Browsing by Keyword "Building envelopes"
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Item Data driven process for the energy assessment of building envelope retrofits(2020-06-30) Garay-Martinez, Roberto; Arregi, Beñat; Lumbreras, Mikel; Zurro, Belén; Gonzalez, Jose Manuel; Hernandez, Jose Luis; Tecnalia Research & Innovation; EDIFICACIÓN DE ENERGÍA POSITIVAIn the last decades, a growing industry has been created in relation to building envelope retrofits. Linked to the lack of financial capacity of many building owners, innovative instruments such as energy performance contracts have been promoted by public bodies. This kind of instruments require of detailed energy assessment processes in order to define the expected heat load reduction and the associated economic flows between building owners and Energy Services Companies. When dealing with building envelopes, existing methods for building envelope heat loss characterization require of substantial efforts in terms of equipment and time, which makes them difficult to apply in real practice. In this paper, a novel method is proposed based on whole-building heat load assessment by means of heat meters, and analytical calculations of building envelope transmission heat load coefficients. This method, which requires minimal or no additional equipment, can be used over historical data from District Heating systems. It assigns a specific load fraction to building envelope heat transfer and allows to assess the expected reduction due to the building envelope retrofit. Numerical and experimental data is presented based on an educational building in the city of Burgos, Spain.Item Hybrid numerical and experimental performance assessment of structural thermal bridge retrofits(2018) Garay, Roberto; Garay Martinez, Roberto; Tecnalia Research & InnovationA methodological approach to the multi-dimensional heat transfer assessment of building envelopes is performed. The proposed method is particularly focused on thermally weak points in envelope-structure junctions and the assessment of envelope retrofit alternatives. Thermal performance in these spots is seldom assessed in energy audit processes, although it is one of the main heat loss paths in many insulated façade solutions. An envelope-slab junction case is presented, where multi-dimensional heat transfer occurs. The present paper proposes a methodology which allows for a hybrid experimental and numerical performance assessment in such circumstances. A numerical model is calibrated against experimental data, which is then modified to reflect various envelope retrofit solutions. Several possible analysis procedures are proposed, based on the capacities of transient thermal models.Item Monitoring and thermal performance evaluation of two building envelope solutions in an apartment building(2020-06-30) Arregi, Beñat; Garay-Martinez, Roberto; Astudillo, Julen; Ramos, Juan Carlos; Tecnalia Research & Innovation; EDIFICACIÓN DE ENERGÍA POSITIVAA bio-based multi-layer building envelope assembly has been developed for its integration in newly built and retrofitted buildings. Forest-based materials and biocomposite profiles are used as an alternative to fossil-based insulants and metallic framing, providing a well-insulated and low-thermal-bridge technical solution. The wall assembly has been installed as the external envelope of one apartment of a housing block in Donostia-San Sebastián (Basque Country, Spain). A comparative study has been performed for the bio-based wall and the reference wall of the building. Their in-situ thermal resistance has been obtained by means of three different methods: (1) the steady-state average method, (2) a semi-dynamic method from heat balance at the internal surface, and (3) a dynamic multiple regression method. Reasonably consistent results have been obtained with the three methods: a discussion is provided on the influence of measuring periods and boundary conditions. Outputs from this experimental campaign are valuable as a counterpoint to desktop studies and tests under controlled laboratory conditions. Learnings and outputs from the present study should contribute to a better understanding of the in-situ performance of building envelope assemblies and their assessment methods.Item Performance assessment of an unglazed solar thermal collector for envelope retrofitting(2017-06) Martinez, Roberto Garay; Goikolea, Beñat Arregi; Paya, Ignacio Gomis; Bonnamy, Paul; Raji, Saed; Lopez, Jerôme; Tecnalia Research & Innovation; EDIFICACIÓN DE ENERGÍA POSITIVAPresent trends on solar thermal systems for building integration define the need of integrated solar technologies for façades. Although other possibilities exist for solar thermal systems in new buildings, solutions for a suitable integration of solar thermal systems into building retrofitting actuations are needed. This paper presents a solar thermal collector system which hybridizes already existing ventilated façade cladding systems into a low temperature solar thermal collector. Numerical and experimental data is presented.Item Performance assessment of façade integrated glazed air solar thermal collectors(2017) Martinez, Roberto Garay; Larraz, Julen Astudillo; Tecnalia Research & Innovation; ECOEFICIENCIA DE PRODUCTOS DE CONSTRUCCIÓNPresent trends on solar thermal systems for building integration define the need of integrated solar technologies for façades. The integration of solar systems in façades allows for the direct connection of solar systems to heated spaces, and automated air solar collectors based on the trombe-mitchell provide a suitable technology for its adoption in multi-rise buildings with decentralized-individual HVAC systems in Central-European and Mediterranean heating dominated climates. This paper reviews the main principles of such building envelope components, and the construction and design considerations of two air-based solar thermal collectors. Full scale preliminary prototypes of these systems were tested at the KUBIK by Tecnalia test facility in an Oceanic Climate (Koppen Geiger Cfb zone). The observed thermal performance is analyzed, and the process of a full scale installation in a real building envelope retrofitting process of a building in Spain is reviewed.Item Simulation of unglazed solar thermal systems integrated into façade & combined with ultra-low temperature district heating(International Building Performance Simulation Association, 2019) Lumbreras, Mikel; Garay, Roberto; Corrado, Vincenzo; Fabrizio, Enrico; Gasparella, Andrea; Patuzzi, Francesco; Tecnalia Research & InnovationThis paper presents a theoretical simulation of thermal and economical assessment of façade integrated Solar Thermal (ST) in combination with Ultra Low Temperature (ULT) District-Heating (DH). This paper is in line with existing R&D activities for the integration of unglazed systems in building envelopes, where facades provide an almost unexplored area for increasing solaractivated building envelopes. The combination of building-integrated solar systems with DH networks avoids the use of local storage and allows a novel combination of heat directionality, both from building to the heat grid and vice versa. A control algorithm for heat supply is presented, so that the performance of the overall system is the optimal. Energetic results from solar simulations and economic assessment derived from the balance of building energy demand and solar production are presented. Over a fullyear period the proposed unglazed system produces as much as 50% additional heat when compared with an isolated ST system and profitable economic metrics are reached over a simulation time of 20 years. Finally, it is concluded the heat sink nature of a DH network, for as many as 25-35% of the buildings connected to the DH includes ST system.