Summer Thermal Comfort Research Articles

Parametric Modelling and Traditional Architecture: Improving the thermal comfort of the traditional courtyard house in Morocco

The traditional courtyard house of the Mediterranean Basin has been viewed as a complex regulating system that creates a microclimate which historically worked, and still works, in a passive way to provide acceptable thermal comfort in summer. The internal courtyard is generally described as a positive factor that can moderate extreme outdoor climatic conditions. However, some researches have shown that the courtyard could become a negative factor from the energy efficiency point of view. For this purpose, this paper is based on a research study exploring sustainable characteristics of Moroccan traditional housing and its climatic adaptation, delving into the Rabat-Salé case study. A traditional courtyard model is used as a case study to analyze the indoor thermal comfort without using mechanical heating and cooling systems. The thermal behavior of the rooms surrounding the courtyard is analyzed under a temperate and humid climate of Rabat-Salé medina. The simulation modelling is carried out to analyze the effectiveness of different parameters to improve the indoor climate during summer and winter, including the façade orientation, the air infiltration, the surroundings, the ceiling height, the walls and roof/ceiling insulation and the shading devices. Tools for climatic design, Mahoney’s tables, Givoni and Szokolay bio climatic diagrams have been also used to improve design strategies in terms of thermal comfort.

Simulation on the impacts of the street tree pattern on built summer thermal comfort in cold region of China

The phenomenon of global warming and urban heat island has raised the attention for the outdoor thermal comfort. Vegetation in the improvement of urban micro-climate has been confirmed by a large number of scholars. The problem of the uncomfortable summer climate in China's Cold region didn't get enough research. In this paper, the summer thermal comfort of the street canyon has been studied. The main research intent is to analyze the relationship between the street tree pattern and the thermal comfort of street canyon.It’s demonstrated that, in north-south street, it is suitable for the arrangement of street tree to be at the centre on one side of the street. The higher the height of the street tree, the more comfortable thermal environment the street gets. However, when the ratio of the street tree height to the street building is greater than 10:18, the improvement effect decreases. In east-west street, planting the street tree clinging to the street buildings can provide a better thermal comfort improvement effect.The result of this study can serve as a guide to the greening design in China B-cold region and other regions with similar climatic conditions.

Multi-Variable Optimization of Building Thermal Design Using Genetic Algorithms

The building sector is one of the largest energy consumers in the world, comprising about 40% of the total energy consumption in numerous countries. Early design decisions have a significant impact on the energy performance of buildings. The paper presents the multi-variable optimization of the selected design parameters in a single-family building in temperate climate conditions. The influence of four types of windows, their size, building orientation, insulation of external wall, roof and ground floor and infiltration on the life cycle costs (LCC) is analyzed. Optimal selection of the design parameters is carried out using genetic algorithms by coupling the building performance simulation program EnergyPlus with optimization environment. The simulations were conducted for seven optimization cases. The analysis is performed for two variants of a building with heating and cooling systems and with a heating system only. Depending on the analyzed case, the life cycle costs decreased from 7% to 34% LCC value of the reference building. In the case of temperate climate, the building optimization (in terms of heat demand only) substantially reduces the heating costs, yet the summer thermal comfort conditions deteriorate significantly.

Thermal Behavior of a Building Provided With Phase-Change Materials on the Roof and Exposed to Solar Radiation

This paper evaluates the effectiveness of phase change materials (PCMs) for the improvement of summer thermal comfort in lightweight buildings. Experiments have been carried out using PCM in the form of DuPont Energain wallboards in combination with a roof. Two factors influencing the effectiveness of PCM (thickness and location of PCM layer) have been investigated. An experimental study was carried out using two identical test cavities submitted to Casablanca weather. Thermal performance such as the roof surface temperatures and heat flux densities, through the envelope, have been studied. The results indicated that, compared with reference room (without PCM), the thermal storage allows solar radiation to be stored and released up to 6–7 h after solar irradiation; this has effects on both the reduction of daily temperature swings (up to 2 °C) and heat flux (more than 88%). It has been proved that the PCM with a thickness of 10.52 mm on the outer face of the roof has good thermal insulation effect and energy efficiency potential.

