Contribution of Water Flow Glazing to Net-Zero Energy Buildings: Validation of Analytical and Numerical Models Through Experimental Data

Introduction

The Energy Performance Buildings Directive (EPBD) promotes policies that will produce highly energy-efficient and decarbonized structures by 2050. Starting December 31st of 2020, all new buildings will have to be Nearly Zero Energy Buildings. According to this directive, Zero Energy Buildings are defined as those that have a very low energy yearly energy consumption, which can be achieved by both highest energy efficiency and by energy from renewable sources, which shall be on-site or nearby (European Union, 2018). These balance concepts are hardly comparable, do not typically represent national standards, and differ for several reasons. The word “Net” suggests that the mission of the Zero Energy Building is to produce a balance between energy needs and energy consumption, as well as the production of energy and exportation of this energy to the greater power grid. The goal of Net-Zero Energy Buildings (NetZEB) is quite simple: to produce a neutral result for energy or emission balance, which should be created within the time span of one year. This goal can usually be achieved in buildings by implementing a two-step concept: reducing energy demand (via implementing passive means), as well as producing energy on-site (through photo-voltaic panels, wind turbines or Solar Thermal Collectors).

Several different variables must be taken into consideration when accounting for NetZEB energy. These variables could include but are not limited to heating, ventilation, and air-conditioning (HVAC) systems, domestic hot water (DHW), lighting (both indoor and outdoor), plug loads, and transportation within the building itself. Several factors have to be taken into account to set a global standard to define a NetZEB. Firstly, the choice of key performance indicators (i.e., final energy, primary energy, equivalent carbon emissions, and energy costs). Secondly, the “accounting system” used to classify the energy demands into sectors that are included in the balance (i.e., HVAC systems, domestic hot water, and lighting). Finally, we must look at “conversion factors” regarding the chosen metric (political factors, asymmetric weighting factors, and time-dependent conversion factors). The project “Industrial Development of Water Flow Glazing Systems” InDeWaG, supported by program Horizon 2020-EU.3.3.1, was committed to reducing energy consumption and carbon footprint by smart and sustainable use of the building envelope. The research (and furthermore, the project as a whole) assumed that achieving the goals of greater efficiency, aesthetic quality, and commercial renovation could only be accomplished by introducing a broad set of technologies that would encompass all of the various requirements of a building: energy, structure, and function. One of the goals of InDeWaG was to provide the building industry with a new unitized façade typology that, when coupled with a plug and play piping system, would produce a high-performance building envelope and innovative heating and cooling system.

The first goal of this chapter is to validate water flow glazing technology using real data gathered from the prototypes built within the European Project “Industrial Development of Water Flow Glazing Systems” (InDeWaG). The second goal is to develop key performance indicators to assess the performance of water flow glazing and its potential to be used in NetZEB design. The text defines some architectural issues for using Water Flow Glazing in NetZEBs design, which implies re-think the way buildings are designed.