Analysis of resilience of ventilative cooling technologies in a case study building

Buildings globally are subjected to climate change and heatwaves, causing a risk of overheating and increasing energy use for cooling. Low- energy cooling solutions such as night cooling are promising to realize energy reduction and climate goals. Apart from energy performances, resilience is gaining importance in assessing the performance of the building and its systems. Resilience is defined as “an ability to withstand disruptions caused by extreme weather events, man-made disasters, power failure, change in use and atypical conditions; and to maintain capacity to adapt, learn and transform.” However, there is a clear lack of Resilience indicators specific for low energy cooling technologies. In this paper, the resilience of the night cooling in a residential building in Belgium is assessed for two external events: heat wave and shading failure. This paper shows the first attempt of a resilience indicator for night cooling as the effect on the shock of solar shading failure, heat wave or combination of both. It take 3.4 days to bring down the temperature below 25?, in case of shading failure and heatwaves compared to 9 hours in the reference case. Further research is needed to determine resilience indicators as a performance criteria of low-energy cooling systems

Typical and extreme weather datasets for studying the resilience of buildings to climate change and heatwaves

peer reviewedWe present unprecedented datasets of current and future projected weather files for building simulations in 15 major cities distributed across ten climate zones worldwide. The datasets include ambient air temperature, relative humidity, atmospheric pressure, direct and diffuse solar irradiance, and wind speed at hourly resolution, which are essential climate elements needed to undertake building simulations. The datasets contain typical and extreme weather years in the EnergyPlus weather file (EPW) format and multiyear projections in comma-separated value (CSV) format for three periods: historical (2001-2020), future mid-term (2041-2060), and future long-term (2081-2100). The datasets were generated from projections of one regional climate model, which were bias-corrected using multiyear observational data for each city. The methodology used makes the datasets among the first to incorporate complex changes in the future climate for the frequency, duration, and magnitude of extreme temperatures. These datasets, created within the IEA EBC Annex 80 “Resilient Cooling for Buildings”, are ready to be used for different types of building adaptation and resilience studies to climate change and heatwaves.11. Sustainable cities and communitie

Resilient cooling strategies – A critical review and qualitative assessment

The global effects of climate change will increase the frequency and intensity of extreme events such as heatwaves and power outages, which have consequences for buildings and their cooling systems. Buildings and their cooling systems should be designed and operated to be resilient under such events to protect occupants from potentially dangerous indoor thermal conditions. This study performed a critical review on the state-of-the-art of cooling strategies, with special attention to their performance under heatwaves and power outages. We proposed a definition of resilient cooling and described four criteria for resilience—absorptive capacity, adaptive capacity, restorative capacity, and recovery speed —and used them to qualitatively evaluate the resilience of each strategy. The literature review and qualitative analyses show that to attain resilient cooling, the four resilience criteria should be considered in the design phase of a building or during the planning of retrofits. The building and relevant cooling system characteristics should be considered simultaneously to withstand extreme events. A combination of strategies with different resilience capacities, such as a passive envelope strategy coupled with a low-energy space-cooling solution, may be needed to obtain resilient cooling. Finally, a further direction for a quantitative assessment approach has been pointed out

Analysis of resilience of ventilative cooling technologies in a case study building

Buildings globally are subjected to climate change and heatwaves, causing a risk of overheating and increasing energy use for cooling. Low- energy cooling solutions such as night cooling are promising to realize energy reduction and climate goals. Apart from energy performances, resilience is gaining importance in assessing the performance of the building and its systems. Resilience is defined as “an ability to withstand disruptions caused by extreme weather events, man-made disasters, power failure, change in use and atypical conditions; and to maintain capacity to adapt, learn and transform.” However, there is a clear lack of Resilience indicators specific for low energy cooling technologies. In this paper, the resilience of the night cooling in a residential building in Belgium is assessed for two external events: heat wave and shading failure. This paper shows the first attempt of a resilience indicator for night cooling as the effect on the shock of solar shading failure, heat wave or combination of both. It takes 3.4 days to bring down the temperature below 25℃, in case of shading failure and heatwaves compared to 9 hours in the reference case. Further research is needed to determine resilience indicators as a performance criteria of low-energy cooling systems.status: Published onlin

Development of an Assessment Methodology for Resilient Cooling

status: accepte

Evaluation of the spatial aspect of building resilience in classrooms equipped with displacement ventilation

Throughout their lifetime, buildings might face unpredictable shocks leading to fast deterioration of comfort levels. The ability of buildings and systems to absorb the shock and bring back the indoor conditions to their designed state is termed as “resilience”. Ventilation and thermal resilience have been studied under homogeneous conditions. However, the established airflow indoors and hence resilience is non-homogeneous. In this work, the spatial aspect of ventilation and thermal resilience will be assessed in a classroom equipped with displacement ventilation using 3D CFD modeling. Two sources of pollution were considered in the space: CO2 and VOCs. To study resilience, the numerical model was simulated until steady state. Subsequently, a power outage shock of 60 min was induced. The temporal and spatial mappings of temperature, and pollutants’ concentration were recorded in the occupied zone at the breathing height of 1.2 m and compared to that at the exhaust. Building resilience was assessed through ppm.hours and degree.hours and compared at both locations. Results showed that resilience is rather a non-homogeneous field that depends on the location of heat sources and pollution sources in the space. However, results showed that any over or under estimations (~20 − 28%) in assessing the thermal or ventilation resilience are negligible when evaluated at either the breathing plane or the exhaust

