The renewable energy solutions are being actively applied to achieve nearly and net zero energy buildings, however very few studies have reported the environmental impact of applied renewable energy ...sources (RES) on a net zero energy building from the perspective of both embodied and operational greenhouse gas emissions (GHG). As the energy performance of buildings improves, the significance of embodied energy and embodied greenhouse gases increases when compared to the operational impacts. These trends can become more important when the technology for net zero energy and off-grid buildings is being advanced especially when necessitating use of energy storage (batteries).
The aim of this study is to advance new knowledge on the impact of local renewable energy solutions on the GHGs of nearly zero energy buildings by considering both operational and embodied impacts. This study presents the case study of a net zero residential building and evaluates three main cases of annual net zero electricity (Case 1), off-grid electricity (Case 2) and 100% solar thermal heat (Case 3) and in total presenting six variations of building integrated RES technologies. The results indicate that the embodied GHG impacts are responsible for two thirds of GHG impacts which is opposite when compared to an nearly zero energy building that is connected to the grid and district heat network (BAU case). When RES technologies are integrated with the building and electricity is produced from renewable sources the ‘Annually net zero electricity’ case produces almost 40% less GHG emissions when compared to the ‘BAU’ case. For the ‘off grid electricity’ case using Li-ion batteries for seasonal energy storage, resulted in the highest embodied GHG emissions due to immature technology.
•New knowledge on the impact of renewable energy solutions on the GHGs of NZEBs.•Calculated the embodied and operational impacts of nZEB.•Case study of a nearly zero energy building.•Presents six varying renewable energy technologies applied to a nZEB building.•Off-grid NZEB building case resulted in the highest embodied and operational GHGs.
Urban air undergoes transformations as it is actively circulated throughout buildings via ventilation systems. However, the influence of air exchange between outdoor and indoor atmospheres on urban ...air pollution is not well understood. Here, we quantify how buildings behave as a dynamic source and sink for urban air pollutants via high-resolution online mass spectrometry measurements. During our field campaign in a high-performance office building, we observed that the building continually released volatile organic compounds (VOCs) into the urban air and removed outdoor ozone and fine particulate matter. VOC emissions from people, their activities, and surface reservoirs result in significant VOC discharge from the building to the outdoors. Per unit area, building emissions of VOCs are comparable to traffic, industrial, and biogenic emissions. The building source-sink behavior changed dynamically with occupancy and ventilation conditions. Our results demonstrate that buildings can directly influence urban air quality due to substantial outdoor-indoor air exchange.
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•Modern buildings continually release volatile chemicals into the outdoor atmosphere•Buildings can be significant emission sources of reactive monoterpenes and siloxanes•Building source-sink behavior changes with human occupancy and ventilation conditions•Direct VOC emissions from buildings must be considered in urban air pollution models
Buildings account for a significant fraction of the land area in cities and actively exchange air with their proximate outdoor environments via mechanical ventilation systems. However, the direct impact of buildings on urban air pollution remains poorly characterized. Due to reductions in traffic-associated emissions of volatile organic compounds (VOCs), volatile chemical products, which are widely used inside buildings, have become a major VOC source in urban areas. Indoor-generated VOCs are likely to be an important contributor to the VOC burden of the urban atmosphere, and ventilation systems provide a pathway for VOCs to be released outdoors. Here, we show how modern buildings act as significant emission sources of VOCs for the outdoor environment. Our results demonstrate that future air quality monitoring efforts in cities need to account for direct VOC discharge from buildings in order to capture emerging sources of environmental pollution that can impact the climate and human health.
Wu et al. present real-time direct measurements of urban air pollutant exchange between an advanced ventilation system of a high-performance LEED-certified building and outdoor air. This work demonstrates that modern buildings are a dynamic emission source of climate- and health-relevant volatile chemicals to urban atmospheric environments.
While there are ambitious targets to increase the share of renewable energy technology implementations in the different EU-states, it is increasingly recognized that social acceptance may form a ...factor constraining the expansion of their implementation and use. In order to investigate the Finnish social acceptance towards renewable energy technology implementations, a multiple choice questionnaire was designed with three groups of questions: background information, awareness of renewable energy technologies (RETs), and willingness to invest in RETs. The answers showed that the long-term economic feasibility of using RETs locally in homes was not obvious to 33% of the fifty interviewees. In general, 62% of the interviewees were willing to pay extra cost to obtain green energy. More than half (52.4%) of the interviewees think that public sector should take the first step towards renewable energy production. Likewise, in the respondents’ view, the public sector should take the initiative for implementing RETs by providing business models and incentives to encourage citizens to implement RETs in their houses.
