Energy and environmental sustainability of a zero energy & zero carbon building

Resumen

The building sector is largely responsible for energy consumption and carbon emissions. As a result, the European Union has developed several directives, including an updated Energy Efficiency of Buildings Directive 2018/844/EU, designed to reduce the energy demand of buildings and improve the energy efficiency of their facilities by integrating renewable energy. This PhD thesis shows a methodology development for ZEB buildings, framed within the European regulations. The target building is an existing Zero Energy Building and Zero Carbon Emissions building called LUCIA, located on the university campus in Valladolid, Spain. The building LUCIA has the highest innovative technologies in energy systems, design and construction elements. It is currently considered one of the top three buildings with the highest LEED certification in the world. According to current European regulations, buildings will become self-sufficient in terms of energy after 2020. This PhD thesis will help to understand the changes in energy consumption within a long-term timeframe, for such zero-energy buildings. LUCIA ZEB is designed to supply electricity, cooling and heating needs through solar energy, Photovoltaic Systems (PV), biomass and an Earth-Air Heat eXchanger (EAHX), besides a Combined Heat Power (CHP). An analysis of energy efficiency, carbon emissions, and operating costs of renewable energy technologies implemented in a multipurpose zero-energy building is presented in this PhD. The monitoring data, obtained by dynamic monitoring through SCADA was implemented in the control room of the building, and provides the necessary information on the needs of electricity, cooling and heating. All the renewable energy systems studied showed positive benefits in terms of economic savings and reductions in carbon emissions, although these benefits are dependent on the particular features of the building, the Smart Control, SCADA, and the climate. Therefore, the design of these strategies for the new ZEB must keep these factors in mind. The combined use of photovoltaics, biomass, and EAHX reduces carbon emissions in the ZEB LUCIA building from 123 to 170 tons/year compared to other non-renewable fuels. This results in economic savings in the operation of energy systems from 43 to 50 thousand €/year. The classification of buildings within the ZEB target, by means of indicators, is a strong and useful tool. These indicators are very useful for the energy analysis of the nZEB according to the requirements of the European standard and for comparison with other nZEB. Once all of the energy parameters of the building have been obtained by dynamic monitoring, the construction model is simulated with DesignBuilderV5 and its EnergyPlus building energy engine. Based on this data, an energy balance of ZEB is carried out, which will contribute to planning preventive actions against real energy consumption. Thus, improving the management and control of both the building and its systems. The classification of the building by indicators demonstrates how the LUCIA building is included within the requirements established by the EPBD. The primary energy indicator obtained is 67 kWh/m2-year, and 121 kWh/m2-year for renewable energy generation, with respect to 55 kWh/m2-year and 45 kWh/m2-year set as reference in Europe. The Renewable Energy Ratio (RER) is 0.66. Over the last few years, studies have predicted an increase in the overall air temperature due to climate change. Today’s society is already sensing this change, which could have a negative impact on the environment. Efforts are being made to seek all possible measures to curve it. One of the consequences of this temperature rise is the indoor comfort within buildings. This may cause higher energy consumption and operational costs, while reducing the useful lifetime of air-conditioning equipment. The possible effects of climate change on its zero energy status, is studied in this PhD thesis. The calibrated building model is simulated and the energy consumption for 2020, 2050 and 2080 is analysed within the climatic conditions of Valladolid, a continental climate. The development of expected changes in climatic conditions due to climate change, have been obtained through the methodology developed by the University of Southampton called CCworldweathergen. This PhD thesis shows quantitatively how the demand for cooling would increase about 25% by 2050 and 2080, while heating would decrease. This will increase the overall demand for burning more biomass to cover the added demand in absorption cooling systems. Furthermore, the previous excess generated electricity of the building by photovoltaics would then be totally consumed within the building due to the increased demand. This implies that the installed systems will operate for longer hours, increasing maintenance and replacement costs. Therefore it is possible to quantify expected changes in energy consumption and anticipate this change by preparing preventive interventions, ultimately improving the management and control of both the energy systems and the building. It will also be possible to verify that the building under study will continue to meet ZEB requirements in the future, as is the case in the LUCIA building.