B-48 夏期における室内変動気流の温熱的快適性に関する研究 : その2.前後風向の持続時間の影響について

B-48 夏期における室内変動気流の温熱的快適性に関する研究 : その2.前後風向の持続時間の影響について

B-47 夏期における室内変動気流の温熱的快適性に関する研究 : その1 風向変化の影響について

B-47 夏期における室内変動気流の温熱的快適性に関する研究 : その1 風向変化の影響について

An integrated school and schoolyard design method for summer thermal comfort and energy efficiency in Northern China

A good school design consists of a thermally comfortable school and schoolyard as well as a low energy consumption of the school building. The main contribution of this study is that it develops an integrated design approach to systematically evaluate and optimize school design parameters at different design stages for summer outdoor thermal comfort and building cooling demand. A typical school in northern China was selected to illustrate the simulation-based design framework. The three-dimensional microclimate model ENVI-met was used to calculate outdoor temperatures and the Physiological Equivalent Temperature (PET) index as a measure of the outdoor thermal comfort condition. The ENVI-met results were then used as input for the thermal boundary conditions in the energy simulation software DesignBuilder. DesignBuilder, in turn, was applied to calculate the building cooling demand while taking into account the local outdoor thermal conditions. The integrated design approach proves to be effective for mitigating school heat stress and energy saving. By taking the school case as a reference, the integrated design method resulted in a high-performance design that reduced the outdoor discomfort time by 25% and the building cooling demand by 5%. Planting trees was found to be the most effective considering both the outdoor thermal comfort and building cooling demand. Other implications for planning and designing schools in terms of the school case are also presented in order to help architects in selecting strategies that enhance the thermal performance characteristics of both the school building and the schoolyard.

Modelling natural ventilation for summer thermal comfort in Mediterranean dwellings

ABSTRACTNatural ventilation in apartment dwellings in densely built regions could improve occupants' summer thermal comfort and reduce the rapidly increasing energy demand for cooling. This research identified natural ventilation strategies as energy efficient refurbishment solutions for domestic buildings. Four retrofit strategies were tested against the existing single-sided ventilation of an urban multi-storey apartment building in Greece, using computational fluid dynamics simulations. During buoyancy driven flows, acceptable ventilation rates for comfort could be achieved with the implementation of a wind-catcher and a dynamic façade. Under wind-driven ventilation, these strategies delivered significant increases in ventilation rates (up to seven times) and contributed to reductions in indoor air temperatures of up to 2 °C, relative to the existing strategy. Cooling by water evaporation enhanced the cooling performance of the wind-catcher providing up to 4 °C temperature reductions. The successful performance of the proposed strategies highlights their significant potential for reducing energy consumption and improving thermal comfort.

Experimental validation of simulation and measurement-based overheating assessment approaches for residential buildings

ABSTRACTAs a part of the building design process, Estonian building code requires standardized dynamic hourly simulations to verify the building’s compliance to the summer thermal comfort requirements. In this study, we analysed this overheating assessment method for free-running residential buildings, by comparing the simulation results with measured data. Simulation models with different thermal zoning levels were studied: single-zone models, multi-zone apartment models and multi-zone whole building models. We analysed and quantified the effects of modelling detail and thermal zoning on indoor temperature and overheating estimation on the basis of five apartment buildings. Based on the results, a method, using indoor temperature measurements and outdoor climate data, to assess overheating risk has been proposed, as a relatively simple and inexpensive method for pre-defining the need for dynamic simulations.

Refurbishing an Existing Apartment Block in Mediterranean Climate: Towards the Passivhaus Standard

Abstract The Passivhaus standard, although widely appreciated in cold regions, is seldom regarded as a reference in the energy renovation of existing buildings in warm countries. This paper evaluates the effectiveness of a series of strategies for the energy refurbishment of an existing apartment block in Southern Italy, based on dynamic energy simulations. The paper aims to show that, in warm Mediterranean areas, a building refurbishment must not be oriented towards an excessive insulation level. Conversely, if aimed to comply with the Passivhaus standard, the renovation must look above all at those strategies that mitigate the energy needs for space cooling and improve thermal comfort in summer.

Comparison of the Impact of Three Climate Adaptation Strategies on Summer Thermal Comfort – Cases Study in Lyon, France

Nowadays, the study of the outside thermal comfort is more and more taking into consideration in the urban design process. In a climate change context, town planners have to find solutions to mitigate the effects of the global warming and to ensure that outside spaces designed in new districts will remain liveable.In the framework of the EVA project, simulations were carried out to compare the effect of three urban cooling strategies on the thermal comfort in summer. Various urban greenery types, water aspersion systems and cooling materials are applied to three districts in Lyon, France. A set of simulations was designed to explore different configurations:-cooling strategies were first applied one by one in each district,-a composition of the three strategies is considered in a second step to optimize their effect,-cumulative effect is finally investigated by deducing one of the components from the optimized configuration.Simulations were performed using Solene-microclimat which realizes the full coupling between a CFD code and a thermo-radiative model. In this way, Solene-microclimat enables to calculate and evaluate the evolution on the urban microclimate at a district scale considering physical parameters in a completely discretized way. Modules have been introduced in this model to represent different kinds of adaptation strategies such as vegetation (green roofs and walls, trees, lawns) and water aspersion. For each case, the daily variations of surface and air temperatures fields are obtained and compared. The resulting mean radiant temperature is evaluated and investigated for the studied space of each district. Finally, the thermal comfort is assessed using the UTCI index. Findings indicate that vegetation, in particular when including trees is the more efficient, due to its shading effect. Even if water aspersion can strongly lower the surface temperatures, its effect on thermal comfort is local and limited compared to the effect of vegetation. Due to reflection effects, high albedo materials are less efficient concerning external thermal comfort.

