Possible benefits of capillary flow glazing in translucent wall elements

Nestle, Nikolaus; Pulbere, Sorin; Alston, Mark

Abstract

In many cases, artificial lighting and cooling are the two main factors for energy consumption in office buildings. This is even true for fully glazed buildings where directly transmitted natural light often needs to be controlled by shading in order to avoid glare problems and an unfavorable distribution of light within the room. Furthermore, transmitted solar irradiation leads to additional solar gains which in turn increase the cooling load of buildings. Replacing transparent elements in the facade by translucent elements where no visual contact with the exterior is needed, will lead to considerable improvements with respect to better light distribution over the depth of the room and to reduction of glare problems. However, issues with solar gains remain essentially the same. As visible light makes up only half of the incident solar irradiation, solar gains associated with incoming daylight could be seriously reduced by filtering out the invisible irradiation which predominantly is in the so-called near IR (NIR) range of the electromagnetic spectrum. In principle, filtering out this part of the solar irradiation spectrum can be achieved by selective reflection or by selective absorption. Due to the physics of the underlying effects, spectrally selective reflection of NIR is more challenging than absorption. However, absorption will lead to heating of the absorber. Especially in translucent elements with good thermal insulation, heating will lead to a lot of unwanted issues with thermal stresses induced into the absorber material. Like that, reducing the heat load in the absorber layer is desirable and might even come with the additional benefit of using the absorber layer as a translucent solar thermal collector. In this contribution, we present the use of capillary flow glazing as a possible solution to this problem. A bio-inspired engineering approach for a channel system with optimized hydrodynamics is presented. Furthermore, we will discuss the optimal position of the capillary layer in static and adaptive translucent glazing elements for different climate conditions and possible approaches to use the heat collected by the capillary system within a holistic energy management concept for a building.

Citation

Nestle, N., Pulbere, S., & Alston, M. (2018). Possible benefits of capillary flow glazing in translucent wall elements. In N/a

• Conference Name: FAÇADE 2018 Final conference of COST TU1403 “Adaptive Facades Network”
• Start Date: Nov 26, 2018
• End Date: Nov 27, 2018
• Acceptance Date: Sep 13, 2018
• Online Publication Date: Nov 26, 2018
• Publication Date: Nov 26, 2018
• Deposit Date: Oct 31, 2018
• Publicly Available Date: Oct 31, 2018
• Journal: FAÇADE 2018 Final conference of COST TU1403
• Book Title: N/a
• Chapter Number: N/a
• ISBN: N/a
• Keywords: Adaptive building envelope; solar radiation management; capillary; hydrodynamics; heat management
• Public URL: https://nottingham-repository.worktribe.com/output/1212783