Evolution of magnetic fields and energetics of flares in active region 8210

To better understand eruptive events in the solar corona, we combine sequences of multi-wavelength observations and modelling of the coronal magnetic field of NOAA AR 8210, a highly flare-productive active region. From the photosphere to the corona, the observations give us information about the motion of magnetic elements (photospheric magnetograms), the location of flares (e.g., H$\alpha$, EUV or soft X-ray brightenings), and the type of events (H$\alpha$ blueshift events). Assuming that the evolution of the coronal magnetic field above an active region can be described by successive equilibria, we follow in time the magnetic changes of the 3D nonlinear force-free (nlff) fields reconstructed from a time series of photospheric vector magnetograms. We apply this method to AR 8210 observed on May 1, 1998 between 17:00 UT and 21:40 UT. We identify two types of horizontal photospheric motions that can drive an eruption: a clockwise rotation of the sunspot, and a fast motion of an emerging polarity. The reconstructed nlff coronal fields give us a scenario of the confined flares observed in AR 8210: the slow sunspot rotation enables the occurence of flare by a reconnection process close to a separatrix surface whereas the fast motion is associated with small-scale reconnections but no detectable flaring activity. We also study the injection rates of magnetic energy, Poynting flux and relative magnetic helicity through the photosphere and into the corona. The injection of magnetic energy by transverse photospheric motions is found to be correlated with the storage of energy in the corona and then the release by flaring activity. The magnetic helicity derived from the magnetic field and the vector potential of the nlff configuration is computed in the coronal volume. The magnetic helicity evolution shows that AR 8210 is dominated by the mutual helicity between the closed and potential fields and not by the self helicity of the closed field which characterizes the twist of confined flux bundles. We conclude that for AR 8210 the complex topology is a more important factor than the twist in the eruption process

NZEB, cost- and comfort-optimal retrofit solutions for an Italian Reference Hotel

Building upon the implementation of EBPD recast in the large majority of EU Member States, this paper studied how far cost-optimality is from the Nearly Zero Energy Building (NZEB) performance level for an Italian Reference Hotel (RH) undergoing major renovations. The energy performances of retrofit options for the RH were compared with the Italian NZEB requirements. Simulations results confirmed that the Italian NZEB target is reachable. However, the financial analysis of these retrofit options denounced a worrying gap between financially interesting solutions and NZEB ones. Then, through a novel comfort-optimal approach, the comfort-related consequences of the proposed retrofit options were investigated

modeling building energy demand profiles and district heating networks for low carbon urban areas

Abstract Urban energy consumptions growth has become an urgent topic that requires solutions for significantly reduce carbon emission in the next decades. This paper aims in exploring the integration of building performance improvement and low carbon district heat technological choices by considering the upgrade of conversion technologies, efficiency and the exploitation of local resources. The paper is based on a GIS-based model that spatially characterize the space heating demand of urban buildings. Starting from clustering buildings with similar thermo-physical characteristics, the total energy use of buildings can be depicted and compared with the energy balance data of the city in order to scale the bottom-up results for matching the total load. Reasonable energy efficiency measures are further proposed by considering three different scenarios up to 2050. Long-term building scenarios are applied to a district heating simulation model for investigating how the reduction of building heat demand will impact the district heating production and operations. In particular, the combination of the building model and the district heating model aims at exploring the effects of district network expansion or new low carbon investments from an economic and environmental perspective. The model has been successfully applied to the city of Turin, Italy and the city of Stockholm, Sweden. The flexibility of the approach may allow it to be easily adjusted to different urban areas for providing indications on cost-effective strategies for efficient, low-carbon heat solutions in integrated energy systems. Results highlight that finding synergies between the demand and supply sector will lead to environmental and economic benefits, in particular for district-heated cities

Identification of the Retrofit Actions to Achieve Cost-Optimal and NZEB Levels for Residential Buildings in Istanbul Considering the Remaining Building Lifetime

Cost-optimal and nearly-zero energy building (NZEB) levels are two interrelated concepts identified for upgrading energy performance of buildings in Europe. In parallel, many research activities on retrofitting existing buildings in Turkey follow the methodology framework introduced by the European Commission. However, in Turkey, there is a process called “urban transformation” due to the earthquake risk, but the practice is based on new construction after demolishment of existing buildings. Especially in Istanbul, this process has been conducted rapidly. This specific aspect requires assessment of cost-optimal retrofit analyses considering the remaining lifespan of analysed buildings. This study presents a cost-optimality assessment method for retrofitting towards NZEB in Turkey. The method integrates payback period and investment cost assessment to the methodology in order to obtain whole picture for retrofit alternatives. In the paper, suggested method is applied to a reference residential building in Istanbul. After the initial cost-optimal analyses, payback periods and initial investment costs for selected retrofit packages are assessed considering the future lifespan of the building. Together with these, possible subsidy opportunities are also investigated. Results show that, if the expected future lifespan is higher than 10 years, retrofit actions achieving 56.2kWh/m2y primary energy consumption level are considerable. Subsidies are beneficial to obtain reasonable initial investment costs

Effect of Economic Indicators on Cost-Optimal Energy Performance Levels of Residential Buildings Retrofits in the Mediterranean Region of Turkey

