Evaluating Cost-Optimality of High-Rise Buildings by Considering Outdoor Air Rates in TS825 Standard

1. Introduction

Buildings account for about 40% of energy consumption and 36% of greenhouse gas emissions in the European Union (EU) (EU, 2021). To enhance energy efficiency by evaluating and certifying their performance, the EU introduced the Energy Performance of Buildings Directive (EPBD) in 2002 (CEN, 2003). The EPBD-recast (EPBD 2010/31/EU), which revised the EPBD in 2010, introduced the concept of “cost-optimal energy efficiency.” It established a comparative methodological framework for determining the cost-optimal levels of minimum energy performance requirements and requires all EU member states to calculate cost-optimal energy efficiency levels for buildings. As per the Directive, the cost-optimal level refers to the energy performance level that results in the lowest cost over the estimated economic lifecycle (EU, 2018, CEN, 2010). In Fig.1, the global cost curve is illustrated which analyzes the global cost during the estimated economic lifecycle of building and annual primary energy consumption of building, simultaneously.

Figure 1.

Global cost curve (A: economic optimum, B: requirement in force, C: cost neutral compared to requirement in force, and nZEB: is a building that has a very high energy performance with a low amount of energy required covered to a very significant extent by energy from renewable sources, including energy from renewable sources produced on-site or nearby) (Beglivo et al., 2015)