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In recent years, energy efficiency and the decarbonization of the building sector have become key goals in Europe. However, substantial efforts are still needed to support the increase in on-site energy generation from renewable energy sources (RES) and to phase-out the use of fossil fuels. Moreover, this challenge must be backed by financial mechanisms provided by Member States. In this context, the aim of this work is to investigate different RES generation layouts for a reference office building in Italy and to determine whether it can achieve the goal of a net zero energy building (net ZEB) or a positive energy building (PEB). Different layouts are analyzed from both energy and economic perspectives through dynamic energy simulation, considering different financial schemes, such as "net metering" (SSP) and "premium tariff" (RID). The results show that the energy performance improves due to the size and the characteristics of the PV system. However, the avoided operating costs due to RID increase linearly, while the economic benefits provided by the SSP scheme encourage an appropriate design of the renewable energy system, avoiding oversizing for economic profitability. [ABSTRACT FROM AUTHOR]

Zero-emission buildings, which do not emit CO2 or other greenhouse gases throughout their entire life cycle, play a crucial role in sustainable development and the fight against climate change. Achieving carbon neutrality in construction requires considering emissions associated with material production, construction, operation, as well as demolition and disposal. These buildings utilize energy-efficient technologies, renewable energy sources, and low-carbon materials, minimizing their environmental impact. The building sector accounts for a significant percentage of global greenhouse gas emissions, making it a key area for climate action. In Poland, where aging and energy-inefficient buildings prevail, the need for a transition towards zero-emission buildings is particularly urgent. This paper assesses the feasibility and hurdles of retrofitting existing buildings to achieve zero emissions by utilizing renewable energy systems like solar photovoltaic and heat pump technologies. The publication discusses the technical, economic, and legal aspects of this transformation, with particular emphasis on the Polish context and available support programs. The purpose of this publication is to disseminate practical knowledge and foster innovation among architects, investors, and decision-makers engaged in the development of a sustainable built environment. A key example is Net Zero Energy Buildings (NZEBs), which generate as much energy as they consume over a year through technologies such as photovoltaic panels, solar collectors, and heat pumps. NZEBs combine effective insulation, energy-efficient systems, and smart energy management to minimize consumption, and may even produce excess energy that feeds back into the grid. Despite challenges in construction and maintenance, the increasing adoption of zero-emission and NZEBs worldwide reflects their long-term ecological, economic, and health benefits. The focus of this publication is to analyze the potential for transforming standard buildings, as defined by current regulations, into zero-emission buildings powered entirely by renewable energy sources. This case study analyzes the energy potential of a residential building located in Krakow, Poland. The building's energy efficiency potential was assessed through computer simulations using Audytor OZC software (version 7.0 Pro, Sankom), taking into account local climate conditions and building standards. The study analyzed the impact of various strategies, such as upgrading thermal insulation, using energy-efficient windows, and installing photovoltaic panels, on energy consumption and CO2 emissions. [ABSTRACT FROM AUTHOR]

Nearly-Zero-Energy and Zero-Emission Buildings are one fundamental part of the world strategies addressed at mitigating the global warming trend and coping with the goal of setting 1.5 °C the planet temperature increase with respect to the pre-industrial conditions. The present paper refers to a specific case study, the Smart Energy Building (SEB) located in the Savona Campus of the University of Genoa. The SEB is a very innovative building for both the envelope (ventilated highly insulated facades) and the energy systems (including a ground coupled heat pump and an exhaust air-to-air heat pump for building ventilation); the building is equipped also with a PV module field on the rooftop for electricity production. The present paper first evaluates the heating and cooling loads of the building by means of an EnergyPlus model and analyses the impact of different control strategies related to the temperature setpoints. In particular, case #1 refers to a minimum temperature to be assured by heating only in winter and to a maximum one to be avoided by cooling only during summer; on the other hand, in case #2 the temperature inside the building is controlled within a defined range (both heating and cooling modes) all year long. From EnergyPlus simulations, the hourly heat loads have been averaged as monthly values and employed for the calculation of the required overall length of the ground heat exchangers of the geothermal heat pump of the SEB building. The ground-side analysis is performed by applying the Authors' ASHRAE- T p8 method, in its recently released web version. For the BHE (borehole heat exchanger) calculations, a parametric analysis has been performed in terms of ground thermal conductivities. Finally, the PV electrical production has been estimated by EnergyPlus simulations and compared with the corresponding measured one, thus showing the net energy zero behaviour of the present building. [ABSTRACT FROM AUTHOR]

