High energy demand associated to the massive use of air conditioning systems requires careful con... more High energy demand associated to the massive use of air conditioning systems requires careful consideration of passive cooling strategies, with evaporative cooling being recognized as a useful possibility for that purpose. One important factor that influences the performance of evaporative cooling systems is the media material that supports water evaporation process. In this work evaporative cooling capabilities of different building
... membros da União. No caso de Portugal, aguarda-se para breve a sua adopção, integrada na impl... more ... membros da União. No caso de Portugal, aguarda-se para breve a sua adopção, integrada na implementação de um Sistema Nacional de Certificação Energética e da Qualidade do Ar Interior nos Edifícios. Aguarda-se, também ...
Sustainable Energy Technologies and Assessments, 2013
The use of passive cooling techniques has been seen as one of the solutions that can help to redu... more The use of passive cooling techniques has been seen as one of the solutions that can help to reduce energy consumption in the building sector. An innovative element that allows the combined use of two passive cooling techniques, evaporative cooling and night ventilation, is proposed in the present work. In order to optimize the use of those techniques it was decided to include in the element configuration a core component with latent heat storage capabilities. Briefly it can be said that the element is composed by the accumulating core, consisting of a cement mortar vertical panel impregnated with paraffin, with two adjacent channels for air circulation. The element, whose configuration should allow its integration into the buildings envelope, has a parallelepiped shape with one air inlet and one air outlet in each of its opposite faces, the exterior and the interior ones. The core surface adjacent to the exterior channel is maintained continuously wetted by a water sprinkler system integrated in the element. The airflow in each channel is provided by tangential fans mounted on top of the element. The paraffin wax used corresponds to a commercial wax with phase transition range near 21°C, slightly below typical comfort temperatures. A prototype of the element was constructed and subjected to a series of experimental studies that aim to know its response in operating conditions similar to real ones. These studies took place in a climate chamber for a wide range of conditions. The results suggest that the proposed element exhibits the potential for passive cooling of buildings. It was concluded that the paraffin wax incorporation in the cement mortar core has substantially improved the capacity of thermal energy accumulation of the element, that the evaporation process on the outside surface of the core provides a substantial temperature reducing of the core, and that its use also during night-time periods allows to cool the core well below the outside temperatures, thus maximizing the possibility of application of night ventilation.
Resumo Nos anos mais recentes tem-se assistido em simultâneo ao crescimento mundial do consumo de... more Resumo Nos anos mais recentes tem-se assistido em simultâneo ao crescimento mundial do consumo de energia primária e ao aumento generalizado do preço dos combustíveis. Acresce ainda que quer Portugal quer a União Europeia apresentam uma grande dependência energética em relação a países terceiros. Quando a análise de consumos é feita por sectores verifica-se que o consumo correspondente aos edifícios é significativamente elevado. Ultimamente este consumo tem também vindo a crescer, em particular o relativo ao arrefecimento. Torna-se, assim, importante adoptar medidas que de um modo geral permitam reduzir o consumo de energia e que em particular sejam efectivas no caso dos edifícios. Neste artigo apresentam-se resultados experimentais preliminares relativos ao comportamento de um elemento a ser integrado na envolvente dos edifícios e cujo objectivo é precisamente participar no seu arrefecimento interior com reduzidos custos energéticos. O elemento passivo desenvolvido utiliza de forma combinada a ventilação nocturna, a acumulação de frio e o arrefecimento evaporativo. Desta forma permite adequar as potencialidades de cada uma das técnicas às necessidades de arrefecimento do edifício colmatando as limitações que resultariam da sua aplicação isolada. Inicialmente foi construído um modelo à escala experimental desse elemento da envolvente que, depois de convenientemente instrumentado, foi submetido a diferentes condições de operação numa câmara climática. O elemento possui um núcleo em argamassa impregnada com uma substância acumuladora e cuja temperatura de transição de fase se adequa ao fim pretendido. A superfície do elemento em contacto com o ar exterior foi revestida por um material poroso que quando molhado permite a ocorrência de arrefecimento evaporativo indirecto. Os resultados preliminares indicam que este tipo de elemento pode ser utilizado com sucesso no arrefecimento passivo de edifícios.
The use of passive cooling techniques has been seen as one of the solutions that can help to redu... more The use of passive cooling techniques has been seen as one of the solutions that can help to reduce energy consumption in the building sector. An innovative element that allows the combined use of two passive cooling techniques, evaporative cooling and night ventilation, is proposed in the present work. In order to optimize the use of those techniques it was decided to include in the element configuration a core component with latent heat storage capabilities. Briefly it can be said that the element is composed by the accumulating core, consisting of a cement mortar vertical panel impregnated with paraffin, with two adjacent channels for air circulation. The element, whose configuration should allow its integration into the buildings envelope, has a parallelepiped shape with one air inlet and one air outlet in each of its opposite faces, the exterior and the interior ones. The core surface adjacent to the exterior channel is maintained continuously wetted by a water sprinkler system integrated in the element. The airflow in each channel is provided by tangential fans mounted on top of the element. The paraffin wax used corresponds to a commercial wax with phase transition range near 21 C, slightly below typical comfort temperatures. A prototype of the element was constructed and subjected to a series of experimental studies that aim to know its response in operating conditions similar to real ones. These studies took place in a climate chamber for a wide range of conditions. The results suggest that the proposed element exhibits the potential for passive cooling of buildings. It was concluded that the paraffin wax incorporation in the cement mortar core has substantially improved the capacity of thermal energy accumulation of the element, that the evaporation process on the outside surface of the core provides a substantial temperature reducing of the core, and that its use also during night-time periods allows to cool the core well below the outside temperatures, thus maximizing the possibility of application of night ventilation.