Evaluation of thermal resilience to overheating for an educational building in future heatwave scenarios

Airtight and highly insulated buildings are subjected to overheating risks, even in moderate climates, due to unforeseeable events like frequent heatwaves and power outages. Educational buildings share a major portion of building stocks and a large percentage of the energy is expended in maintaining thermal comfort in these buildings. Overheating risks in educational buildings can lead to heat-stress and negatively impact the health conditions and also cognitive performance of the occupants. In the light of increasing severity and longevity of heat waves in future climate scenarios, and associated power outages occurring during the heatwaves, measures to reduce overheating risk while limiting the cooling energy is gaining importance. Since the performance of existing buildings are not guaranteed during events like heatwaves, power outages, it is crucial for these buildings to be resilient to overheating. (Building) resilience is a method to deal with these uncertainties and is stated as 'an ability of the building to withstand disruptions; and to maintain the capacity to adapt, learn and transform'. The focus of this paper is to evaluate thermal resilience for two test lecture equipped with low-energy cooling strategies like natural night ventilation (NNV) and indirect evaporative cooling (IEC) rooms, by dynamic Building Energy Simulations (BES). To assess the thermal resilience to overheating three different heatwaves (HW) files (intense, severe, and longest) for 3 future scenarios (1) Historical (2010-2020), (2) mid-term (2041-2060) and (3) long-term (2081-2100) and a 24h power outage (PO)scenario was simulated. Benchmarking was done with a base case - Typical Meteorological year(TMY) with no power outage. The heatwave files were developed adopting the methodology proposed by the 'Weather Data Task Force' of International Energy Agency Energy in Buildings and Communities Programme (IEA EBC) Annex 80 'Resilient Cooling of Buildings'. This study shows, IEC has high to moderate recovery capacity in TMY period and low recovery capacity in HW period, for a power outage of 24 h. Recovery capacity is low during HW period, especially during an intense and longer HW period when outdoor temperature influences the cooling capacity of the IEC. The results also demonstrates the impact of the thermal mass on the resilience to overheating. Passive survivability assessment indicates, the lecture room with lighter thermal mass does not violate 30 degrees C threshold during a power outage in TMY period and additionally,. recovers faster (11% times faster) from peak temperature compared to lecture room with heavy thermal mass. There is a steep increase in unmet degree hours (occupied hours above24 degrees C threshold) during HW compared to TMY period. This paper gives a directive towards assessment of resilience to overheating and also points out the gap in the existing indicators to assess the resilience

Thermal resilience to overheating assessment in a Belgian educational building with passive cooling strategies during heatwaves and power outages

Airtight and highly insulated educational buildings are subjected to overheating risks, even in moderate climates, due to unforeseeable events like frequent heatwaves (HWs) and power outages (POs) leading to heat-stress and negative impact on the health conditions and cognitive performance of the students. The focus of this paper is to evaluate thermal resilience for two lecture rooms equipped with the low-energy cooling strategies natural night ventilation (NNV) and indirect evaporative cooling (IEC). To assess the thermal resilience to overheating, the lecture rooms were tested with and without passive cooling strategies for 3 Typical meteorological years (TMYs), 3 severe HWs and those 3 HWs + POs. Results evaluating the existing indicators unmet degree hours, indoor overheating degree (IOD), ambient warmness degree (AWD), and overheating escalation factor (αIOD) demonstrated that with passive cooling strategies the two test lecture rooms have good thermal resilience during TMY and HW periods (except long-term severe HW), with 18% higher unmet degree hours during HWs. Lecture room with heavier thermal mass demonstrated higher thermal resilience to overheating in long-term assessment. Furthermore the need to develop a holistic resilience indicator taking into account building and system parameters was also pointed out in this study

Impact of heatwaves and system shocks on a nearly zero energy educational building : is it resilient to overheating?

The characteristic that describes the extent to which buildings and their systems maintain their performance during shocks is called resilience. Building policies in the EU have already addressed the resilience of buildings against possible hazards (i.e., natural disasters, extreme weathers, fires). However, with increasing overheating risks (e.g., climate change) accompanied by their detrimental health and economic impacts, the thermal per-formance of nearly zero energy buildings (nZEB) is not guaranteed. This study aims to assess the impact of shocks and combinations on the thermal resilience of educational nZEB against heatwaves (HW) and system shocks (SS) including failure of indirect evaporative cooling (IEC), natural night ventilation (NNV) and solar shading failure (SF). A Modelica model of the building was developed and experimentally validated. Shocks were classified and quantified using the novel normalized degree of shock (doS) index. Heatwaves (HWs) had 20 x to 93 x more critical impact than the worst SS (NNV failure). Additionally SS occurring at the start of the operational period is 1.2 x more critical than SS occurring later in the day as it allowed for significant heat build-up in both class-rooms. In future climate scenarios a combination of HWs and power outages will become frequent. This study showed that a combination of a full day of cooling strategy and shading failure occurring on the hottest day of a 6-day long HW, is 10% more critical on both lecture rooms than an individual 10-day long HW. Classroom with heavy thermal mass prolongs the absorptivity of the shocks but delays recovery