scholarly journals Thermal mass and thermal comfort in offices – experimental studies of a concrete floor

2019 ◽  
Vol 282 ◽  
pp. 02087 ◽  
Author(s):  
Steinar Grynning ◽  
Alessandro Nocente ◽  
Lars Gullbrekken ◽  
Kjell Skjeggerud
Keyword(s):  
Thermal Comfort ◽  
Energy Demand ◽  
Natural Ventilation ◽  
Experimental Studies ◽  
Mass Effect ◽  
Thermal Capacity ◽  
Thermal Mass ◽  
Peak Reduction ◽  
Single Person ◽  
Wood Flooring

Previous studies demonstrated that the use of thermal mass in buildings can contribute to reduce the energy demand and improve the thermal comfort. The thermal mass effect strongly depends on the properties of the materials facing the internal environment. High thermal capacity and conductivity are vital to achieve the desired effects. Concrete have both and it is a common building material. However, scientifically sound experimental studies that quantify the effects in a controlled environment are scarce. The aim is to study the effects of thermal mass on indoor environment and comfort in a quantifiable way in an extensive experimental campaign where comparative measurements were carried out in The ZEB TestCell Laboratory in Trondheim, Norway. The facility consists of two identical real-weather exposed rooms the size of a single person office. One of the rooms was constructed with a 70 mm thick concrete flooring, the other with an 18 mm wood-flooring. Free-floating temperature propagations were measured in different natural ventilation scenarios. The results showed that peak temperatures were notably reduced in the test room with the concrete flooring. During the warmest periods, a temperature peak reduction of more than 10% was found compared to the wooden-floored room.

scholarly journals Experimental Data and Simulations of Performance and Thermal Comfort in a Typical Mediterranean House

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3311
Author(s):  
Víctor Pérez-Andreu ◽  
Carolina Aparicio-Fernández ◽  
José-Luis Vivancos ◽  
Javier Cárcel-Carrasco
Keyword(s):  
Energy Efficiency ◽  
Thermal Comfort ◽  
Energy Demand ◽  
Natural Ventilation ◽  
Thermal Characterization ◽  
Energy Performance ◽  
Building Stock ◽  
Energy Demands ◽  
Dwelling House ◽  
Account Standard

The number of buildings renovated following the introduction of European energy-efficiency policy represents a small number of buildings in Spain. So, the main Spanish building stock needs an urgent energy renovation. Using passive strategies is essential, and thermal characterization and predictive tests of the energy-efficiency improvements achieving acceptable levels of comfort for their users are urgently necessary. This study analyzes the energy performance and thermal comfort of the users in a typical Mediterranean dwelling house. A transient simulation has been used to acquire the scope of Spanish standards for its energy rehabilitation, taking into account standard comfort conditions. The work is based on thermal monitoring of the building and a numerical validated model developed in TRNSYS. Energy demands for different models have been calculated considering different passive constructive measures combined with real wind site conditions and the behavior of users related to natural ventilation. This methodology has given us the necessary information to decide the best solution in relation to energy demand and facility of implementation. The thermal comfort for different models is not directly related to energy demand and has allowed checking when and where the measures need to be done.

CFD simulations for examining natural ventilation in the learning spaces of an educational building with courtyards in Madurai

2019 ◽  
Vol 41 (4) ◽  
pp. 466-479
Author(s):  
S Subhashini ◽  
K Thirumaran
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Thermal Comfort ◽  
Natural Ventilation ◽  
Numerical Study ◽  
Educational Institution ◽  
Experimental Studies ◽  
Building Design ◽  
Learning Spaces ◽  
Naturally Ventilated Buildings

This paper attempts to investigate the potential of courtyards in optimizing natural ventilation and improving comfort levels in the learning spaces of a naturally ventilated educational institution with courtyards in the warm-humid climatic region of Madurai. Field measurements and experimental studies were carried out to predict the indoor and outdoor environmental conditions. The numerical study was carried out using computational fluid dynamics-based simulations using Ansys Fluent as the solver. The main aim of the simulation is to understand the airflow pattern and air velocity fields inside the classrooms surrounding the courtyards for different wind directions. The computational fluid dynamics results were validated by comparing it with the experimental results obtained in the current study and numerical results from other studies. The major findings of the current study suggest that courtyards with an aspect ratio of 1:2, orientations of openings at an angle of 0–20° to the predominant wind directions and the overall percentage of openings between 15 and 30% in buildings in Madurai region can enhance natural ventilation and thus improve thermal comfort of the occupants. Practical application: Naturally ventilated buildings in warm-humid climates have difficulty in providing thermal comfort to the occupants. CFD tools have been used to predict the ventilation performance of a naturally ventilated educational building with courtyards. The CFD results were helpful in identifying the implication of building design on the indoor air flow pattern. The recommendations given in this paper are applicable to any building type which relies on natural ventilation for thermal comfort provided they have similar building configurations, boundary conditions and weather conditions. The study is intended to help architects and building designers in the effective design of naturally ventilated buildings with respect to its climatic conditions.