High energy demand associated to the massive use of air conditioning systems requires careful con... more High energy demand associated to the massive use of air conditioning systems requires careful consideration of passive cooling strategies, with evaporative cooling being recognized as a useful possibility for that purpose. One important factor that influences the performance of evaporative cooling systems is the media material that supports water evaporation process. In this work evaporative cooling capabilities of different building
... membros da União. No caso de Portugal, aguarda-se para breve a sua adopção, integrada na impl... more ... membros da União. No caso de Portugal, aguarda-se para breve a sua adopção, integrada na implementação de um Sistema Nacional de Certificação Energética e da Qualidade do Ar Interior nos Edifícios. Aguarda-se, também ...
Sustainable Energy Technologies and Assessments, 2013
The use of passive cooling techniques has been seen as one of the solutions that can help to redu... more The use of passive cooling techniques has been seen as one of the solutions that can help to reduce energy consumption in the building sector. An innovative element that allows the combined use of two passive cooling techniques, evaporative cooling and night ventilation, is proposed in the present work. In order to optimize the use of those techniques it was decided to include in the element configuration a core component with latent heat storage capabilities. Briefly it can be said that the element is composed by the accumulating core, consisting of a cement mortar vertical panel impregnated with paraffin, with two adjacent channels for air circulation. The element, whose configuration should allow its integration into the buildings envelope, has a parallelepiped shape with one air inlet and one air outlet in each of its opposite faces, the exterior and the interior ones. The core surface adjacent to the exterior channel is maintained continuously wetted by a water sprinkler system integrated in the element. The airflow in each channel is provided by tangential fans mounted on top of the element. The paraffin wax used corresponds to a commercial wax with phase transition range near 21°C, slightly below typical comfort temperatures. A prototype of the element was constructed and subjected to a series of experimental studies that aim to know its response in operating conditions similar to real ones. These studies took place in a climate chamber for a wide range of conditions. The results suggest that the proposed element exhibits the potential for passive cooling of buildings. It was concluded that the paraffin wax incorporation in the cement mortar core has substantially improved the capacity of thermal energy accumulation of the element, that the evaporation process on the outside surface of the core provides a substantial temperature reducing of the core, and that its use also during night-time periods allows to cool the core well below the outside temperatures, thus maximizing the possibility of application of night ventilation.
Resumo Nos anos mais recentes tem-se assistido em simultâneo ao crescimento mundial do consumo de... more Resumo Nos anos mais recentes tem-se assistido em simultâneo ao crescimento mundial do consumo de energia primária e ao aumento generalizado do preço dos combustíveis. Acresce ainda que quer Portugal quer a União Europeia apresentam uma grande dependência energética em relação a países terceiros. Quando a análise de consumos é feita por sectores verifica-se que o consumo correspondente aos edifícios é significativamente elevado. Ultimamente este consumo tem também vindo a crescer, em particular o relativo ao arrefecimento. Torna-se, assim, importante adoptar medidas que de um modo geral permitam reduzir o consumo de energia e que em particular sejam efectivas no caso dos edifícios. Neste artigo apresentam-se resultados experimentais preliminares relativos ao comportamento de um elemento a ser integrado na envolvente dos edifícios e cujo objectivo é precisamente participar no seu arrefecimento interior com reduzidos custos energéticos. O elemento passivo desenvolvido utiliza de forma combinada a ventilação nocturna, a acumulação de frio e o arrefecimento evaporativo. Desta forma permite adequar as potencialidades de cada uma das técnicas às necessidades de arrefecimento do edifício colmatando as limitações que resultariam da sua aplicação isolada. Inicialmente foi construído um modelo à escala experimental desse elemento da envolvente que, depois de convenientemente instrumentado, foi submetido a diferentes condições de operação numa câmara climática. O elemento possui um núcleo em argamassa impregnada com uma substância acumuladora e cuja temperatura de transição de fase se adequa ao fim pretendido. A superfície do elemento em contacto com o ar exterior foi revestida por um material poroso que quando molhado permite a ocorrência de arrefecimento evaporativo indirecto. Os resultados preliminares indicam que este tipo de elemento pode ser utilizado com sucesso no arrefecimento passivo de edifícios.
The use of passive cooling techniques has been seen as one of the solutions that can help to redu... more The use of passive cooling techniques has been seen as one of the solutions that can help to reduce energy consumption in the building sector. An innovative element that allows the combined use of two passive cooling techniques, evaporative cooling and night ventilation, is proposed in the present work. In order to optimize the use of those techniques it was decided to include in the element configuration a core component with latent heat storage capabilities. Briefly it can be said that the element is composed by the accumulating core, consisting of a cement mortar vertical panel impregnated with paraffin, with two adjacent channels for air circulation. The element, whose configuration should allow its integration into the buildings envelope, has a parallelepiped shape with one air inlet and one air outlet in each of its opposite faces, the exterior and the interior ones. The core surface adjacent to the exterior channel is maintained continuously wetted by a water sprinkler system integrated in the element. The airflow in each channel is provided by tangential fans mounted on top of the element. The paraffin wax used corresponds to a commercial wax with phase transition range near 21 C, slightly below typical comfort temperatures. A prototype of the element was constructed and subjected to a series of experimental studies that aim to know its response in operating conditions similar to real ones. These studies took place in a climate chamber for a wide range of conditions. The results suggest that the proposed element exhibits the potential for passive cooling of buildings. It was concluded that the paraffin wax incorporation in the cement mortar core has substantially improved the capacity of thermal energy accumulation of the element, that the evaporation process on the outside surface of the core provides a substantial temperature reducing of the core, and that its use also during night-time periods allows to cool the core well below the outside temperatures, thus maximizing the possibility of application of night ventilation.
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