ENERGY EFFICIENCY OF EXISTING BUILDINGS: OPTIMIZATION OF BUILDING COOLING, HEATING AND POWER (BCHP) SYSTEMS Giorgio Pagliarini, Sara Rainieri and Pamela Vocale * Department of Industrial Engineering, University of Parma, Parco Area delle Scienze 181/A - 43124 Parma – Italy ABSTRACT The enhancement of the energy efficiency of existing buildings represents an important task, specifically addressed by the European Directives. Among the currently available technologies to achieve this issue, the combined generation of heat and power (CHP) is found. Its higher efficiency with respect to the separate production of heat and power mainly depends on the occurrence of a profitable use of the cogenerated heat. This technology is now rapidly spreading because of its benefit from both the energy and the environmental sustainability points of view. However, in order to properly size the CHP system capacity and operation strategy, some specific design rules have to be identified. In particular, the CHP systems optimal design requires the building energy loads to be known on a hourly time scale. In the present paper a simplified procedure for estimating the hourly energy load for space heating and cooling of existing buildings is applied to the assessment of building cooling, heating and power systems energy performance. The results, obtained for a complex nine storey building located in six representative climates, point out that the suggested method allows to estimate the primary energy savings index with an approximation error, averaged over the considered combined generation system capacity range, less than 2.8% and 3.3% in continuous and time scheduled plant operation, respectively. 1. INTRODUCTION In the last decade the energy efficiency of the new buildings has been significantly improved, according to the European directives requirements. However the existing buildings stock is a wide sector in which there is a huge potential for energy saving [1]. Moreover the European Union has established specific requirements for improving the energy efficiency of existing buildings, thus pushing many governments to define suitable financial instruments to support this strategy. 1423 * Corresponding Author: Tel.: +39 0521 905855; fax: +39 0521 905705 E-mail address: pamela.vocale@unipr.it (P. Vocale)