The Application of Computer Simulations on one Commercial Building to Improve Energy Performance

2010 ◽  
Vol 171-172 ◽  
pp. 364-367
Author(s):  
Jia Fang Song
Keyword(s):  
Thermal Comfort ◽  
Energy Demand ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Energy Performance ◽  
Comfort Level ◽  
Commercial Building ◽  
Simulation Tools ◽  
Output Performance ◽  
Support Software

This paper introduces the application of the TAS simulation support software to determine the energy performance in between a full mechanical ventilated building than that of a hybrid ventilated-- combined mechanical and naturally ventilated (atrium area to be naturally ventilated) building. A modeled three-storey commercial office building will be used as the main subject of this analysis. To determine the thermal comfort level of the central atrium, Parameters will be set in such a way that the full height windows will be 100% open. Results will be then tabularized to determine and analysis the output of the simulation. Recommendations will be then given based on the output performance of the building. In Tropics, it’s very difficult to achieve better thermal comfort in a naturally ventilated building. With the help of these simulation tools we can find whether natural ventilation is possible in this tropical climate in terms of thermal comfort, ventilation system and energy demand.

scholarly journals Evaluation of the Thermal Comfort and Energy Demand in a Building with Rammed Earth Walls in Spain: Influence of the Use of In Situ Measured Thermal Conductivity and Estimated Values

Buildings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 635
Author(s):  
Miguel Ángel Mellado Mascaraque ◽  
Francisco Javier Castilla Pascual ◽  
Víctor Pérez Andreu ◽  
Guillermo Adrián Gosalbo Guenot
Keyword(s):  
Thermal Conductivity ◽  
Thermal Comfort ◽  
Energy Demand ◽  
Winter Period ◽  
Rammed Earth ◽  
Thermal Mass ◽  
Nominal Data ◽  
K Value ◽  
Earth Walls

This paper describes the influence of thermal parameters—conductivity, transmittance, and thermal mass—in the estimation of comfort and energy demand of a building with rammed earth walls, and consequently, the compliance with standards. It is known that nominal design data does not match in situ measured values, especially in traditionally constructed buildings. We have therefore monitored a room in a building with rammed earth walls, designed a computerised model, and compared four different alternatives where we have changed the value for the thermal conductivity (in situ vs. estimated) and the consideration of thermal mass. When we then analyse the compliance with the Spanish energy saving code, using measured values would result in lower differences with the standards’ limits and even comply with the global thermal transmittance (K-value) requirement. This would mean a more realistic approach to the restoration of traditional buildings leading to the use of thinner and more suitable insulation and retrofitting systems, encouraging the use of rammed earth in new buildings, and therefore reducing the carbon footprint due to materials used in construction. Results show that the building model that uses in situ values and considers thermal mass (S1) is closer to reality when assessing thermal comfort. Finally, using nominal data would result in requiring 43% more energy in the selected winter period and 102% more energy in the selected summer period to keep the same comfort conditions as in the alternative where measured values are used.

scholarly journals Keeping Cool in the Desert: Using Wind Catchers for Improved Thermal Comfort and Indoor Air Quality at Half the Energy

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 100
Author(s):  
Jamal Saif ◽  
Andrew Wright ◽  
Sanober Khattak ◽  
Kasem Elfadli
Keyword(s):  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Energy Demand ◽  
Air Conditioning ◽  
Natural Ventilation ◽  
Energy Use ◽  
Cooling System ◽  
Evaporative Cooling

In hot arid climates, air conditioning in the summer dominates energy use in buildings. In Kuwait, energy demand in buildings is dominated by cooling, which also determines the national peak electricity demand. Schools contribute significantly to cooling demand, but also suffer from poor ventilation. This paper presents analysis of a ventilation and cooling system for school classrooms using a wind catcher for natural ventilation and evaporative cooling. A school classroom in Kuwait with single-sided ventilation was modelled using the DesignBuilder V5.4/EnergyPlus V9.1 software and calibrated using field data. The model was used to analyse the performance of a wind catcher, with and without evaporative cooling, in terms of energy use, thermal comfort and indoor air quality. Compared to the baseline of using air-conditioning only, a wind catcher with evaporative cooling was found to reduce energy use by 52% during the summer months while increasing the comfortable hours from 76% to 100% without any supplementary air conditioning. While the time below the ASHRAE CO2 limit also improved from 11% to 24% with the wind catcher, the indoor air quality was still poor. These improvements came at the cost of a 14% increase in relative humidity. As the wind catcher solution appears to have potential with further development; several avenues for further research are proposed.