This study aims to analyse the effect of economic indicators on cost-optimal levels of residential building retrofits in Mediterranean region of Turkey. Sensitivity analyses were applied on the cost-optimality calculation results for the residential reference building. The sensitivity analyses address discount rate and potential investment cost decreases. Results reveal that 6% variation in the discount rate corresponds to more than 30 kWh/m2y difference in the primary energy consumption of the cost-optimal solutions. Potential investment cost decreases for certain retrofit measures are also effective on identified cost-optimal levels and subsidy opportunities appear as an effective tool to achieve higher energy efficiency in existing buildings and to stimulate building energy retrofits

Identification of the Retrofit Actions to Achieve Cost-Optimal and NZEB Levels for Residential Buildings in Istanbul Considering the Remaining Building Lifetime

Cost-optimal and nearly-zero energy building (NZEB) levels are two interrelated concepts identified for upgrading energy performance of buildings in Europe. In parallel, many research activities on retrofitting existing buildings in Turkey follow the methodology framework introduced by the European Commission. However, in Turkey, there is a process called "urban transformation" due to the earthquake risk, but the practice is based on new construction after demolishment of existing buildings. Especially in Istanbul, this process has been conducted rapidly. This specific aspect requires assessment of cost-optimal retrofit analyses considering the remaining lifespan of analysed buildings. This study presents a cost-optimality assessment method for retrofitting towards NZEB in Turkey. The method integrates payback period and investment cost assessment to the methodology in order to obtain whole picture for retrofit alternatives. In the paper, suggested method is applied to a reference residential building in Istanbul. After the initial cost-optimal analyses, payback periods and initial investment costs for selected retrofit packages are assessed considering the future lifespan of the building. Together with these, possible subsidy opportunities are also investigated. Results show that, if the expected future lifespan is higher than 10 years, retrofit actions achieving 56.2kWh/m2y primary energy consumption level are considerable. Subsidies are beneficial to obtain reasonable initial investment costs

Occupant behaviour lifestyles and effects on building energy use: Investigation on high and low performing building features

Occupant behaviour is known to be one of the key sources of uncertainty in the prediction of building energy use. Extended literature reviews linked the large performance gaps between residential buildings with same properties and similar climate conditions to the way occupants interact with the building envelope and systems. Furthermore, in the last decades, more stringent energy codes have led to energy efficient design strategies with the aim of reaching the nearly-zero energy target. The success of these strategies is now heavily dependent on how the occupants interact with the building, or rather, on the energy-related lifestyles they assume. In line with this, the present study employs building simulations to demonstrate the potential impact of different occupant behaviour lifestyles on the energy use of a Mediterranean (i) residential nearly-zero energy building (nZEB) under-construction and a (ii) Reference Building (RB) whose envelope-driven loads dominate the consumption profile

insights into the effects of occupant behaviour lifestyles and building automation on building energy use

Abstract In order to optimize building energy consumption, Member States will have to establish minimum efficiency requirements for systems, and promote the introduction of active control system in new constructions or major renovations. Energy saving, plant efficiency and environmental sustainability are also factors delineating smart buildings. Interestingly, occupant behaviour is known to be one of the key sources of uncertainty in the prediction of building energy use. The success of automation strategies is recognized to be dependent on how the occupants interact with the building. The present research describes the effect of different building occupants' lifestyles and building automation on a high performing building

Performance Assessment of a Solar Assisted Ground Source Heat Pump in a Mountain Site

Abstract Systems based on the integrated use of multiple renewable energy sources, such as “Solar Assisted Geothermal Heat Pumps” (SAGHPs), seem to increase efficiency and overcome limits of the use of traditional heat pump systems. In this work, a \SAGHP\ providing energy for heating and \DHW\ of a newly built restaurant in an Alpine ski park was analyzed through transient simulations with TRNSYS®, following the collection of information about the system component, the operation and the weather conditions of the mountain site. The annual energy balance allowed different system operation modes to be compared

Review of health and well-being aspects in Green Certification Protocols

Over the past decades, the world-leading Green Certification Protocols have paid increasing attention to health-related aspects of buildings. However, the way and the extent to which green certifications currently account for these aspects vary largely. This paper aims to review and compare four certification protocols, namely LEED v4, BREEAM 2018, WELL v2, and MINERGIE-ECO v1.4, and to provide insights on how aspects related to occupants’ health and well-being and their influencing factors are accounted for and assessed. To that scope, indicators used to assess the users' health and well-being are extracted from each certification and compared. Indicators traditionally used to evaluate IEQ in buildings (thermal, indoor air quality, visual and acoustic) based on international or national standards were found in all certifications. However, the analysis highlights that their assessment and verification stage (e.g., pre- vs. post- occupancy) significantly differs from one label to another. More “advanced” indicators, which are related to mind, promotion of physical activities, and community engagement, have come to light. While a comprehensive approach to the evaluation of well-being might include a combination of objective (e.g., measurement-based evaluations) and subjective components (e.g., people’s subjective evaluation), the review highlighted that only in one protocol (i.e., WELL), direct feedback from occupants is kept in the loop for further optimization of the building management during operation. Otherwise, indicators are mainly verified through quantitative measurements, reports, or implemented policies