Uncertainty and Reliability of Comparison of Energetic Scenarios

Background: Comparison of scenarios that involve devices for conversion or production of energy needs energetic criteria. Energy Payback Time is a typical energetic parameter used to compare the performances of systems under specific scenarios. To discriminate between scenarios the difference of parameter values is considered. The significance of the difference makes the confidence on the result and the reliability of a comparison, it depends on the difference and its uncertainty. Objective: This paper shows and discusses how to evaluate the uncertainty of the difference of parameters, defines a target uncertainty to achieve reliable discrimination. A case study on photovoltaic scenarios is used to apply methodology, commercial modules monocrystalline Si, amorphous Si and polycrystalline Si were considered for comparison. Results: Scenarios were compared by their energy payback time. All uncertainty sources were quantified and discussed and energy payback time uncertainty was calculated. Confidence of comparisons was lower than 95% and a target uncertainty was calculated. Conclusion: The use of uncertainty approach gives a much more detailed information on comparison. Confidence is the reliability of the comparison. Uncertainty analysis identify the opportunities to reduce uncertainty and enhance confidence in comparison result

The Recycling and Reuse of Natural Materials: Sound Absorbing Box Patterns That Use Waste from Olive Tree Pruning

The agricultural activity of pruning olive trees generates waste which, due to long-standing practices and unawareness of the consequences, are burned on site, thereby producing CO2 emissions in the atmosphere. Therefore, in order to prevent environmental pollution and a waste of resources, the aim of this research investigation was to highlight some alternative uses of the pruning of olive trees waste. This work focuses on recycled and reused by-products as a secondary raw material for the implementation of interior components that can be used for indoor acoustic correction purposes and evaluates their potential as absorbing materials, without overlooking the aesthetic dimension. In this paper, different configurations based on plywood frames with loose olive pruning chips used as a filler, namely, modules and sub-modules, were investigated. Moreover, other technological details, that is, the influence of a Tissue-Non-Tissue (TNT) layer and a spray film coating applied over the external surface of the loose material, were measured. Sound absorption measurements were conducted inside a small-scale reverberation room (SSRR) and the experimental results demonstrated that the samples, for the given thickness, have weighted sound absorption values (alpha(w)) of between 0.15 and 0.35 and single third-octave band values that can reach higher values than 0.50 above 500 Hz. The frequency curves and weighted values of the samples in which the influence of TNT and the spray film coating were tested remained unchanged. This is a design aspect that allows absorbing surfaces to be modeled and integrated with existing walls, while maintaining the acoustic performance and the specific aesthetic features of the loose material

Characterization of a hybrid nano-silica waterborne polyurethane coating for clay bricks

A transparent hybrid organic–inorganic waterborne coating was evaluated for the protection of clay bricks. The nanocomposite film was prepared by combining an environmentally friendly process based on UV-curing of water-based acrylic resins and a mild thermal treatment to form nanosilica in situ from alkoxysilane precursors. Coated and uncoated facing bricks were compared by scanning electron microscopy, surface profilometry, water wettability, and capillary rise tests. The hybrid coatings act as a moderate water repellent; interestingly, no appreciable alteration of the aesthetic properties of the brick was observed, in particular no gloss or color change appeared after the treatment

Photobioreactors as a Dynamic Shading System Conceived for an Outdoor Workspace of the State Library of Queensland in Brisbane: Study of Daylighting Performances