URBAN FACADE GEOMETRY ON OUTDOOR COMFORT CONDITIONS: A REVIEW

2020 ◽  
Vol 4 (1) ◽  
pp. 45
Author(s):  
Elahe Mirabi ◽  
Nasrollahi Nazanin
Keyword(s):  
Thermal Comfort ◽  
Urban Areas ◽  
Natural Ventilation ◽  
Flow Behavior ◽  
Air Flow ◽  
Urban Geometry ◽  
Wide Range ◽  
Low Energy Buildings ◽  
Outdoor Comfort ◽  
Solar Access

<p>Designing urban facades is considered as a major factor influencing issues<br />such as natural ventilation of buildings and urban areas, radiations in the<br />urban canyon for designing low-energy buildings, cooling demand for<br />buildings in urban area, and thermal comfort in urban streets. However, so<br />far, most studies on urban topics have been focused on flat facades<br />without details of urban layouts. Hence, the effect of urban facades with<br />details such as the balcony and corbelling on thermal comfort conditions<br />and air flow behavior are discussed in this literature review. <strong>Aim</strong>: This<br />study was carried out to investigate the effective factors of urban facades,<br />including the effects of building configuration, geometry and urban<br />canyon’s orientation. <strong>Methodology and Results</strong>: According to the results,<br />the air flow behavior is affected by a wide range of factors such as wind<br />conditions, urban geometry and wind direction. Urban façade geometry<br />can change outdoor air flow pattern, thermal comfort and solar access.<br /><strong>Conclusion, significance and impact study</strong>: In particular, the geometry of<br />the facade, such as indentation and protrusion, has a significant effect on<br />the air flow and thermal behavior in urban facades and can enhance<br />outdoor comfort conditions. Also, Alternation in façade geometry can<br />affect pedestrians' comfort and buildings energy demands.</p>

scholarly journals Heating and Cooling Degree-Days Climate Change Projections for Portugal

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 715
Author(s):  
Cristina Andrade ◽  
Sandra Mourato ◽  
João Ramos
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Thermal Comfort ◽  
Energy Demand ◽  
Residential Buildings ◽  
Degree Days ◽  
Climate Change Projections ◽  
Heating And Cooling ◽  
Cooling Degree Days ◽  
Heating Energy Demand

Climate change is expected to influence cooling and heating energy demand of residential buildings and affect overall thermal comfort. Towards this end, the heating (HDD) and cooling (CDD) degree-days along with HDD + CDD were computed from an ensemble of seven high-resolution bias-corrected simulations attained from EURO-CORDEX under two Representative Concentration Pathways (RCP4.5 and RCP8.5). These three indicators were analyzed for 1971–2000 (from E-OBS) and 2011–2040, and 2041–2070, under both RCPs. Results predict a decrease in HDDs most significant under RCP8.5. Conversely, it is projected an increase of CDD values for both scenarios. The decrease in HDDs is projected to be higher than the increase in CDDs hinting to an increase in the energy demand to cool internal environments in Portugal. Statistically significant linear CDD trends were only found for 2041–2070 under RCP4.5. Towards 2070, higher(lower) CDD (HDD and HDD + CDD) anomaly amplitudes are depicted, mainly under RCP8.5. Within the five NUTS II

scholarly journals Window operation behaviour and indoor air quality during lockdown: A monitoring-based simulation-assisted study in London

2021 ◽  
pp. 014362442110177
Author(s):  
Farhang Tahmasebi ◽  
Yan Wang ◽  
Elizabeth Cooper ◽  
Daniel Godoy Shimizu ◽  
Samuel Stamp ◽  
...  
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Energy Demand ◽  
Natural Ventilation ◽  
Probabilistic Models ◽  
Performance Model ◽  
Outdoor Environment ◽  
Ventilation Strategies ◽  
The Impact

The Covid-19 outbreak has resulted in new patterns of home occupancy, the implications of which for indoor air quality (IAQ) and energy use are not well-known. In this context, the present study investigates 8 flats in London to uncover if during a lockdown, (a) IAQ in the monitored flats deteriorated, (b) the patterns of window operation by occupants changed, and (c) more effective ventilation patterns could enhance IAQ without significant increases in heating energy demand. To this end, one-year’s worth of monitored data on indoor and outdoor environment along with occupant use of windows has been used to analyse the impact of lockdown on IAQ and infer probabilistic models of window operation behaviour. Moreover, using on-site CO2 data, monitored occupancy and operation of windows, the team has calibrated a thermal performance model of one of the flats to investigate the implications of alternative ventilation strategies. The results suggest that despite the extended occupancy during lockdown, occupants relied less on natural ventilation, which led to an increase of median CO2 concentration by up to 300 ppm. However, simple natural ventilation patterns or use of mechanical ventilation with heat recovery proves to be very effective to maintain acceptable IAQ. Practical application: This study provides evidence on the deterioration of indoor air quality resulting from homeworking during imposed lockdowns. It also tests and recommends specific ventilation strategies to maintain acceptable indoor air quality at home despite the extended occupancy hours.

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