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•Routine use of ethanol-based disinfectants during the COVID-19 pandemic may present a health risk to occupants.•Emissions from ethanol-based disinfectants were characterized in ...real-time via PTR-TOF-MS and HR-ELPI+.•Controlled disinfection experiments were conducted in a tiny house architectural engineering laboratory.•Ethanol-based disinfectants emit a multi-phase mixture of a broad spectrum of VOCs and nano-sized particles.•Inhalation exposure to ethanol and other VOCs is strongly time-dependent during building disinfection events.
The COVID-19 pandemic has resulted in increased usage of ethanol-based disinfectants for surface inactivation of SARS-CoV-2 in buildings. Emissions of volatile organic compounds (VOCs) and particles from ethanol-based disinfectant sprays were characterized in real-time (1 Hz) via a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) and a high-resolution electrical low-pressure impactor (HR-ELPI+), respectively. Ethanol-based disinfectants drove sudden changes in the chemical composition of indoor air. VOC and particle concentrations increased immediately after application of the disinfectants, remained elevated during surface contact time, and gradually decreased after wiping. The disinfectants produced a broad spectrum of VOCs with mixing ratios spanning the sub-ppb to ppm range. Ethanol was the dominant VOC emitted by mass, with concentrations exceeding 103 μg m−3 and emission factors ranging from 101 to 102 mg g−1. Listed and unlisted diols, monoterpenes, and monoterpenoids were also abundant. The pressurized sprays released significant quantities (104–105 cm−3) of nano-sized particles smaller than 100 nm, resulting in large deposited doses in the tracheobronchial and pulmonary regions of the respiratory system. Inhalation exposure to VOCs varied with time during the building disinfection events. Much of the VOC inhalation intake (>60 %) occurred after the disinfectant was sprayed and wiped off the surface. Routine building disinfection with ethanol-based sprays during the COVID-19 pandemic may present a human health risk given the elevated production of volatile chemicals and nano-sized particles.
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•This study presents dynamic simulations of a full scale office building with 160 zones.•Fifteen energy performance cases for three climate zones of Helsinki, London and Bucharest ...were simulated.•Alternative heating and cooling solution using radiant floor panel and radiant ceiling panel were explored.•It is easier to minimize the space heating demand of a building then electricity.•Near optimal solutions for achieving nearly zero energy building based on this study are presented.
Most of the studies encompassing dynamic simulations of multi-storey buildings account only for a few selected zones, to simplify, decrease simulation run-time and to reduce the complexity of the ‘to be simulated’ model. This conventional method neglects the opportunity to see the interaction between different zones as it relates to whole building performance. This paper presents fifteen individual cases of dynamic simulations of a six-storey office building with 160 zones. The energy performance analysis was conducted for three climate zones including Helsinki in Finland, London in the United Kingdom and Bucharest in Romania. For each location, the following three cases were simulated: (i) building as usual simulated according to valid national building codes; (ii) Energy-efficient (EE) case with selected necessary parameters enhanced to reduce total delivered energy demand; and (iii) nZEB case representing partial enhancement of the EE case based on the parametric analysis. The results of nZEB indicate that for Helsinki, it is possible to reduce the space-heating load by 86%, electricity consumed by lighting, appliance, and HVAC by 32%. For London, the heating load is reduced by 95%, cooling load is slightly increased, and electricity demand is decreased by 33%. For Bucharest, 92% of energy in heating can be saved, cooling energy demand was reduced by 60% and electricity consumption by 34%. Based on the nZEB cases for each location, alternative heating and cooling choices of a radiant floor panel system and radiant ceiling panel system were explored. There are small differences in absolute consumption demand for heating, cooling, and electricity for three cases in each location. The specific energy/m2 for heating remained nearly the same in all systems for all three cases in each location. Alternative choices for heating and cooling by using Radiant Ceiling Panel (RCP) and Radiant Floor Panel (RFP) were investigated for all final nZEB cases. Marginal difference in heating energy required for space heating can be seen for London nZEB IHC and London nZEB RCP of 0.8kWh/m2/year and for Bucharest nZEB IHC and Bucharest nZEB RCP case of 1.3 kWh/m2/year. RFP has the availability of large surface area for heat exchange and can provide heating at a low temperature and cooling at high temperature, but requires supporting air based cooling during the humid season. For RCP, the limited temperature exchange surface may increase the airflow rate, but supplies it at a lower temperature for the same load.
