Search

Ubiquitous street lighting is essential for urban areas. While nowadays, LED-based “smart lamps” are commercially available, municipalities can only switch to them in the long run due to financial constraints. Especially, older types of lamps require frequent bulb replacements to maintain the lighting infrastructure’s function. To speed up the detection of defects and enable better planning, a non-invasively retrofittable IoT sensor solution is proposed that monitors lamps for defects via visible light sensors, communicates measurement data wirelessly to a central location via LoRaWAN, and processes and visualizes the resulting information centrally. The sensor nodes are capable of automatically adjusting to shifting day- and nighttimes thanks to a second sensor monitoring ambient light. The work specifically addresses aspects of energy efficiency essential to the battery-powered operation of the sensor nodes. Besides design considerations and implementation details, the paper also summarizes the experimental validation of the system by way of an extensive field trial and expounds upon further experiences from it.

Ubiquitous street lighting is essential for urban areas. While nowadays, LED-based "smart lamps" are commercially available, municipalities can only switch to them in the long run due to financial constraints. Especially, older types of lamps require frequent bulb replacements to maintain the lighting infrastructure's function. To speed up the detection of defects and enable better planning, a non-invasively retrofittable IoT sensor solution is proposed that monitors lamps for defects via visible light sensors, communicates measurement data wirelessly to a central location via LoRaWAN, and processes and visualizes the resulting information centrally. The sensor nodes are capable of automatically adjusting to shifting day- and nighttimes thanks to a second sensor monitoring ambient light. The work specifically addresses aspects of energy efficiency essential to the battery-powered operation of the sensor nodes. Besides design considerations and implementation details, the paper also summarizes the experimental validation of the system by way of an extensive field trial and expounds upon further experiences from it. [ABSTRACT FROM AUTHOR]

Precast reinforced concrete building structures are widely used in the Portuguese industrial stock and throughout Europe. Beam-to-column connections are a key component in this type of structure. However, they are also the source of significant damage, as reported in recent earthquakes. Different configurations are common, such as using a dowel, neoprene or just assuming a concrete-to-concrete interface. Both are characterized by a low deformation and strength capacity, presenting a significant vulnerability against seismic actions. Based on this motivation, a novel low-cost and easy-to-apply retrofit connection is herein proposed to reduce this vulnerability. Shear tests were performed to compare the performance of a retrofitted connection with the as-built configuration (i.e. concrete-neoprene interface). The experimental tests showed a good performance of the proposed retrofit solution, emphasizing the importance of this solution in frictional connections to control horizontal displacements. With the use of this solution, it was possible to overcome the resistance obtained in the connections with dowels in the most vulnerable direction, obtaining a 49% increase in the lateral resistance in the most vulnerable direction (loss of support of the beam on the column) concerning that which was verified in the friction-only connection. • The work addressed the vulnerability of precast RC beam-to-column connections. • A novel retrofit connection was proposed to enhance the deformation and strength capacity of precast RC connections. • The solution aimed to be low-cost and easy to apply. • The retrofitted specimens exhibited no damage in the beam and column, successfully protecting the reinforced concrete elements. • The retrofitting solution significantly increased the stiffness and strength in the pull direction. [ABSTRACT FROM AUTHOR]

The usage of renewable energy sources (RESs) with energy storage like battery and so on in the stand‐alone household and commercial purpose is becoming popular. These systems have to manage the requirement with the generated energy from the RES. Further, in a typical stand‐alone household application, a significant amount of power is consumed by single‐phase induction motor (SPIM) fans in the form of the ceiling, pedestal formats. So, it is necessary to save energy by operating them efficiently and economically in a stand‐alone system. This study proposes a fractional flux‐based V/f control strategy for speed control of a SPIM. The proposed retrofit scheme is simple and is easy to implement. It minimises the magnetisation loss irrespective of the fan speed and also saves nearly 10–20% of power consumption as compared to the conventional voltage control method. Further, in this study, a new performance parameter is defined which helps in determining an economic zone in variable speed operation SPIM. In this economic zone of operation, a particular battery can deliver power for an extended time. All the details with respect to analysis, modelling, simulation and experimental results to support the proposed strategy are presented in this study. [ABSTRACT FROM AUTHOR]

