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A novel methodology for optimizing thermal storage for biomass boiler heating systems is presented in this paper. Biomass boiler heating systems have gradually gained popularity in residential, commercial, and large-scale district heating plants due to the lower carbon footprint of biomass energy. One unanswered question in this field was the size of the thermal energy storage (TES) tank with respect to different boiler capacities and different types of heat demand profiles. Different standards and recommendations (based only on boiler capacities) have been proposed by various organizations around the world with large deviations on the sizing of the TES tank, but without a clear technical basis for these recommendations. These inconsistencies impede the effective design and deployment of biomass boiler heating systems. This study used a dynamic process simulation system based on field data from a 25-kW wood pellet boiler with radiant floor heating. By running the simulation for different boiler capacities (N) and different types of heat demand profiles (i.e. low, medium, high, intermittent, and variable), the optimum TES tank volume can be estimated by evaluating the TES tank discharge efficiency, boiler on-time, boiler off-time, and maximum boiler output temperature. Linear correlations between optimum TES tank volume and boiler nominal capacity for different types of heat demand profiles were obtained. The results showed that the medium building heat demand (45% N) required the smallest TES tank volume while intermittent building demand requires the largest. High building demand (60% N) generates the highest TES tank discharge efficiency (up to 99%) but also requires large storage volume. From the economic point of view, it is recommended to size the thermal energy storage system such that the average building heat demand is around 45% of boiler nominal capacity. [ABSTRACT FROM AUTHOR]

• An innovative slim decentralised plug-and-play tank is proposed for DHW production. • Model calibration is performed by experimental data in charge/discharge process. • Retrofit solution cuts required annual energy in half of which 82% is RES quota. • Optimised charging scheme reduces the total annual electrical energy by 5.2 %. • A degree increment in draw-off temperature increases annual CO 2 emission by 103 kg. The present study deals with a multi-objective analysis of an innovative decentralised system to produce and store domestic hot water (DHW), emphasising on the combined effects of the technological aspect, control strategy and user's behaviour. The proposed system, by relying on thermal energy storage, decouples energy production and demand while shaves peaks in the energy demand and, at the same time, provides more autonomy to users through local storages. To identify subtle interactions in components of DHW system, dynamic simulations are carried out by establishing a coupled TRNSYS-MATLAB code, calibrated and validated by experimental measurements. The energy analysis implies that the proposed system cuts the required annual electrical energy in half, of which up to 82% of needed primary energy is supplied from renewable sources, compared to previous electrical-decentralised system. The optimisation of the results through applying control strategies indicates that adopting a three-time charging scheme is advantageous in terms of providing a more stable temperature profile as well as a higher hot water temperature. Compared to an available-by-demand operation, this scheme reduces the required total annual electricity by 5.2 % and enhances total thermal loss from components up to 4.0%. Furthermore, a sensitivity analysis on the results emphasises the striking role of the user behaviour in electrical energy consumption either via draw-off temperature or adjusting the pre-defined temperature for activation of the built-in auxiliary heater. [ABSTRACT FROM AUTHOR]

The capability to dynamically plan, predict, and control indoor conditioning allows to adapt to individual preferences of inhabitants and enables demand side management. While former mainly improves thermal comfort of inhabitants so does latter unlock ecological and financial opportunities mostly for energy utilities. Commonly, dynamic indoor conditioning is based on piece-wise constant indoor temperature constraints. This paper's contribution is the presentation of additional constraints: in particular ones expressed relative to the nominal behavior of a hydronic heating system. This allows to simultaneously harness the relevant process variables in particular during the pre-loading and post-loading phases of a load reduction. The findings are based on data sets acquired on 10 inhabited, residential buildings in Stockholm over a whole year. One of the findings is that building models need to be adaptable if predictive control is applied in practice. This adaptability is assured by a novel concept, i.e. a so called model manager on which the control is relying for the selection of the most accurate model. Centralized optimal control of buildings connected to a district heating network is challenging in practice due to a high computational load. In order to reduce it, the herein presented method elaborates plans only every hour instead of at every control step for optimal control. Since these plans cannot be optimal due to the lack of regular update a hitherto unknown cascaded control logic has been developed that corrects planning errors and other disturbances. Capabilities are demonstrated and compared to conventional controllers in dynamic simulations of a multi-zoned building. The herein presented method is to our knowledge the first to provide all flexibility desired by energy utilities and inhabitants alike through harnessing the consequences of transitions. [ABSTRACT FROM AUTHOR]

Using of Double Skin Facade (DSF) became a very demanding trend in most kind of buildings, since it provides natural light, creates a connection between indoor inhabitants and the external environment without getting affected by harsh weather conditions. The verification of the balance equations to be used in a dynamic simulation software and the assessment of the active double-skin facade thermal performance in terms of energy recovery savings are the two main items of this study. For this purpose the software DIGITHON has been used. By comparing measured data of exit air temperature from a certain facade with calculated results, validation has been attained to use it in terms of buildings integrated with DSF. Highlighting benefits of using facade as a thermal energy recovery item during heating seasons on HVAC system is presented with respect to four European climatic zones for each orientation. Average pre-heat efficiency has been studied and illustrated on a seasonal scale. [ABSTRACT FROM AUTHOR]

Abstract: The paper suggests a multi-criteria approach for the energy refurbishment of historical buildings, proposing methodologies for the performance analysis, coupling several experimental and numerical studies. The target consisted in a rigorous evaluation procedure, in order to guarantee the necessary reliability of a numerical model of the system “building envelope/technical plants”, on which testing the technical and economical convenience of energy retrofit solutions. The paper collects the long work carried out by several Institutions during the last years, on Building “Palazzo dell’Aquila Bosco-Lucarelli”, a historical building located in Benevento (Southern Italy), currently analyzed in order to define the technical adoption of possible improving actions. The carried out studies, beyond the proposition of an operational methodology, are aimed to evidence a best-practice specified for the Italian territorial context, which has several historical buildings needing restoration. Carefully applied investigations, based on various methodologies and through several instrumentations, allowed the definition of a numerical model correspondent to the real building, defined also comparing the results with the historical requests of gas and electricity. Moreover, dynamic energy simulations tested the effectiveness, singularly and coupled, of several solutions for the building energy optimization. A significant potentiality of energy and economic optimization has been demonstrated. [Copyright &y& Elsevier]