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- Air flow exchange velocity of urban canyon cavities due to thermal spatial differencesPublication . Panão, Marta Oliveira; Goncalves, Helder; Ferrão, PauloIn this paper, the air exchange velocity between the urban canyon cavity and the air layer above roof level is quantified, using a two-dimensional k-ε model, and correlated with the air cavity mean temperature, for two cases: leeward and downward wall heating. The spatial thermal differences are evaluated by assuming a wall temperature higher than the air temperature, with this difference ranging between 0 and 16 K. The undisturbed wind velocity above the roof level is varied from 1 to 6 ms-1 and the canyon aspect ratio is 1.5, which corresponds to a skimming flow regime. The model predicts two situations, which correspond to air flow regimes where one or two eddies are formed, respectively: (a) for high wind speed, the air inside the cavity is negligible affect by the buoyancy effect and the air exchange velocity linearly increases with the increase of wind velocity; (b) for low wind speed, when the buoyancy forces are stronger than the wind induced forces, the air exchange velocity is not a linear function with the wind velocity. The transition wind velocity between (a) and (b) is a function of the wall-air temperature difference. The situation of windward heated wall and two eddies air flow regime is the most favorable to extract heat from the cavity. On the contrary, the heated air is hardly extracted from the cavity when only the wind induced eddy is predicted and windward wall is heated. In this situation an increase of 10 K on the wall temperature increases by 1 K the in-cavity air temperature.
- Analysis matrix : passive approachesPublication . Aelenei, Laura Elena; Goncalves, Helder
- Applications of PCMsPublication . Solé, Cristian; Kalagirou, Soteris; Navarro, Lidia; Gracia, Alvaro de; McCormack, Sarah; Hasan, Ahmad; Aelenei, Laura Elena; Ostry, Milan; Georgiev, Aleksandar; Popov, Rumen; Bottarelli, Michele; Griffiths, Philip; O'Brien, VicentThis section will consider a number of applications of phase change materials. The work was compiled as part of the applications working group of TU0802. This chapter is a précis of the work which can be read in detail in the deliverables published by the COST action.
- Assessement of the Portuguese building thermal code: Newly revised requirements for cooling energy needs used to prevent the overheating of buildings in the summerPublication . Panão, Marta Oliveira; Camelo, Susana; Goncalves, HelderIn this paper, cooling energy needs are calculated by the steady-state methodology of the Portuguese building thermal code. After the first period of building code implementation, re-evaluation according to EN ISO 13790 is recommended in order to compare results with the dynamic simulation results. From these analyses, a newly revised methodology arises including a few corrections in procedure. This iterative result is sufficiently accurate to calculate the building’s cooling energy needs. Secondly, results show that the required conditions are insufficient to prevent overheating. The use of the gain utilization factor as an overheating risk index is suggested, according to an adaptive comfort protocol, and is integrated in the method used to calculate the maximum value for cooling energy needs. This proposed streamlined method depends on reference values: window-to-floor area ratio, window shading g-value, integrated solar radiation and gain utilization factor, which leads to threshold values significantly below the ones currently used. These revised requirements are more restrictive and, therefore, will act to improve a building’s thermal performance during summer. As a rule of thumb applied for Portuguese climates, the reference gain utilization factor should assume a minimum value of 0.8 for a latitude angle range of 40-41ºN, 0.6 for 38-39ºN and 0.5 for 37ºN.
- Balanço energético nulo dos edifícios: é fazível?Publication . Aelenei, Laura Elena
- BIPV/T versus BIPV/T-PCM: A numerical investigation of advanced system integrated into Solar XXI building façadePublication . Aelenei, Laura Elena; Pereira, R.; Goncalves, Helder
- Buildings of the futurePublication . Aelenei, Laura Elena
- Case studies : adaptive facade networkPublication . Aelenei, Laura Elena; Aelenei, Daniel; Romano, Rosa; Mazzucchelli, Enrico Sergio; Brzezicki, Marcin; Rico-Martinez, Jose MiguelABSTRACT: Adaptive building envelopes can provide improvements in building energy efficiency and economics, through their capability to change their behaviour in real time according to indooroutdoor parameters. This may be by means of materials, components or systems. As such, adaptive façades can make a significant and viable contribution to meeting the EU´s 2020 targets. Several different adaptive façade concepts have already been developed, and an increase in emerging, innovative solutions is expected in the near future. In this context the EU initiative COST Action TU 1403 aims to harmonize, share and disseminate technological knowledge on adaptive facades at a European level. According to the definition given by this COST Action, an adaptive façade is a building envelope consisting of multifunctional and highly adaptive systems that is able to change its functions, features, or behaviour over time in response to transient performance requirements and boundary conditions, with the aim of improving the overall building performance. In order to explore the available and emerging technologies focusing on adaptive façades, Working Group 1 of the COST Action undertook research to form a database of adaptive façade case studies and projects structured in accordance with a simple classification – materials, components and systems. In addition to this, details of the purpose of the systems/components/materials with adaptive features and the working principle of each technology were also collected together with data regarding design practice, technology readiness, and economical aspects, among others. The information was collected with the help of a specific online survey (structured in the following main sections: detailed description - metrics- characterization- economic aspects – references). The database includes 165 cases of adaptive façade systems, components, and materials that allowed a variety of analyses to be carried out. According to the classification adopted within WG1 (materials, components, systems), each of the classification terms are introduced together with examples from the case study database in the following sections. This volume ends with a section dedicated to future developments, where different issues are addressed such as embedded functionality and efficiency amd biomimetic inspirations. The importance of adaptive façades through their flexibility, and intelligent design within the context of smart cities is also discussed.
- Climatologia e anos meteorológicos de referência para o Sistema Nacional de Certificação de Edifícios (versão 2013)Publication . Aguiar, Ricardo; Carvalho, Maria João; Goncalves, Helder
- Comportamento térmico de edifícios solares passivos - ficha 3.8Publication . Goncalves, Helder; Camelo, Susana