Research on Optimization and Biological Characteristics of Harbin Trees Based on Thermal Comfort in Summer

Street trees play a decisive role on creating a comfortable microclimate in summer environment. The paper provides data support for street tree species preferred, by microclimate parameters field measurements of four typical pedestrian street row planting trees, combining with Layman model fit its thermal comfort PET value, comparing human thermal comfort adjustment effect. It was also analyzed to explain the mechanisms regulating trees thermal comfort between the biomorphic characteristics of trees and microclimate parameters by using SPSS statistical analysis software. It was designed to create a comfortable space walk in the urban streets by adjusting the measured effect of thermal comfort through the trees and analysis of thermal comfort adjustment mechanism.

Summer thermal comfort: compliance assessment and overheating prevention in new apartment buildings in Estonia

This study analyses which building parameters contribute the most to overheating in dwellings and which properties will make a room ‘critical’, to be chosen for compliance assessment procedure through temperature simulation, as required in Estonia for new residential buildings. Indoor temperature measurements, conducted in 18 apartments from 16 apartment buildings, show clear evidence of overheating. Compliance assessment of 25 new buildings were conducted using IDA-ICE software. The analysed sample consisted of typical multi-storeyed buildings with mainly massive concrete structures. From the simulated buildings, 68% did not meet the requirements, showing that this relatively new building code requirement was not fully established in practice. Results of the analysis indicate that the requirement in apartment buildings is achievable without cooling, if passive measures are properly applied. Recommendations are given to designers, as well as policy-makers, to improve the situation in the residential building sector.

Assessment of energy and environmental performances of a bioclimatic dwelling in Algeria's North

Bioclimatic architecture strategies and solar active systems contribute strongly to the reduction of building energy demand and achieving thermal comfort for its occupants over the whole year. This paper deals with the study of the energy performance improvement of a pilot bioclimatic house located in Algiers (Algeria). First, a series of experimental measures are conducted during cold period to show the effect of passive and active solar gains on the improvement of the indoor air temperature of the house. Then, a dynamic model of a solar heating system coupled with a bioclimatic house has been developed using TRNSYS software and validated with experimental data. The validated model has been used to establish the energy balance of the pilot bioclimatic house without solar heating system and to compare them to those of a conventional house. Finally, the improvement of the energy balance of the pilot bioclimatic house has been done by passive and active ways. The passive one includes the increase of south facing windows size and the use of night cooling with the use of shading device in summer. The active one consists of the integration of a solar heating system. Furthermore, an environmental study has been performed. The experimental results show that the energy requirements of a pilot bioclimatic house are very low which is suitable for the use of solar heating system in building. The simulation results show that the application of bioclimatic strategies is a better way to provide thermal comfort in summer and decrease the space heating energy demand of the house with 48.70%. The active solar system will cover 67.74% of the energy demand for heating of the house. These energy savings generate a significant reduction in CO2 emissions. Practical application: This work will enable engineers and designers of modern buildings of buildings in a Mediterranean climate to improve building energy efficiency and reduce CO2 emissions by a conjunction of different passive heating and cooling techniques such as insulation, thermal mass, window shades, night ventilation, and the solar heating system. The paper provides designers an effective strategy in terms of energy savings and indoor thermal comfort while reducing CO2 emissions.

Experimental and numerical assessment of cool-roof impact on thermal and energy performance of a school building in Greece

This paper presents an investigation of cool-roof impacts on thermal and energy performance of a School building located in Athens, Greece. The research work refers to a month recording of thermal performance indicators (TPIs) in selected classrooms, namely indoor air- roof- and ceiling surface- temperature. Thermal inspections also included roof thermal-camera scanning and reflectance measurements of exterior building surfaces. Thermal impacts were assessed in terms of comparisons of TPIs with the ones obtained by the same procedure in a nearby twin building. The impact of the cool roof on building energy performance and thermal comfort was assessed through dynamic energy simulations. Model calibration is achieved through comparisons of simulated indoor air temperature with the measured one in both the ex-ante and ex-post condition. Two summer-conditioning cases were analyzed, namely “ceiling fans with no cooling systems” (actual condition) and “air-conditioning split units with no ventilation systems”. For the building block below the cool roof it was found that: in the former case, the energy consumption for ventilation is reduced by at least 25% with an up to 3% increase of comfort operating hours, at the expense of a 12% heating penalty in winter. In the latter case, the energy consumption for cooling is reduced by at least 18% with a similar increase of comfort hours, compensating energy-consumption increase for heating in winter. It is concluded that the cool roof is an efficient solution for School buildings in warm climates as it improves summer thermal comfort and ensures annual energy savings when heat pumps are used for cooling purposes.

