Abstract
One of the most critical objectives in buildings is their adaptation to environmental conditions in order to optimize energy performance as well as the thermal and visual comfort of the occupants. This issue is relevant, for example, in public buildings that incorporate large glazed surfaces, where overheating and a lack of thermal and visual comfort are common, especially in Mediterranean countries. The headmost cause of increased air conditioning loads is direct solar radiation on transparent surfaces. However, the significant losses through glazed surfaces in cold climates also cannot be ignored. Therefore, solar protections must be used, thus observing the harmful effects of the absence of solar radiation on energy loads in winter. This chapter aims to study and compare construction materials recently introduced to the market, such as dynamic glasses, with significantly higher thermal and optical performance than traditional glasses.
TopIntroduction
Optimizing the energy performance and the thermal and visual comfort are the most important goals for new buildings design. This issue is relevant, for example, in public buildings, generally in those that incorporate large glazed surfaces, because of overheating problems and lack of thermal and visual comfort, especially in Mediterranean latitudes, such as in Spain. As mentioned, the most crucial cause of the increase in air conditioning loads, among others, is direct solar radiation on transparent surfaces. Accordingly, solar shielding elements are recommended, even though the absence of solar radiation can cause adverse effects on energy loads.
The first point that must be addressed in dealing with innovative transparent materials is to establish which ones are considered dynamic or static glasses. On the other hand, there are categories of insulating or low-emissive materials that have already been in the market for years and have significantly higher optical performance than traditional glasses. This consideration makes it necessary to include all the transparent elements whose optical and thermal characteristics differ from single glass or standard double glazing in this chapter. Therefore, the apparent differences found in these new products compared to simple glass or that with an air chamber are due to:
- •
A higher thickness.
- •
Deposition of a thin film (of various natures) on the flat glass.
- •
Filling the double-glazed chamber (with insulating materials, vacuum, or low emissive inert gases).
In the background section of this chapter, the double-skin facades will first be studied, then moving on to the study of glass, distinguishing between them in static and dynamic, focusing on Water Flow Glazing facades. Next, different solutions, including glass types and energy systems, will be tested through theoretical models to study the dynamic Water Flow Glazing's capabilities to improve their environments' energy saving and comfort. Finally, an economic analysis will show the Return of Investment (ROI) of different scenarios to explain the balance between cost and efficiency.
TopBackground
The Energy Performance Buildings Directive (EPBD) encourages procedures and materials to design energy-efficient and decarbonized facilities by 2050 (European Union, 2018). Zero-energy buildings generate as much energy from renewable technologies as their energy consumption (Sudhakar et al, 2019). Therefore, developing passive strategies is the first step to accomplishing Net Zero Energy goals. Further action comprises the integration of technologies for energy production and management (Frattolillo et al, 2020). It is a fundamental aspect of this chapter to differentiate between static glasses, those that do not change their properties over time and dynamic ones, those that are able to modify them, either by the external climatic conditions or by the user (Casini, 2015).
Key Terms in this Chapter
Dynamic U-Value: A measure of heat loss in an element of the building envelope depending on the variable mass flow rate through the water flow glazing. It is indicated in units of Watts per meter squared per Kelvin W/(m 2 K).
Water Flow Glazing: A double or triple glazing with a water chamber connected to a circulating device allowing the flow of water through the glass panel in a closed-circuit exchanging heat with the environment.
Building Envelope: The integrated elements of a building that separate its interior from the outdoor environment.
Circulating System: A group of devices that allows the water flow through the Water Flow Glazing and it is made of at least a water pump, a heat plate exchanger, and a precision flow meter and a thermometer for monitoring the inlet and outlet temperature.
Mass Flow Rate: The mass of a fluid which passes through the water flow glazing cavity per unit of time. It is indicated in units of kilogram per second.
Dynamic G-Factor: The coefficient used to measure the glazing’s ability to transmit solar energy can change in response to an environmental, temperature, or electrical control. Water Flow Glazing can vary its dynamic g-factor by changing the mass flow rate.