Application of hourly dynamic method for nZEB buildings in Italian context: analysis and comparisons in national calculation procedure framework

The Energy Performance of Buildings Directive (EPBD 2018/844/EU) requires to Member States to upgrade the methodology for the energy performance assessment of buildings. The current calculation method, based on the monthly quasi steady state calculation procedure, could be replaced in the next years by an hourly dynamic calculation procedure (EN ISO 52016), in which a resistance-capacity (RC) model is implemented to consider with more accuracy the heat exchange through the building envelope. In this framework, the present work aims at analysing and comparing the energy needs of three reference case studies of nearly Zero Energy Buildings (nZEB), applying both calculation procedures in order to investigate the main difference of the two approaches. Two residential buildings and one office, compliant with Italian minimum requirements for nZEB, were defined, and several energy simulations were carried out for all different climatic zones of Italian territory. Preliminary results highlighted significant differences of energy need mainly due to different weight of heat loss and heat gains obtained with the two considered calculation methods. This paper represents a preliminary study, but further analysis are recommended in order to evaluate the overall energy use for different type and different operation profile of buildings

Field study on heat pump monitoring: challenges and opportunities

In view of the decarbonisation targets in the building sector, heat pump can play a key role, marking the shift towards all-electric buildings. Although the heat pump technology is well known, and its use is ever increasing, some issues (practical and operative) are still open in the assessment of the main aspects that influence the efficiency. These complexities emerge when heat pump monitoring is carried out, allowing to assess the real performance. Therefore, in this work, the challenges and opportunities of heat pump monitoring are presented, from a field study of the tertiary sector. The monitoring of an air-to-water heat pump allowed to: (i) assess its real operating performance; (ii) compare the correlations of results with climate data and load profile; (iii) highlight some critical points, as the importance of data mining and data cleaning phase for the reliability of the results; (iv) assess and identify which is the temporal scale needed for a proper data elaboration

impact of different luminous efficacy models on the calculation of lighting energy uses in non residential buildings

Abstract Artificial lighting has a relevant impact on the electricity uses in non-residential buildings. The calculation method introduced in the relevant EN standards takes into account, only to some extent, the daylighting role on the lighting performances of buildings. An alternative method is under development for the Italian territory, which introduces a climate based approach to properly estimate the day light contribution. The method requires the implementation outdoor global and diffuse illuminance Typical Meteorogical Years (TMY), which calculated starting from solar irradiation data and luminous efficacy models. Different models can be used for this purpose, consequently these differences may lead to different estimates of daylight availability in buildings during the year. This paper explores the impact of different luminous efficacy models on the lighting energy uses in non-residential buildings. A typical office building is used for the study and calculations are carried out for three localities of the Italian territory. The outdoor luminous environment, the reference indoor visual task and the building daylight characteristics are taken into account. Results allow to compare the energy lighting performance of the building applying the different luminous efficacy models and, as a consequence, to select the most suitable model to be used in a climate based artificial lighting calculation method

Impact of Different Illuminance Typical Years Models on a Climate Based Method for the Calculation of Artificial Lighting Energy Use in Office Buildings

Artificial lighting has a relevant impact on the electricity uses in not residential buildings. The method to assess such uses is based on standards, which hardly take into account the daylighting contribution and the time evolution of the outdoor illuminance conditions. Different models were adopted to build diffuse illuminance reference years, starting from satellite images. These models lead to different daylight availability during the year. The paper explores the impact that these models have on the artificial lighting energy uses by hourly monthly mean calculations. The test was carried out with a climate based method, which takes into account: the outdoor luminous environment, the reference indoor visual task and the building daylight characteristics. A typical office building was used for the test in Rome, Italy. Results allowed to compare the impact of each model and to select the most suitable one to be implemented in the climate based method to predict artificial lighting use in buildings

An Alternative Method for the Assessment of the Typical Lighting Energy Numeric Indicator for Different Outdoor Illuminance Conditions.

The contribution of daylight plays a key role in the evaluation of the Lighting Energy Numeric Indicator (LENI), which refers to the annual lighting energy consumption per square meter: the higher the contribution, the lower the energy consumption. Calculation of energy need for artificial lighting is defined in European Standard EN 15193-1:2017; the daylight availability is assessed by using the Daylight Factor. This parameter is easy to use and commonly applied by designers and technicians, but it has several limitations. The estimation of daylight contribution proposed in the first version of the EN 15193:2008 was discussed in literature and alternative methodologies and models have been suggested, since it was noticed that it underestimated the daylight contribution. Starting from these considerations, this study will focus on the analysis of a parameter which represents a middle way between static and climate-based variables. This new variable is the Daylight Factor Target, reference parameter of the new EN 17037. The D target will be used in the alternative methodology of LENI calculation developed in previous studies and the results will be compared with the ones obtained by applying the EN 15193-1:2017 procedure. Results showed that the Daylight Factor Target allows to assess in the first building design phase the LENI of any building which complies with the EN 17037, independently from its characteristics, just choosing the operative working hours and the lighting power installed. The LENI target resulted to be 50% lower than the values obtained using EN 15193-1:2017