Energy sharing between multiple zero-emission buildings is an important energy management strategy that can reduce the negative effects of energy mismatch. This study proposed a cross-harbour nearshore and offshore ocean renewable energy system connected by submarine cables to support two large-scale zero-emission harbour-to-harbour buildings in the Greater Bay Area. Two scenarios named were proposed based on the absence or presence of intermediate submarine cables and the energy sharing between the two regions. Eight representative renewable energy combinations consisting of wind turbines, tidal stream generators, and floating photovoltaic systems were designed to demonstrate the impact of different renewable energy systems on the overall performance. Two integration policies were designed based on the different renewable energy policies of the two regions, and their characteristics were tested. The impact of the submarine cable capacity on the system performance, the possible installation of batteries at offshore sites to replace some of the submarine cable capacity, and the impact of realistic land prices in Hong Kong and Macau on different renewable energy combinations were also investigated. The results showed that the combination with only the nearshore wind turbine system achieved the best economic performance, with relative net present values of 25.63 × 108 and 30.78 × 108 HKD in the two scenarios when the nearshore and offshore sites had equally cheap land prices. When the true land price was introduced, only the combinations with the all-offshore system had positive relative net present values, while the combinations with nearshore systems all had negative relative net present values. Meanwhile, batteries could not replace the role of submarine cables in this system. Installing intermediate submarine cables and sharing energy between the two regions could significantly improve the energy matching by 8 to 21% and economic performance by 4.44 × 108 to 5.30 × 108 HKD of the system. When all submarine cables were maintained at 40% of their maximum capacity, the energy usage ratio could be guaranteed to be 100% without dumped energy. • Nearshore and offshore ocean-energy-supported zero-emission public buildings. • Co-ordinations of energy sharing between cross-harbour zero emission system. • Energy exchange and sharing supported by submarine cables. • Integrated feed-in tariff policy in HK and MO to support energy exchange. • Impact of the realistic land prices on the performance of zero-emission system. [ABSTRACT FROM AUTHOR]

Responsive building envelopes (RBEs) are central to developing sustainability strategies for zero emission/energy buildings (ZEBs). RBEs are a large group of complex technologies and systems, which is why multi-criteria decision making (MCDM) methods are helpful to navigate sustainability assessments considering various performance indicators. This article first provides a literature review of assessment criteria and key performance indicators for RBEs and an analysis of existing robustness-based MCDM methods. Then, a methodological approach to assess RBE designs in ZEB projects is proposed as an extension of a novel robustness-based MCDM method that normalizes the objective functions according to defined targets and combines them into one comprehensive indicator (MT-KPI), thereby eliminating the need to weight objectives. The proposed methodological approach is finally tested on a case study of a Norwegian ZEB, where five competitive RBE designs (including building integrated photovoltaics, phase change material, and electrochromic windows) and eight occupancy and climate scenarios are investigated considering three main performance areas: energy use, thermal comfort, and load matching. The results in the case study show that with the proposed MCDM approach the different designs have MT-KPI values between 1.4 and 12.8, where a lower value is better. In this specific case, the most robust building RBE alternative was identified as the one with electrochromic windows and a control based on incident solar radiation and indoor air temperature.

Abstract This paper explores the most influential aspects regarding the environmental and economic performance of zero-energy and zero-emission buildings and proposes a pathway for transition in building solutions. A representative zero-energy office building in Norway is investigated with alternative design solutions to achieve zero-emission status i.e., the extensive use of locally generated energy through photovoltaic (PV) panels and the use of materials with low embodied emissions, such as low-carbon concrete and wood. A life cycle environmental and economic assessment is performed to evaluate specific indicators during the building life cycle: cumulative energy (CED), global warming potential (GWP), and equivalent annual cost (EAC). The extensive use of PV panels was most effective in lowering the operational energy because it reduced the CED by about 30% compared to the building as-built. However, the extensive use of wood in the construction contributed the most to GWP reduction, with around 30% decrease compared to the building as-built. Finally, the differences in EAC were interestingly insignificant among the alternatives, with the investment costs dominating the EAC for all designs examined. The findings of this paper emphasise that a full compensation of the life cycle GHG emissions from materials is difficult to achieve through renewable energy, even with extensive use of PV panels, especially in a low-carbon grid situation as in Norway. A pathway strategy from zero-energy towards zero-emission buildings must therefore strongly focus on the materials' embodied energy and emissions because low operational energy demand is already a regulatory priority in most countries. [ABSTRACT FROM AUTHOR]

