, PPA coverage is specific to long-term contracts (> 5 years). This option has an eminent financial nature and is being used as a guarantee for financing energy generating plants from renewable sources. The possibilities of managing the purchase of energy have been presented to large consumers, such as hospitals. To have personnel qualified to assume the responsibility of studying the different modalities of purchase that the traditional fixed contract or indexed with a marketing company will bring an enormous benefit to the hospital management. It provides long-term certainty for both the generator and the consumer. Through this contract, a seller can secure the income of a certain economic amount to, generally, finance its generating plant and a buyer assures the cost of supply during the time of the contract. As in the case of SWAP, defining an expected generation-consumption scenario will be the most beneficial for the hospital manager. This central scenario is defined with a tolerance range. A cost calculation criterion is established for consumption scenarios that are not contemplated. The very specific tools, such as coverages, which are very unknown to hospital managers, are really interesting in order to reduce risk by guaranteeing a steady cost of energy. The possibility of becoming a direct consumer is an advantageous option in terms of the reduction of tax burdens that involves. 5. A CKNOWLEDGEMENTS Becoming a direct consumer offers the possibility of going directly to the daily market to purchase energy according to your consumption forecast. In this way, the consumer pays the energy at the agreed price plus the costs of the system. It is an opportunity to reduce costs if healthcare engineers dispose an adequate consumption forecast, thus avoiding penalties for detours. Not having to participate in other costs of the system (such as efficiency, social bonus, etc.) is the great advantage of this modality. This can translate into a saving of 1 EUR/ MWh compared to contracts made through a sales company. In contrast, there are disadvantages, for example: a direct consumer must present guarantees to the electricity system operator, and their annual consumption must be more than 4 GWh. Within this option, serious modalities are presented, such us not having a representative, have a representative in its own name or in someone else's name. The authors would like to acknowledge the European Social Fund and the University of Extremadura for supporting this research work. This study has been carried out through the GR -18029 research project linked to the VI Regional Plan for Research, Technological Development and Innovation of the Autonomous Community of Extremadura 2017-2020. 6. R EFERENCES [1] J. W. Bujak, «Production of waste energy and heat in hospital facilities,» Energy, vol. 91, pp. 350-362, 2015. [2] Singer, Brett C. «Hospital Energy Benchmarking Guidance-Version 1.0», Berkeley, CA, 2009. [3] Instituto para la Diversificación y el Ahorro Energético, Informe anual de consumos energéticos (2015). 15