Cost-Optimal measures for renovation of existing school buildings towards nZEB

Abstract The energy policies of the European Union (EU) encourage the member states to convert building stock into nearly Zero-Energy Buildings (nZEB) and national public authorities to adopt exemplary actions. Directive 2010/31/EU (EPBD recast) introduces the concept of nZEB as a building that has a very high energy performance and its energy need is covered to a very significant extent by energy from renewable sources (RES). Moreover the Directive refers to the cost-optimal methodology for fixing building energy requirements. This paper presents the results of the application of the cost-optimal methodology in a couple of existing school buildings located in the North East of Italy. The analysed buildings are a primary and a secondary schools that differ in construction period, in compactness ratio, in buildings envelope materials and systems. Several combinations of retrofit measures have been applied in order to derive cost-effective efficient solutions for retrofitting according to the methodology proposed by the project Annex56 "Cost Effective Energy & CO2 Emissions Optimization in Building Renovation". The cost-optimal level has been identified for each building and the best performing solutions have been selected considering a financial analysis and the application of "Conto Termico 2.0" government incentives. The results show the suitability of the proposed methodology to assess cost-optimality and energy efficiency in school building refurbishment. Moreover, this study shows different possibility providing the most cost-effective balance between costs and energy saving

Spectrally Resolved Single-Photon Timing of Silicon Photomultipliers for Time-Domain Diffuse Spectroscopy

We characterized the single-photon timing response function of various silicon photomultipliers (SiPMs) over a broad (500-1100 nm) spectral range. We selected two SiPM manufacturers, and we investigated two active areas, i.e., a small (1-1.69 mm2 and a large (9 mm2) one, for each of them. We demonstrate that selected SiPMs are suitable for time-resolved diffuse optics (DO) applications where a very large detection area and sensitivity down to single photons are crucial to detecting the very faint return signal from biological tissues, like the brain, thus allowing replacement of photomultiplier tubes and opening the way to a novel generation of DO multichannel instrumentation. Due to our custom front-end electronics, we show the world's best single-photon timing resolution for SiPMs, namely, 57-ps full-width at half maximum for Hamamatsu 1.69 mm2 and 115 ps for Excelitas 9 mm2. Even further, we provide a thorough spectral investigation of the full single-photon timing response function, also detailing diffusion tails' time constants and dynamic range. The achieved insight and the reported performance open the way to a widespread diffusion of SiPMs not just in many-photon regimes (e.g., PET) but at single-photon counting regimes like DO as well

Novel approaches to photon detection and timing for 7-wavelength time domain optical mammography

An 8-channel Silicon Photomultiplier probe and a Time-to-Digital Converter are used to build a higher-throughput, cheaper and compact detection chain for time-resolved optical mammography as compared with conventional PhotoMultiplier Tubes and Time-Correlated Single-Photon Counting boards, still providing comparable performance in the estimation of optical properties, but with higher optical responsivity

Time-resolved single-photon detection module based on silicon photomultiplier: A novel building block for time-correlated measurement systems

We present the design and preliminary characterization of the first detection module based on Silicon Photomultiplier (SiPM) tailored for single-photon timing applications. The aim of this work is to demonstrate, thanks to the design of a suitable module, the possibility to easily exploit SiPM in many applications as an interesting detector featuring large active area, similarly to photomultipliers tubes, but keeping the advantages of solid state detectors (high quantum efficiency, low cost, compactness, robustness, low bias voltage, and insensitiveness to magnetic field). The module integrates a cooled SiPM with a total photosensitive area of 1 mm2 together with the suitable avalanche signal read-out circuit, the signal conditioning, the biasing electronics, and a Peltier cooler driver for thermal stabilization. It is able to extract the single-photon timing information with resolution better than 100 ps full-width at half maximum. We verified the effective stabilization in response to external thermal perturbations, thus proving the complete insensitivity of the module to environment temperature variations, which represents a fundamental parameter to profitably use the instrument for real-field applications. We also characterized the single-photon timing resolution, the background noise due to both primary dark count generation and afterpulsing, the single-photon detection efficiency, and the instrument response function shape. The proposed module can become a reliable and cost-effective building block for time-correlated single-photon counting instruments in applications requiring high collection capability of isotropic light and detection efficiency (e.g., fluorescence decay measurements or time-domain diffuse optics systems)

