Economics and climate change emissions analysis of a bioclimatic institutional building with trigeneration and solar support

A new research university building with a useful area of about 3000 m2 has recently been constructed in Lleida (Spain) as an example of a sustainable energy efficient institutional building. The building is provided with passive measures in the envelope as well as a wide variety of active measures in the installed energy systems. Non-conventional energy systems such as solar photovoltaic arrays, thermal collectors, an internal combustion engine cogeneration, and an absorption chiller are in place. The standard systems, namely two 320 kW condensation boilers and a 419 kW compression chiller, are also included in the building for back-up and for comparison purposes. To assess the potential energy, economic and CO2 savings of the building a simplified model is developed and the main results discussed. For nominal electricity and gas average prices about 11.5 k€ of savings are achieved. This represents energy cost reductions of 35–58%, a payback period of 20 years and about 56 tons per year of saved CO2 emissions. The presence of the absorption chiller is found essential to maximize buildings economic and CO2 emissions savings. This work also includes parametric studies for natural gas and electricity prices as well as results for other possible combinations with only one or several of the installed systems in operation.