Good indoor air quality in office environments is essential for occupant health and productivity. In open-plan offices, displacement ventilation has been recognized for its higher efficiency compared ...to mixing ventilation. This study evaluates the performance of displacement ventilation in an open-plan office under cooling and heating conditions, considering various supply ventilation rates, supply air temperatures, and occupancy levels. Field measurements were conducted over three months in a living laboratory office in a high-performance building. The indoor environment was controlled by an independent variable air volume (VAV) air conditioning system. The supply ventilation rate ranged from 6 to 12 h−1. Real-time measurements of carbon dioxide (CO2) concentrations in the supply air, return air, and breathing zone of the office were conducted to assess occupants’ exposure to CO2 and ventilation efficiency. The results show that the supply ventilation rate plays an important role in shaping the air distribution and overall effectiveness of the mechanical ventilation system. Higher supply ventilation rates can enhance air distribution robustness, improving ventilation efficiency and reducing CO2 exposure under both cooling and heating conditions. These findings also suggest the need for an optimized control logic that differs from the conventional control logic used in VAV systems. Specifically, during the heating condition of displacement ventilation, it is recommended to maintain the supply ventilation rate at a higher level to effectively mitigate the impact of occupant behavior on air quality, minimize CO2 exposure risks, and ensure a more robust and reliable indoor air distribution.
•A ventilation effectiveness measurement campaign was conducted in a living laboratory office.•CO2 concentrations were measured in the breathing zone under displacement ventilation.•The supply ventilation rate and temperature shape the office air distribution.•High supply airflow is needed to reduce CO2 exposure for displacement ventilation during heating.
The application of renewable energy technologies (RETs) in the residential building sector requires acceptance of technical solutions by key stakeholders, such as building owners, real-estate ...developers, and energy providers. The objective of this study is to identify the current status of public perceptions of RETs that are available in the Finnish market and associated influencing factors, such as perceived reliability, investment cost, payback time, and national incentives. A web-based questionnaire was disseminated to the general public in the Helsinki Metropolitan Area (n = 246). Social perceptions of building-integrated RETs were evaluated through integration of survey data and Stochastic Multicriteria Acceptability Analysis (SMAA), which was applied to analyse the robustness of the survey results. The SMAA demonstrated that Finnish residents exhibit broad acceptance of multiple options, rather than preference for a single RET. Solar technologies and ground source heat pumps were the most preferred options and evaluated as very reliable, whereas wind-based technologies and combined heat and power were ranked as the least popular. In general, respondents indicated a strong willingness to financially invest in RETs as a means to reduce their carbon footprint and preferred tax deductions as an incentive to invest in RETs.
•SMAA was utilized to analyse the results of a survey on the public perceptions of RETs for residential buildings among Finnish residents.•Solar technologies and ground source heat pumps were the most preferred options and evaluated as very reliable.•Wind-based technologies and combined heat and power were ranked as the least popular.•Respondents indicated a strong willingness to invest in RETs and were in favour of receiving financial incentives to support investment in RETs.
Already in agricultural societies issues like the efficient use of natural resources, recycling of goods and materials, and minimization of food waste were key principles. Current circular economy ...initiatives are building firmly on these same principles. Often circular economy actions concentrate on material efficiency ignoring other possible flows. This paper conceptualizes circular cities by reviewing their constraints, characteristics and connections.
Even a proper definition for a “circular city” is missing. After analyzing circular economy (CE) challenges and opportunities in cities, the paper concentrates on characteristics of circular city concepts, namely definition, transition process, target setting and circularity indicators. These are the core issues a city has to define when targeting circularity.
In addition, the paper addresses city streams, their interlinkages and boundaries which a city has to analyze when deciding about the concrete actions and means. Adequate tools are needed in this phase to analyze circular cities. Potential Nexus and expert tools were identified in the paper. The paper ends up with a synthesis of steps cities need to take when targeting circularity.
Sugarcane bagasse ash (SCBA), a biomass waste resulting from sugarcane bagasse burning for electricity production, has shown to be a viable alternative option as a partial cement replacement due to ...its chemical composition and physical properties. Besides, previous research indicates that higher curing temperature may improve the mechanical properties of mixes containing SCBA as cement replacement. However, the environmental assessment of those mixes is lacking in the literature. This study aims to understand how curing temperature impacts the Life Cycle Assessment (LCA) of SCBA as a partial replacement of cement in mortars. An LCA was performed from the extraction of the raw materials to the material production part of the life cycle, including transport. This study shows that the reduction of environmental impact when using SCBA highly depends on the curing temperature. When mortars were cured at 45 °C, the use of SCBA reduced the environmental impact of mortars two times with respect to the reduction at 21 °C (31% reduction when cured at 45 °C vs. 14% at 21 °C, with a 20% replacement). This difference is mainly related to the fact that the higher the curing temperature, the better SCBA mortars perform in terms of strength, thus, net savings of cement required to achieve a given performance are higher. Results indicate that the sustainability of SCBA utilization as a partial replacement of cement will be better when mortar is poured in hot regions or during days with higher ambient temperatures. Likewise, the advantages of using SCBA in terms of sustainability will decrease if the external temperature is low.
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