Identification of cost-optimal and NZEB refurbishment levels for representative climates and building typologies across Europe

Abstract

The energy consumptions of the building stock are playing a central role in the energy policy of the European Union. While the Member States are applying the Directives in force, the European Commission is working to update the regulatory framework. Specifically, it is necessary to achieve the great unrealized potential for energy savings in existing buildings. With this aim, the nearly zero-energy building (NZEB) target was introduced, and a comparative methodology framework to calculate cost-optimal levels of minimum energy performance requirements was proposed. This study focuses on the issue of building renovation, and it presents the results obtained with the application of a cost-optimal calculation method for identifying proper retrofit measures to reach costoptimal levels and NZEB levels. The assessment takes into account an exhaustive set of passive and active renovation options and it was extended to various building types of 60s-70s (residential and non-residential) in a wide range of representative European climatic conditions. A very relevant energy-saving potential was found for all cost-optimal benchmarks, and in many cases, the obtained NZEB refurbishments have resulted interesting also from an economic point of view.

Yearly operational performance of a nZEB in the Mediterranean climate

“…a full on-site use of the PV generated energy), at least during the summer months. In order to understand if this solution may have a reasonable payback time, and a sound technical value, a Life Cycle cost/benefit analysis should be performed, considering different kinds of commercial solutions and battery sizes, for example using the Cost-optimal methodology of the European Union [56], where a reference building is identified (in this case the current building condition) and a set of technical solutions is applied to it, evaluating their effect both in terms of energy performance and cost. The cost-optimal level is defined as "the energy performance level which leads to the lowest cost during the estimated economic lifecycle", and it should take into account a range of costs including investments, maintenance, operating costs and energy savings [57].…”

Coste óptimo y viabilidad económica de la rehabilitación energética de viviendas en España

“…Bajo la misma metodología, otros estudios analizan un amplio espectro de tipologías de edificios, para climas representativos de Europa e, incluso, consideran edificios de consumo casi nulo NZEB (Zangheri, Armani, Pietrobon y Pagliano, 2018), en Italia (Corrado, Ballarini y Paduos, 2014) o incluyendo otros usos como oficinas (Arumägi, Simson, Kuusk, Kalamees y Kurnitski, 2017) o educacional (Niemelä, Kosonen y Jokisalo, 2016).…”

Cost optimal analysis of energy refurbishment actions depending on the local climate and its variations

“…The updating proposal of the EU Directive 2010/31/EU underlines the importance of cyclically revising the procedures for calculating energy performance, as well as the results achieved through their application, based on a constant monitoring action [6] Studies on the cost-optimal and nZEB refurbishment levels have been performed referring to representative climates, identifying reference targets and technical solutions that can guide the development of new energy requirements and targeted policies, such as in [7]. However, there is a diffuse absence of indications about the quality of input climatic data and the reference values updating to take into account the climate variations.…”