• Thermal performance of the proposed hot water storage was evaluated experimentally. • Proposed solution shows a 19% less total thermal loss than the centralised system. • Circulating pump in this solution consumes 11 times lower energy than centralised one. • The LCC of proposed solution is 6.1% lower than that of the centralised system. • Centralised system requires higher operating costs but a lower control system cost. The retrofit solution for domestic hot water (DHW) system in existing buildings requires to ensure the long-term energy security and efficiency as well as to minimise occupants' disturbance, construction works and installation costs. In this regard, the present study performs a techno-economic evaluation on a novel retrofit solution for DHW production in a pilot building. The proposed solution appoints a substantial role to the thermal energy storage through a 2-pipe hot water network utilisable for both DHW and heating purposes. The first storage level is provided by a centralised buffer storage supplied by a PV-BESS-driven heat pump while the second level consists of decentralised modular tanks installed in each dwelling for the production and storage of hot water. Firstly, experimental thermal performance of the proposed decentralised storages is investigated. By developing a dynamic simulation code, the energy efficiency of the proposed solution is compared to that of the existing system in the pilot building as well to that of a typical centralised system as a benchmark solution. Finally, economic analysis of the retrofit solution is performed to address capital expenditures of the system, including purchasing and installation costs, as well as its life cycle cost (LCC). The obtained results indicate that the proposed system reduces the annual energy consumption for DHW production more than 7,200 kWh, with respect to the existing DHW system. Furthermore, it is shown that, in the proposed system, the fraction of thermal loss from piping network decreases by 31.5%, compared to a typical DHW centralised system. Economic assessment of the proposed solution implies that this system, in terms of both mechanical and electrical components, requires 13.7% lower initial investment than a typical centralised system. However, the cost of control systems in this system is higher since it is inherently a control-based system. [ABSTRACT FROM AUTHOR]

Optimizing consumptions in the field of civil construction led to define energy labels for residential buildings. To calculate the building energy demand the EPgl was determined, i.e. the annual consumption per m 2 of primary energy. This paper examines the technical solutions useful to optimize the energy demands for heating during space-heating season and domestic hot water production (thanks to energy analysis softwares as MC11300 and TRNSYS) and, at the same time, to take into account the financial issues those interventions implied. The total inside heated surface of the building case study is 1204.00 m 2 , hence the inside heated volume is about 3250.80 m 3 . Besides the more traditional interventions concerning the building envelope and its systems, the paper examined the performance of a system obtained through the combination of a cogenerator (CHP) and a heat pump (HP), thus, substituting the conventional boilers of the buildings. CHP+HP solution increases the most the energy label of the building (from a D class with EPgl = 59.62 kW h m −2 year −1 , to an A class, with EPgl = 25.64 kW h m −2 year −1 ), determining an annual energy cost saving of 3,114 € year −1 , allowing to amortize installation costs (54,560 €) in a reasonable payback period, i.e. 15.4 years. This innovative solution in the residential sector can be realized through retrofit interventions on existing buildings, hence it leads the current dwelling towards nZEB with a remarkable benefits for the environment. [ABSTRACT FROM AUTHOR]

Carbon dioxide ( CO2) sensors that provide a visual indication were installed in classrooms during normal school operation. During 2-week periods, teachers and students were instructed to open the windows in response to the visual CO2 feedback in 1 week and open them, as they would normally do, without visual feedback, in the other week. In the heating season, two pairs of classrooms were monitored, one pair naturally and the other pair mechanically ventilated. In the cooling season, two pairs of naturally ventilated classrooms were monitored, one pair with split cooling in operation and the other pair with no cooling. Classrooms were matched by grade. Providing visual CO2 feedback reduced CO2 levels, as more windows were opened in this condition. This increased energy use for heating and reduced the cooling requirement in summertime. Split cooling reduced the frequency of window opening only when no visual CO2 feedback was present. [ABSTRACT FROM AUTHOR]

The all-dielectric self-supporting (ADSS) cable offers many advantages when installing an optical fiber network on high-voltage overhead lines. Generally, the use of ADSS cables is confined to system voltage levels well below 275 kV because of the threat of dry-band arcing on the cable sheath. This limit is somewhat arbitrary since, in polluted conditions, cables can fail at much lower system voltages, and in some higher voltage installations no problems have been witnessed. A solution to the problem of dry-band arcing on ADSS cables has been proposed previously, where 50-m resistive rods are attached to the self-supporting cable after installation. The first large-scale installation of this system has been successful, and the first six years of operation is reviewed. The installation is in a particularly aggressive situation and a high level of maintenance has been found to be necessary. [ABSTRACT FROM AUTHOR]