Comparative thermal study between conventional and bioclimatic office buildings

The presented research focuses on the comparison of energy performance of a conventional versus a bioclimatic building, both continuously monitored. Attached buildings of offices located in Madrid, with main orientation N-S, have been built considering different constructive criteria. Principal Components Analysis has been used to check the representativeness criteria of the analysed offices. The Box and Whisker method concluded that the bioclimatic building has registered lower inter-quartile ranges for indoor temperatures than the convectional building. Thermal oscillations have been calculated for both buildings during winter and summer campaigns. The behaviour of the bioclimatic building is close to the summer thermal comfort band however during winter period values are slightly above because upper temperature limit has been exceeded. Thermal assessment of monitored offices has been done for representative days of summer and winter periods. The temperature variation of bioclimatic offices is more stable compared to conventional ones. Global primary energy consumption has been reduced from 124.58 kWh/m2 year in conventional building up to 80.84 kWh/m2 year in bioclimatic building.

Microclimate design for open spaces: Ranking urban design effects on pedestrian thermal comfort in summer

The paper presents a study on the influence of urban morphology and urban design parameters such as street and building geometry, landscape elements including vegetation types, water surfaces and material properties and their effects on pedestrian thermal comfort in cities. The data provided by the paper are based on simulations using selected computational tools (ENVI-met, RadTherm and Fluent) and performed for two typical urban spaces, a square and a courtyard. The paper focuses on summer conditions which include increasingly uncomfortable periods. It draws upon studies initiated in the city of Thessaloniki in northern Greece. However, the findings apply to many other cities with similar morphological characteristics and summer design conditions. The results are ranked according to the influence each of the design parameters considered can have on pedestrian thermal comfort. Spatial and temporal variations are highlighted. Special mention is given to the high impact of trees and soil humidity and the contrasting effects of pavement albedo. The paper provides data for use by urban designers in specifying appropriate microclimatic interventions to improve pedestrian comfort.

Influence of Urban Morphology on Outdoor Thermal Comfort in Summer: A Study in Tunis, Tunisia

Influence of Urban Morphology on Outdoor Thermal Comfort in Summer: A Study in Tunis, Tunisia

Analysis of the predicted effect of passive climate adaptation measures on energy demand for cooling and heating in a residential building

Both new and existing buildings need to be adapted to climate change, in order to keep providing a comfortable and healthy indoor climate. Preferably, the adaptation measures applied at the building level scale do not require additional energy (i.e. passive measures). Previous studies showed that passive climate change adaptation measures can have a positive effect on thermal comfort in summer and its shoulder seasons in non-air-conditioned residential buildings. In this paper, the effect of these passive climate adaptation measures – applied at building component level – on the cooling and heating energy demand of a terraced house is analyzed using building energy simulations. It is shown that for this particular case the required cooling energy can be limited to a large extent (59–74%) when external solar shading or additional natural ventilation is applied. In addition, it is shown that for a well-insulated terraced house the energy cost for heating is not strongly affected by the application of passive climate change adaptation measures.

Comparison of the Efficiency of Building Hybrid Ventilation Systems with Different Thermal Comfort Models

Building hybrid ventilation integrates the advantages of both natural ventilation and mechanic ventilation. Ventilation efficiencies and system costs are found to be associated with different control strategies. Two indoor thermal comfort indices, which are predicted mean vote (PMV) model and adaptive comfort standard (ACS) model, are chosen as the control objective in this paper. A hybrid ventilation system with these thermal models was developed. Experimental tests were conducted to compare the time percentage of thermal comfort in summer, and the running time of the exhaust fan between the two systems. The results show that the percentage of the interior thermal comfort time is between 64.5% and 86.4% when the outside air temperature is between 10°C and 25°C (the average temperature is about 17.5°C, Period 1). The percentage is 45.2∼60.7% when the outside air temperature was 13∼32°C (the average temperature is about 22.7°C, Period 2), and 29.4∼49.3% when the outside air temperature was 18∼34°C (the average temperature is about 26.5°C, Period 3). The comfort time percentage is always higher with ACS model than that with PMV model in these three test periods. The results also indicate that the ventilation efficiency, which is defined as ratio of window opening time to the fan's running time, is higher with the ACS model than that with the PMV model in the period 2 and 3. The ACS model could be considered as the prior control objective for the hybrid ventilation system.