passive cooling

Buildings account for 40% of EU energy consumption and 36% of the energy related greenhouse gas emissions at present. Consequently, the net zero target set by Energy Performance of Building’s Directive by 2050 for building stock is ambitious to achieve. The often default design choice to adopt mechanical cooling in non-domestic buildings highlights the lack of robust decision support tools or frameworks available to designers to properly evaluate ventilative cooling as a realistic alternative.

The use of the word “resilience” has increased significantly since 2010, however, there is a lack of understanding around 1) how thermal resilience is defined (where some definitions were offered only recently) and 2) what distinguishes it from typical overheating assessments. In addition to this, there is a lack of uptake in the remote monitoring industry (which uses low-cost solutions) when it comes to typical parameters used in thermal comfort studies and there is need to demonstrate how resilience performance can be reported going forward.

Reducing primary energy consumption is an essential issue for the sector of building construction. This paper refers to building ventilation systems and focuses on low pressure flat plate heat exchangers, designed for low pressure drops and low air velocity, minimizing the electrical consumption of fans. The device is conceived for working within passive ventilation systems, as a ventilation heat recovery stage during winter and sensible heat dissipation during summer.

This study analyses the climate-dependent passive ventilative cooling (PVC) potential in central and southern Europe. This analysis was carried out in two phases: (1) evaluation of PVC potential as a climate-dependent variable, in different locations representative of European climate zones for both wind-drive airflow (comfort ventilation) and temperature gradient (environmental and structural cooling); (2) verification of the above PVC potential through dynamic energy simulations on a reference-building model located in selected cities.

The present study aims at assessing the geo-climatic potential applicability of controlled natural ventilation (CNV) as a natural ventilative cooling (NVC) technique in the Mediterranean area. This assessment was carried following two approaches: (1) a climate-dependent evaluation of the NVC potential of different locations considering a “virtual space”; (2) a calculation of the NVC potential of different locations considering a “real” building through dynamic energy simulations.

Different simplified simulation models of a Passive Downdraught Evaporative Cooling tower (PDEC) were compared by using experimental data. Among these, a series of tests on a Passive Downdraught Evaporative Cooling tower (PDEC) were carried out at the SyTIn (Systems for Technology Innovation) Laboratory of the Department of Architecture and Design, Politecnico di Torino. In addition, other monitored databases were taken from literature and used as input data for the simplified models.

The paper aims to evaluate the geo-climatic applicability of two different passive cooling strategies: the passive evaporative cooling (PEC) and the natural ventilative cooling (NVC) in China. The two cooling techniques are analysed following a climate-related approach considering a ‘virtual Space’. NVC potential is assessed by analysing the typical meteorological year related to a set of 105 locations representing different typical Chinese climate conditions. A parametric approach is used in order to virtualise the geo-climatic potential of this cooling technique.

Ventilative cooling through window airing presents a promising potential for low energy houses in order to avoid overheating risks and to reduce energy consumption of air conditioners. This case study aims at describing how ventilative cooling has been taken into account as from the design stage of a low-energy single-family active house located near Paris. Its performance on thermal comfort and air renewal, monitored from both sociological (feedback from a family) and scientific approach, is described and compares these two qualitative and quantitative approaches.

Major and deep energy renovations of single-family houses (more than 60% of the building stock) are expected in Europe over the next several years (Psomas et al., 2016a). A number of research projects have documented and verified overheating risk during the design and operation phase in nearly zero energy or existing renovated single-family houses without mechanical cooling systems in temperate climates. Post occupancy surveys and comfort studies have also monitored high indoor temperatures over 27oC and 28oC even in Northern countries (Psomas et al., 2016a).

The lack of indicators assessing ventilative cooling effectiveness in a way to compare it with active cooling technics, makes its acceptance more difficult. Practitioners, norms, standards and guidelines are used to design and evaluate cooling systems in terms of Cooling Power (CP) or Seasonal Energy Efficiency Ratio (SEER). What could be the CP of a passive technique based on a day to night offset of the cooling process? What could be the SEER of mechanical night ventilation for summer cooling?