The design of Nearly zero-energy buildings

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On the refurbishment of the public building stock toward the nearly zero-energy target: two Italian case studies

The study presents some results of the on-going European Project, RePublic_ZEB, on the refurbishment of the public building stock towards nearly Zero Energy Building (nZEB). The work is focused on the application of the nZEB requirements to two existing public buildings representative of the 1960s in Northern Italy. Many packages of energy efficiency measures that comply with nZEB requirements are identified and evaluated. The aim is to promote energy efficient but also cost-effective solutions for the Italian building stock refurbishment. The results are presented in terms of “package of measures”, energy consumption, global costs, actualized pay-back period and CO2 emission

the effect of glazing on nzeb performance

Abstract In the last decades, European countries have provided for stringent energy requirements for new buildings. In improving the energy performance of buildings, windows play a significant role as they largely influence the energy need. The windows design should base on the balanced trade-off between the solar heat gains and the heat transfer by transmission. In the paper, for some Italian climatic zones, the relation between the optimal window-to-wall ratio (WWR) and the energy need in residential nearly zero-energy buildings (nZEBs) is investigated. In the case studies, the envelope thermo-physical properties are consistent with the nZEB requirements established at national level. The energy performance assessment is carried out by means of a detailed dynamic simulation tool (EnergyPlus). The influence of different orientations and sizes of windows on the energy performance and the peak power are studied. The paper analyses the effect of WWR in the design of nZEBs

The new Italian climatic data and their effect in the calculation of the energy performance of buildings

Reference climatic data have been available since the early 90s in order to ensure uniformity of assessment and repeatability of energy performance calculations: they include monthly means of meteorological elements, as reported in national standards. Other climatic data were provided by ENEA for the period 1995-1999. More recently, new test reference years, representing the basis of UNI 10349 update, were made available by CTI. Some discrepancies between the old and the new sets of data appear. For some reference NZEBs, this paper presents the analysis of the effects of the climatic data on the calculation of energy performance of buildings

Verification of the new Ministerial Decree about minimum requirements for the energy performance of buildings

The Italian Ministerial Decree 26/06/2015 specifies the requirements of nearly zero-energy buildings (nZEBs) and demands that the energy performance of the new building is compared with that of a reference or target building, which has the same location, function, size, but reference insulation level and technical systems efficiencies. The research aims both to investigate the technical feasibility of design solutions complying with the legislative requirements and to verify the reference building approach. The analysis is applied to a residential building in three Italian climatic zones. The calculations are conducted by means of quasi-steady (UNI/TS 11300) and dynamic (Energy Plus) methods

Reference Building Approach Combined with Dynamic Simulation in Designing nZEBs

The building energy performance requirements in the regulations are usually expressed by means of a fixed value or a variable value defined through a formula or the notional reference building approach. The aim of the article is to enhance the application of the notional reference building approach in the energy performance legislation. To this purpose, a detailed dynamic simulation is performed on an Italian residential nZEB located in two different climatic zones. The paper highlights the need of more detailed specifications of the reference parameters in the notional reference building, especially when dynamic simulation is performed

The significant imbalance of nZEB energy need for heating and cooling in Italian climatic zones

Building energy performance requirements aiming at the nZEB target have been recently established by the national legislation. In Italy, the requirements are verified through the notional reference building, whose U-values are reduced in two steps: up to 2018 and since 2019 for public buildings, and up to 2020 and since 2021 for all other buildings. This might cause a reduction of the heating need but an increase of the cooling need. The objective of the study is to investigate in which conditions and extent a significant imbalance of the energy needs occurs. Different building types and climatic zones are considered

La trasformazione degli edifici pubblici in nZEB (edifici a energia quasi zero)

L’articolo presenta alcuni risultati del progetto europeo RePublic_ZEB, relativo alla ristrutturazione del patrimonio edilizio pubblico verso l’obiettivo nZEB. Il lavoro si concentra sull’applicazione della definizione di nZEB adottata nel progetto attraverso l’analisi di un edificio pubblico esistente ad uso uffici. Vengono identificati e valutati un insieme di pacchetti di misure di efficienza energetica che rispondono ai requisiti nZEB. The paper presents some results of the European Project, RePublic_ZEB, on the refurbishment of the public building stock towards the nearly zero energy target (nZEB). The work is focused on the application of the nZEB definition as adopted in the project context, to an existing public office, representative of this Italian building type in Northern Italy. A set of packages of energy efficiency measures that comply with the nZEB requirements has been identified and evaluated

Hygrothermal modelling of building enclosures: reference year design for moisture accumulation and condensation risk assessment

Interstitial condensation and water accumulation risk in building envelopes could be assessed with methods and models base d on moisture migration through porous media coupled to heat transfer. One of the difficulties in evaluating the boundary conditions for the heat and mass transfer model is the choice of an appropriate weather file. The most advanced models, described by the standard EN 15026:2007, require the hourly values of rain, wind, radiation, temperature and relative humidity to compute the water content in the porous materials. In this contribution, the method described by the standard EN ISO 15927-4:2005, typically used to design Moisture Reference Years (MRY), has been extended to the design of 34 typologies of representative weather files. The generation criteria have been base d on the assumption that the simulation results are influenced by rain deposition on the considered wall. The procedure has been followed considering 5 different wall exposures that lead to different MRY. The years of the climate of Turin (Italy) between 2002 and 2016 have been considered for the generation of the reference years. Finally, the annual mean moisture contents for two common wall types have been calculated using the obtained MRY and compared to the annual mean moisture contents obtained with the measured weather data, and the effects of the selection of the weather parameters is presented