Different designs and concepts of low-energy and zero-emission buildings (ZEBs) are being introduced into the Norwegian market. This study analyses and compares the life cycle emissions of CO2 equivalents (CO2e) from eight different single-family houses in the Oslo climate. Included are four ZEBs: one active house, two passive houses, and a reference house (Norwegian building code of 2010). Monthly differences in CO2e emissions are calculated for the seasonally sensitive Norwegian context for electricity generation and consumption. This is used to supplant the previous applied symmetric weighting approach for CO2e/kWh factors for import and export of electricity for the ZEB cases. All the ZEBs have lower use-stage emissions compared with the other buildings or the reference case. Embodied impacts are found to be 60-75% for the analysed ZEB cases, confirming the importance of embodied impacts in Norwegian ZEBs. The lowest total emissions were from the smallest ZEB, emphasizing area efficiency. The highest emissions were from the reference case. By abandoning the symmetric approach, a new perspective was developed for assessing the performance of ZEBs within the Norwegian context. One of four ZEB cases managed to balance out its annual energy-related emissions. [ABSTRACT FROM AUTHOR]

Today's buildings are becoming more insulated and airtight to reduce transmission heat losses. Energy use for ventilation can represent up to half of these buildings' total energy use. Heat recovery in ventilation and demand-controlled ventilation (DCV) are energy-efficient measures to reduce ventilation energy use, especially when combined. However, this study revealed that the often-overlooked longitudinal heat conduction (LHC) in aluminium rotary heat exchangers might yield less efficient heat exchangers, particularly for intended high-efficiency heat recovery at low ventilation rates in DCV. This study presents a theoretical method to assess the effect of LHC on the amount of energy used to heat ventilation air for several ventilation strategies. The method is demonstrated in a case study for a virtual office building in a cold climate (Oslo, Norway). When neglecting the LHC effect, the energy used to heat the supplied air using DCV with a rotary heat exchanger is about three times smaller than when considering LHC. Unlike earlier studies, we find that DCV may consume more ventilation heating energy than constant air volume (CAV) ventilation when the selected wheel is deep and oversized due to LHC. This study highlights the need to design rotary heat exchangers carefully in order to account for the LHC effect, particularly when targeting zero emission buildings (ZEB). • Understanding the role of longitudinal heat conduction of heat wheel in ventilation. • A deep and oversized rotary heat exchanger yields degraded energy performance. • New insights into energy inefficient combination of heat recovery and DCV. • Contribute to closing the energy performance gap and facilitating zero emission. [ABSTRACT FROM AUTHOR]

Responsive building envelopes (RBEs) are central to developing sustainability strategies for zero emission/energy buildings (ZEBs). RBEs are a large group of complex technologies and systems, which is why multi-criteria decision making (MCDM) methods are helpful to navigate sustainability assessments considering various performance indicators. This article first provides a literature review of assessment criteria and key performance indicators for RBEs and an analysis of existing robustness-based MCDM methods. Then, a methodological approach to assess RBE designs in ZEB projects is proposed as an extension of a novel robustness-based MCDM method that normalizes the objective functions according to defined targets and combines them into one comprehensive indicator (MT-KPI), thereby eliminating the need to weight objectives. The proposed methodological approach is finally tested on a case study of a Norwegian ZEB, where five competitive RBE designs (including building integrated photovoltaics, phase change material, and electrochromic windows) and eight occupancy and climate scenarios are investigated considering three main performance areas: energy use, thermal comfort, and load matching. The results in the case study show that with the proposed MCDM approach the different designs have MT-KPI values between 1.4 and 12.8, where a lower value is better. In this specific case, the most robust building RBE alternative was identified as the one with electrochromic windows and a control based on incident solar radiation and indoor air temperature. [ABSTRACT FROM AUTHOR]