Assessing energy savings in cooling demand of buildings using passive cooling systems based on ventilation

Abstract

The objective of this article is to develop and test a simplified method to compute the savings in building cooling demand by use of passive cooling systems based on ventilation (direct night ventilation, air-soil heat exchangers, controlled thermal phaseshifting, evaporative cooling, as well as possible combinations thereof). The systems are characterized in terms of a climatic cooling potential, independently of any building, which is then compared to the cooling load of a particular building. The method is tested against an extensive numerical simulation campaign, combining diverse passive cooling systems and sizes with diverse constructive and operational modes for an administrative building situated in Geneva. The key point of the simplified method is to choose an appropriate time resolution, for taking into account the building thermal inertia. Although best results are obtained with a daily resolution, good results are also obtained with monthly data, where an overestimation of the passive cooling fraction remains less than 20% in half of the cases. This opens way for using the method for first assessing the potential of these passive cooling techniques on a large spatiotemporal scale, for which integrated building and system simulation becomes prohibitive.

Climatic cooling potential and building cooling demand savings: High resolution spatiotemporal analysis of direct ventilation and evaporative cooling for the Iberian Peninsula

“…The method used in the present study closely follows Campaniço et al [24], however, here we characterize any given passive cooling system based on ventilation in terms of its climatic cooling potential CCP in such a way that allows for the assessment of the cooling demand savings provided by it use for any building for any spatiotemporal scale, which was not established in Campaniço et al [24]. In the referred study, CCP was determined in order to allow to compute the cooling demand savings by the use of different passive cooling systems based on ventilation for a specific case/building, here, this climatic index is redefined in such a way that it permits to access the cooling demand savings by the use of different passive 7 cooling systems based on ventilation but for a large spatiotemporal scale and for any building.…”

“…For this sake, the simplified method presented by Campaniço et al [24] was tested against an extensive numerical simulation campaign [24], concerning: (i) the case of an administrative building located in Geneva, with a variety of constructive and operational configurations (solar protection, thermal mass and insulation, internal gains); (ii) an important set of passive cooling techniques (direct ventilation, evaporative cooling, air-soil heat exchangers, thermal phase-shifting, as well as combination thereof) with diverse sizing and flow rates.…”

“…Recently, Campaniço et al [24] were the first to compute a climatic cooling potential for passive cooling systems in a way that it can be directly related to cooling demand savings independent of any building characteristic and without the use of building thermal simulation. In this study, CCP was computed for complete diurnal cycles and then compared to data for building cooling demand, to achieve the cooling demand savings through a simple model.…”

Impact of Climate Change: Environmental Assessment of Passive Solutions in a Single-Family Home in Southern Spain

“…This night-time ventilation should be combined with the heat accumulation processes in the thermal mass [23]. Campaniço et al [46] studied and compared the cooling potential of four passive ventilation-based methods, including direct ventilation, Earth-Air Heat Exchanger (EAHE), controlled thermal phase-shifting and evaporative cooling, and reported that the use of above systems can provide up to 38% cooling demand saving. However, when outdoor conditions drop to the comfort levels during cooling periods, an increase in ventilation rates is beneficial [47].…”

Thermal Storage Systems Assessment for Energy Sustainability in Housing Units

“…The arrangement of heat tubes influences the efficiency of sustainable thermal systems [20]. Several simplified methods have been developed and tested to calculate the savings on cooling necessities using passive cooling systems based on ventilation, among them wind towers, night direct ventilation and air-soil heat exchangers [21]. To assess the efficiency and accuracy of the air flow on buildings, several numerical simulations have been performed [22][23][24].…”