**Belen Moreno Santamaria 1, Fernando del Ama Gonzalo 2,\*, Danielle Pinette 2, Benito Lauret Aguirregabiria <sup>1</sup> and Juan A. Hernandez Ramos <sup>3</sup>**


Received: 9 August 2020; Accepted: 11 September 2020; Published: 14 September 2020

**Abstract:** New light envelopes for buildings need a holistic vision based on the integration of architectural design, building simulation, energy management, and the curtain wall industry. Water flow glazing (WFG)-unitized facades work as transparent and translucent facades with new features, such as heat absorption and renewable energy production. The main objective of this paper was to assess the performance of a new WFG-unitized facade as a high-performance envelope with dynamic thermal properties. Outdoor temperature, variable mass flow rate, and solar radiation were considered as transient boundary conditions at the simulation stage. The thermal performance of different WFGs was carried out using simulation tools and real data. The test facility included temperature sensors and pyranometers to validate simulation results. The dynamic thermal transmittance ranged from 1 W/m2K when the mass flow rate is stopped to 0.06 W/m2K when the mass flow rate is above 2 L/min m2. Selecting the right glazing in each orientation had an impact on energy savings, renewable energy production, and CO2 emissions. Energy savings ranged from 5.43 to 6.46 KWh/m2 day in non-renewable energy consumption, whereas the renewable primary energy production ranged from 3 to 3.42 KWh/m<sup>2</sup> day. The CO2 emissions were reduced at a rate of 1 Kg/m<sup>2</sup> day. The disadvantages of WFG are the high up-front cost and more demanding assembly process.

**Keywords:** building energy management; water flow glazing; unitized facade
