New Calculation Method

The EU Directive 2010/31 abstained from prescribing harmonized and strict requirements for nearly Zero Energy Buildings (nZEBs), to provide EU countries flexibility and room for maneuver in setting national targets, in view of the impact of local climatic conditions and specific territorial and socio-economical features on heating and cooling needs. Benchmarks are usually provided in terms of primary energy needs, however the definition of accurate calculation methodologies, notably as regards the cooling share, is a rather challenging task. Nonetheless, its accomplishment is cardinal to countries, like Mediterranean ones, were the building performance is mostly dictated by summertime sensitivities. This paper presents a cutting-edge approach to nZEB performance analysis: the monthly quasi steady-state (EN 13790 as implemented in Italian UNI/TS 11300) and hourly dynamic calculation methods (developed under the standard UNI EN ISO 52016-1:2018) are compared, with due attention to the cooling energy consumption, to spot pros and cons of a finer temporal discretization. Potential nZEB design alternatives in three different Italian climatic zones are contemplated and used to confront the effectiveness of the above procedures. 1. Introduction Considering the tightening of global warming and the increasing occurrence of summer heat waves even in temperate climatic contexts, it is essential to tackle the design of a nearly Zero Energy Building (nZEB), that maintains high cooling performance and preserves summer comfort even under abnormal conditions [1], [2]. Despite the awareness of the international scientific community, the actions implemented by the national regulatory instruments, in response to the European Directive 2010/31/EU (EPBD recast) [3], merely aim at verifying envelope insulation and solar shadings compliance with prescribed performance indicators [4], [5], disregarding the higher degree of dynamism in summertime. The quasi steady-state calculation method of EN ISO 13790:2008 [6], gold standard for almost all EU countries today, is effective for the calculation of heating needs, but presents severe limitations in the case of cooling energy [7-12]. Also, the tools for dynamic calculation (e.g. TRNSYS and EnergyPlus) are sophisticated and still poorly used by designers, due to the considerable commitment of time and resources. In this context, newly introduced EN ISO 52016-1:2017 [13] (replacing EN ISO 13790) specifies calculation methods for the assessment of buildings energy need for heating and cooling, providing a novel simplified hourly method alongside the monthly method. The dynamic hourly method offers opportunities of great interest [14]. In fact, it is able to deliver more accurate results, without computational overload [15]. In EU countries this regulatory evolution entails the need to revise the current procedure for calculating heating and cooling needs, also in relation to nZEB.

In this work, we presented one of the applications of mathematical modeling to the cardiovascular system, its use in the estimation of the left ventricular volume, which is a basic parameter in the diagnosis of heart disease. To do that, a mold of a bovine left ventricle is prepared, its real volume is determined and then it is compared to the results achieved by medical mathematical methods and with a new proposed method, based on the integral of revolution of a specific polynomial function. Preliminary results indicate that the proposed method is more efficient than medical methods, with a difference of only 3.5% of the actual volume.

Resumo

Nesse trabalho, apresenta-se uma das aplicações da modelagem matemática no sistema cardiovascular, a sua utilização na estimação do volume ventricular esquerdo-um parâmetro fundamental no diagnóstico de doenças cardíacas. Para isso, prepara-se um molde de um ventrículo esquerdo bovino, seu volume real é determinado e, então, comparado com os resultados obtidos por métodos matemáticos médicos e com um novo método proposto, baseado na integral de revolução de uma função polinomial específica. Os resultados preliminares indicam que o método proposto é mais eficiente que os métodos médicos, com diferença de apenas 3,5% do volume real. Palavras-chave: Modelagem Matemática. Novo Método de Cálculo. Volume Ventricular.