Embodied greenhouse gas emissions from PV systems in Norwegian residential Zero Emission Pilot Buildings

Abstract

Printed by NTNU Grafisk senter i This thesis concerns the use of solar energy in energy efficient buildings. More precisely, the topic is photovoltaic-thermal (PV/T) solar energy systems, and how these can be used to provide renewable energy in zero emission buildings. PV/T modules are a hybrid between photovoltaic (PV) modules and solar thermal collectors, and therefore generate electricity and thermal energy simultaneously. The objective of the thesis was to investigate the potential of PV/T systems to minimize the life cycle greenhouse gas emissions of a residential building.The building sector accounts for around one third of the global energy use and about half of the electricity use, and is therefore a key area to focus on in the effort to mitigate climate change and to create more sustainable societies in the future. The environmental impact of buildings need to be lowered by reducing the energy demand during construction and operation, but also by replacing polluting energy sources with renewable ones. The European Union has demanded of its member states that all new buildings shall be nearly zero energy buildings by 2020.Solar energy is well-suited to use in buildings, and can supply electricity, lighting, heating, and cooling. Once installed, a solar energy system supplies energy without pollution, is silent, have few or no moving parts, and can also be integrated into the building itself. In order to do investigate how PV/T systems can best be used in buildings to minimize life cycle emissions, the systems have been studied both in terms of energy performance and in terms of greenhouse gas emissions.The main research method in this thesis has been simulation of solar energy systems in buildings. Using simulations, PV/T systems have been compared to other solar energy systems with separate PV modules and solar thermal collectors. The simulation studies were performed in the simulation programs Polysun and PVsyst, and were based on commercial solar energy products available on the current market. The use of heat pumps, air-source and ground-source, in combination with solar energy systems was also studied.Two case buildings, the ZEB residential concept and the Living Lab, have been used in the simulation studies. The buildings are two of the pilot buildings of the Norwegian Research Centre for Zero Emission Buildings (the ZEB Centre). Both buildings are single family residential buildings located in Central or Southern Norway, and are designed to meet the Norwegian passive house requirements.The embodied emissions of the solar energy systems were determined using elements of life cycle assessments (LCA). A review of previous research found few studies of the environmental impact of PV/T modules, especially using industrially produced modules. The embodied emissions of such a PV/T module was therefore determined in this thesis, based on a combination of data from databases and information from module producers. The embodied emissions of the case buildings and the other solar energy systems studied were d...

Microgeneration of Electricity Using a Solar Photovoltaic System in Ireland

“…GHG payback time (GPBT) is defined as the number of years it takes solar PV system to pay back its embodied emissions through solar PV generation. The GPBT [41] is described by Equation 11:…”

“…To assess the GBPT of the project, the emissions associated with the embodied energy of the proposed solar PV system were determined [41]. Calculated solar PV system emissions ranged between 50 g to 120 g CO 2 eq.…”

“…Total carbon credits earned = Net CO 2 mitigation•price (16) where, price = Current market trading price (€21 per tonne CO 2 eq.) [41] = (1315 t of CO 2 eq. )•(€21per t CO 2 eq.)…”

Optimal Decision-Making of Renewable Energy Systems in Buildings in the Early Design Stage

“…High-performance buildings have been regarded as one of the most advanced and effective ways of reducing greenhouse gas emissions [6][7][8]. The successful implementation of high-performance building requires the application of renewable energy systems (RES), as well as passive building design approaches [9,10].…”

From Zero Emission Buildings (ZEB) to Zero Emission Neighbourhoods (ZEN): A Mapping Review of Algorithm-Based LCA

“…This demonstrates how the carbon footprint "offers the potential to get life cycle approaches into organisations and decision making contexts which pure LCA did not reach yet" [19]. The starting point is the real-life experiences with the zero emissions buildings tool (ZEB tool), developed in the FME ZEB project [4] to calculate the carbon footprint of zero emission buildings (ZEB) and tested on several pilot buildings [13]. It is based on type III environmental product declarations (EPD) developed in accordance with the standards ISO 14025 [14], ISO 21930 [15], and EN 15804 [16].…”