Experimental study of an innovative element for passive cooling of buildings

Abstract 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.

[1]  Onorio Saro,et al.  Numerical analysis of heat and mass transfer in a passive building component cooled by water evaporation , 2002 .

[2]  Umberto Desideri,et al.  Solar-powered cooling systems: Technical and economic analysis on industrial refrigeration and air-conditioning applications , 2009 .

[3]  Rakesh Kumar,et al.  Assessment of permeation quality of concrete through mercury intrusion porosimetry , 2004 .

[4]  Wei Chen,et al.  Thermal analysis on the cooling performance of a porous evaporative plate for building , 2010 .

[5]  Ursula Eicker,et al.  Cooling strategies, summer comfort and energy performance of a rehabilitated passive standard office building , 2010 .

[6]  K. Nagano,et al.  Experimental study of the performance of porous materials to moderate the roof surface temperature by its evaporative cooling effect , 2009 .

[8]  Mario A. Medina,et al.  Development of a thermally enhanced frame wall with phase‐change materials for on‐peak air conditioning demand reduction and energy savings in residential buildings , 2005 .

[9]  Fu-Sheng Gao,et al.  Night ventilation control strategies in office buildings , 2009 .

[10]  Nebojsa Nakicenovic,et al.  Lighting the Way: Toward a Sustainable Energy Future , 2007 .

[11]  Guk-Rwang Won.  American Society for Testing and Materials , 1987 .

[12]  Lina Yang,et al.  Cooling load reduction by using thermal mass and night ventilation , 2008 .

[13]  L. Pires,et al.  Transient behaviour of a latent-heat thermal-energy store: numerical and experimental studies , 2002 .

[14]  K. Pavlou,et al.  Recent progress on passive cooling techniques: Advanced technological developments to improve survivability levels in low-income households , 2007 .

[15]  Beat Lehmann,et al.  Development of a thermally activated ceiling panel with PCM for application in lightweight and retrofitted buildings , 2004 .

[16]  Rasmus Lund Jensen,et al.  Experimental investigation of heat transfer during night-time ventilation , 2010 .

[17]  Bernard Souyri,et al.  Night cooling with a Ventilated Internal Double Wall , 2010 .

[18]  M. Sivak.  Potential energy demand for cooling in the 50 largest metropolitan areas of the world: Implications for developing countries , 2009 .