A bottom-up methodology for buildings energy demand calculation to support grid based energy systems in urban areas

The aim of the project IDEE is the development of a standard and shared procedure to support the evaluation of the better network energy system – based on centralized renewable energy plants or on heat recovered from energy loss – to be adopted at urban scale. The choice of the best solutions is affected by three main aspects: energy demand (amount of energy to be delivered to the buildings); energy supply (amount of energy that is possible to be recovered from industrial areas or centralized renewable energy power plants); district heating network configuration (distance from supply point to buildings, shape of network, …). In this paper, the focus is on the definition of a methodology and relative protocols for the calculation of energy demand of all buildings of a given urban environment

Analog SiPM in Planar CMOS Technology

Silicon Photomultipliers (SiPMs) are emerging single photon detectors used in many applications requiring large active area, photon number resolving capability and immunity to magnetic fields. We developed planar analog SiPMs in a reliable and cost-effective CMOS technology with a total photosensitive area of about 1×1 mm2. Three devices with different active areas, and fill-factor (21%, 58.3%, 73.7%), have been characterized. The maximum photon detection efficiency is in the near-UV and tops at 38% (fill-factor included), with a dark count rate of 125 kcps. Gain and crosstalk depend on the active area size and are comparable to those of commercial best-in-class custom-technology SiPMs. However our full CMOS processing enables advanced SiPM single-chip systems where transistors and further on chip electronics can be integrated together with the detectors

Large area silicon photomultipliers allow extreme depth penetration in time-domain diffuse optics

We present the design of a novel single-photon timing module, based on a Silicon Photomultiplier (SiPM) featuring a collection area of 9 mm2. The module performs Single-Photon Timing Resolution of about 140 ps, thus being suitable for diffuse optics application. The small size of the instrument (5 cm × 4 cm × 10 cm) allows placing it directly in contact with the sample under investigation, maximizing that way the signal harvesting. Thanks to that, it is possible to increase the source detector distance up to 6 cm or more, therefore enhancing the penetration depth up to an impressive value of 4 cm and paving the way to the exploration of the deepest human body structures in a completely non-invasive approach

Evaluation of a pipeline for simulation, reconstruction, and classification in ultrasound-aided diffuse optical tomography of breast tumors

SIGNIFICANCE: Diffuse optical tomography is an ill-posed problem. Combination with ultrasound can improve the results of diffuse optical tomography applied to the diagnosis of breast cancer and allow for classification of lesions. AIM: To provide a simulation pipeline for the assessment of reconstruction and classification methods for diffuse optical tomography with concurrent ultrasound information. APPROACH: A set of breast digital phantoms with benign and malignant lesions was simulated building on the software VICTRE. Acoustic and optical properties were assigned to the phantoms for the generation of B-mode images and optical data. A reconstruction algorithm based on a two-region nonlinear fitting and incorporating the ultrasound information was tested. Machine learning classification methods were applied to the reconstructed values to discriminate lesions into benign and malignant after reconstruction. RESULTS: The approach allowed us to generate realistic US and optical data and to test a two-region reconstruction method for a large number of realistic simulations. When information is extracted from ultrasound images, at least 75% of lesions are correctly classified. With ideal two-region separation, the accuracy is higher than 80%. CONCLUSIONS: A pipeline for the generation of realistic ultrasound and diffuse optics data was implemented. Machine learning methods applied to a optical reconstruction with a nonlinear optical model and morphological information permit to discriminate malignant lesions from benign ones

Pushing Time-Domain Diffuse Optics to Its Ultimate Limits: New Large-Area Detector and Operation Modality

Large area single-photon detectors enhance light harvesting capability beyond state-ofthe-art provided that pile-up distortion is corrected. We test a 10 × 10 mm2 SiPM-based detector and study the possibility to work beyond singe-photon statistics

Novel time-resolved camera based on compressed sensing

Time-resolved cameras with high temporal resolution (down to ps) enable a huge set of novel applications ranging from biomedicine and environmental science to material and device characterization. In this work, we propose, and experimentally validate, a novel detection scheme for time-resolved imaging based on a compressed sampling approach. The proposed scheme unifies into a single element all the required operations, i.e. space modulation, space integration and time-resolved detection, paving the way to dramatic cost reduction, performance improvement and ease of use