In the field of responsive shading systems, the use of photobioreactors (PBRs) containing microalgae seems to be a promising technology. Within this framework, this paper presents a case study where a PBR was specifically conceived as a shading system for an external workspace located on an open terrace of the State Library of Queensland (SLQ) in Brisbane. The proposed shading system makes use of PBRs as translucent screening elements, capable of regulating natural light to provide adequate visual comfort for a multi-purpose workspace, despite exposure of the site to direct sunlight and fluctuating weather conditions. The microalgae (Scenedesmus Obliquus) cultivated within the shading elements contribute to improving the environment by bio-sequestrating CO2 and producing oxygen. They are also a valuable raw material containing bioactive compounds with various applications including nutraceutical products, livestock feed, and biofuel synthesis. In addition, their green pigmentation is visually engaging and allows for the filtration of solar radiation. The paper focuses on analyzing the daylight performance in the outdoor workplace under the PBR shade. The biomass density of the PBR is adjustable across a wide range of light transmittances (10%-80%) to counter the highly variable outdoor conditions. For different Tv values, illuminance values were calculated using the simulation tool DIVA-for-Rhino and then analyzed as both point-in-time illuminance in June, September and December, and through climate-based daylight metrics such as the Daylight Autonomy and the Useful Daylight Illuminance. As a further step, the daylighting performances were compared to two other climates (Turin, Italy, and Dubai, United Arab Emirates), to verify which setting of the PBR may be suitable for different boundary conditions, thus making the system more widely applicable. The results in Brisbane showed that for clear sky conditions, higher levels of biomass saturation are needed (Tv < 20%) to remain in the 300-3000 lx 'optimal' illuminance comfort range, with lower concentrations (Tv < 30%) to remain within the 300-6000 lx 'acceptable' illuminance comfort range. Differently, in overcast sky conditions, the optimal range of illuminance is easily obtained with reduced levels of biomass saturation (Tv < 80%)

A Novel Photo-bioreactor Application for Microalgae Production as a Shading System in Buildings

The optical performances of plastic bag photo-bioreactors for microalgae production as shading systems for windows were assessed. The micro-algal growth rate and the light transmittance of prototypes were monitored in a photo-incubator and in a real room. Daylight in the room with algae and the energy demand for lighting EDl were then simulated using Daysim and compared to the case of a traditional venetian blind, for two different Italian sites (Turin, Palermo) and 3 orientations (south, west, north). It was found that the algae-system resulted in increased daylight level and glare and in decreased EDl

A Preliminary Study on Light Transmittance Properties of Translucent Concrete Panels with Coarse Waste Glass Inclusions

This paper investigates the potential reuse of coarse glass wastes as insert in a high performance cement matrix to produce translucent concrete panels for architectural applications such as interior walls. The effects of the addition of glass scraps on chemical and optical properties of concrete were studied. Alkali-silica reactivity resistance tests were carried out to evaluate the reactivity between amorphous waste glass and alkaline concrete pore solution. Light transmittance LT was evaluated through Radiance simulations and measurements on sample prototypes. The increase in the amount of daylight in a sample room and the reduction in the energy demand for lighting EDl were investigated through Daysim simulations. Compared to two opaque side walls, the use of two translucent concrete walls with a LT of 5% allowed a reduction in EDl up to 16% in Palermo (L=38.3°N)

Life Cycle Assessment (LCA): New poplar clones allow an environmentally sustainable cultivation

In Italy 72 poplar clones ( Populus spp.) are registered for commercialization. They were selected for fast growth, stem shape and disease resistance. The new selections (named MSA) includes genotypes with very high resistance to all the main diseases and to one insect, Phloeomizus passerinii (Sign.). Fast growth and disease resistance allow to produce wood with low environmental and economic costs; for this reason in some Italian Regions the introduction of a percentage of these clones in poplar stand is mandatory to obtain funding for their establishment (Rural Development Plan). To better understand the environmental advantages deriving from the use of these clones, in comparison with the old genotypes (particularly ‘I-214’), a ‘Life Cycle Assessment’ approach was applied considering as impact indicator the CO 2 equivalent emissions; from stoolbed to commercial stand, primary data were collected from an Italian experience. Firstly with the Inventory Analysis all the raw material, energy, wastes and emissions related were collected for each cultivation phase. The Analysis showed a reduction of 9% of CO 2 eq. ha -1 emitted, growing MSA instead of ‘I-214’. Considering the emissions per volume of wood, ‘I-214’ requests 47.5 kg CO 2 eq. per m 3 , compared with MSA that request 36.6 kg CO 2 eq. per m 3